Pancreatic cancer

Pancreatic cancer
Specialty	Oncology, gastroenterology

Pancreatic cancer is a disease caused by cells in the pancreas - a glandular organ located behind the stomach - multiplying out of control. Signs and symptoms of pancreatic cancer may include abdominal or back pain, yellow skin, unexplained weight loss, light colored stools, dark urine and loss of appetite. However, there are usually no symptoms in the disease's early stages. Symptoms that are specific enough to suspect pancreatic cancer often do not appear until the disease is already in an advanced stage. By the time of diagnosis the cancer has usually spread to other parts of the body.

Pancreatic cancer is rare in those younger than 40, and more than half of cases occur in people over the age of 71. The disease is more common among people who smoke, are obese, have diabetes, or who have certain rare genetic conditions including: multiple endocrine neoplasia type 1 and hereditary nonpolyposis colon cancer among others. A smoker's chances of developing the disease are reduced if they cease smoking, after which the risk of the disease returns to normal within 20 years. Other recommendations include limiting alcohol intake and eating a healthy diet. About a quarter (25%) of cases are linked to tobacco smoking, while a minority (5-10%) of cases are linked to inherited genes. Screening the general population has not been found to be effective.

There are a number of different types of pancreatic cancer, but pancreatic adenocarcinoma accounts for more than 8 out of 10 (85%) cases , and references to pancreatic cancer often refer only to that type. Adenocarcinomas start within the part of the pancreas that makes digestive enzymes, known as the exocrine pancreas. One to 2 in every hundred cases are neuroendocrine tumors, and arise from the hormone-producing islet cells in the pancreas. There are also a number of other types of pancreatic cancer.

Pancreatic cancer is usually diagnosed by a combination of medical imaging (such as ultrasound and computed tomography), blood tests (such as CEA and CA 19-9) and examination of tissue samples (biopsy). This allows the disease to be divided into stages, from early (stage I) to late (stage IV).

The disease can be treated with surgery, radiotherapy, chemotherapy, or a combination of these. Recommendations are partly based on the cancer stage. Surgery is the only treatment that can cure the disease, but may also be done to try to improve quality of life without trying to cure. Pain management and medications to improve digestion are sometimes needed. Early palliative care is recommended even in those who are receiving treatment aimed at curing it.

In 2012 pancreatic cancers of all types caused 330,000 deaths globally, the 7th most common cause of deaths due to cancer. In the United States it is the 4th most common cause of deaths due to cancer. The disease occurs more often in the developed world, which had more than two-thirds (68%) of new cases in 2012. Pancreatic adenocarcinoma typically has poor outcomes, with 25 out of every 100 patients alive one year after diagnosis, and just 5 out of every 100 alive after 5 years. In localized disease where the cancer is small (< 2 cm) at diagnosis, the number alive after 5 years is approximately 20%. Neuroendocrine cancers have better outcomes - two-thirds (65%) of people are still alive after 5 years, although this varies considerably depending on the type of neuroendocrine tumour. In the United States, as of 2006, the economic costs of pancreatic cancer are estimated at $8.6 billion.

Classification

The many different cancers that can affect the pancreas can be divided into two groups. First is the 99% of cases that occur in the exocrine (or "non-endocrine") parts of the pancreas. There are several types of these, but their diagnosis and treatment have much in common. The remaining 1% of pancreatic cancers are in the endocrine parts of the pancreas, and often have different symptoms and treatment to the exocrine types, although surgery offers the only possibility of curing both groups. Both groups mainly (but not exclusively) occur in people over 40, and are slightly more common in men, but some rare sub-types mainly occur in women or children. For all types the only curative treatment is surgery, and for most sub-types the outcomes are typically poor.

Exocrine

The exocrine group is dominated by pancreatic adenocarcinoma ("invasive" and "ductal" may be added to this term), which is by far the most common type, representing about 85% of all pancreatic cancers, although the pancreatic ductal epithelium from which it arises represents less than 10% of the pancreas by cell volume. This arises in the tiny ducts that carry the pancreatic exocrine products away, and is covered in detail in other sections. The next most common, acinar cell carcinoma of the pancreas arises in the cells that make these products, and represents 5% of exocrine pancreas cancers. Like "functioning" endocrine cancers, it may cause over-production of pancreatic products, in this case digestive enzymes, which may produce symptoms including skin rashes and joint pain. Cystadenocarcinoma represents 1% and has a better prognosis than other types. Pancreatoblastoma is a rare form, mostly occurring in childhood, and with a relatively good prognosis. Other exocrine cancers include adenosquamous carcinomas, signet ring cell carcinomas, hepatoid carcinomas, colloid carcinomas, undifferentiated carcinomas, and undifferentiated carcinomas with osteoclast-like giant cells. Solid pseudopapillary tumour is a rare low-grade neoplasm that mainly affects younger women, and has a very good prognosis.

Pancreatic mucinous cystic neoplasms are a broad group of pancreas tumors that have varying malignant potential. They are being detected at a greatly increased rate as CT scans become more powerful and common, and discussion continues as how best to assess and treat them, as many are benign.

Endocrine

There are a number of types, all of which can be considered rare. They form part of a wider classification of neuroendocrine tumors ("NETs"), with which they have much in common, and those forming in the pancreas are referred to as "PanNETs" for convenience. They are divided into "functioning" and "non-functioning" types. The functioning types produce endocrine hormones such as insulin, gastrin, and glucagon, often in large quantities that give rise to serious symptoms such as low blood sugar, which makes them likely to be detected relatively early. The most common of the group are insulinomas and gastrinomas, named after the hormones they secrete. The non-functioning types produce no hormones, and typically no symptoms at an early stage. They are often only diagnosed after the cancer has spread to other parts of the body. The non-functioning types are estimated in recent clinical guidelines to form either up to 90% of PanNETs, or alternatively 45-60%.

In the Medical Subject Headings classification, PanNETs are divided between Islet cell carcinomas (C04.588.322.475.500, sub-heads Gastrinoma, Glucagonoma, Somatostatinoma and Vipoma), and Islet cell adenomas, sub-head insulinoma, but there are a number of still rarer types. All PanNets used to be referred to by terms such as "islet cell cancer", referring to the islets of Langerhans in the pancreas, but it has become clear that they do not arise in islet cells, as previously thought.

Signs and symptoms

The pancreas and some surrounding structures (duodenum, aorta, spleen, bile duct) showing important structural features, as well as some physiological functions. (Histology of pancreatic islet in zoom window.)

The pancreas produces a number of enzymes involved in digestion, as well as several hormones (from pancreatic islets) involved in regulation of digestion and metabolism. Pancreatic cancer may lead to loss of any of these functions.

Early pancreatic cancer usually does not cause symptoms, so that the disease is typically not diagnosed until it has spread beyond the pancreas itself. This is one of the key factors in the poor survival rate. Exceptions to this are the functioning PanNETs, whose over-production of hormones is likely to give a range of symptoms according to the type, although these may not always be correctly identified initially.

Common symptoms of pancreatic adenocarcinoma occurring before diagnosis, bearing in mind that the disease is rarely diagnosed before the age of 40, include:

• Pain in the upper abdomen or back, often spreading from around the stomach to the back. The location of the pain can indicate the part of the pancreas where a tumor is located. The pain may be worst at night and may increase over time to become "severe and unremitting". It may be slightly relieved by bending forwards. In the UK, about half of new cases of pancreatic cancer are diagnosed following a visit to a hospital emergency department for pain or jaundice, or both. Up to 2/3 of patients have abdominal pain, 46% accompanied by jaundice, with 13% having jaundice without pain.
• Painless jaundice (yellow tint to whites of eyes (sclera) or yellowish skin, possibly in combination with darkened urine) when a cancer of the head of the pancreas (75% of cases) obstructs the common bile duct as it runs through the pancreas. This may also cause pale-colored stool and steatorrhea. The jaundice may be associated with itching as the salt from excess bile can cause skin irritation.
• Unexplained weight loss (cachexia), either from loss of appetite, or loss of exocrine function resulting in poor digestion. The tumor may compress neighbouring organs, disrupting digestive processes routes such as making it difficult for the stomach to empty, which may cause nausea and a feeling of fullness. This often results in fatty stools or steatorrhea as the undigested fat completes its journey: "Patients describe foul smelling, oily stools that are difficult to flush away".
• At least 50% of cases of pancreatic adenocarcinoma have diabetes at the time of diagnosis. Diabetes may be a risk factor as well as a symptom. People over 50 who develop diabetes have eight times the risk of developing pancreatic adenocarcinoma within three years, after which the relative risk declines, suggesting new onset diabetes in an elderly individual may be an early warning sign of pancreatic cancer.

Other symptoms

• Indigestion (dyspepsia) or heartburn.
• Trousseau's syndrome, in which blood clots form spontaneously in the portal blood vessels, the deep veins of the extremities, or the superficial veins anywhere on the body, may be associated with pancreatic cancer, and is found in about 10% of cases.
• Pulmonary embolisms due to pancreatic cancers producing blood clotting chemicals.
• Clinical depression has been reported in association with pancreatic cancer in some 10-20% of cases, and can be a hindrance to optimal management. The depression may be there before the cancer is diagnosed, and is perhaps caused by the cancer. But the mechanism for this association is not known.
• Symptoms of pancreatic cancer metastasis. Typically, pancreatic cancer first metastasizes to regional lymph nodes, and later to the liver or to the peritoneal cavity, large intestine or lungs; it rarely metastasizes to bone or brain.

Risk factors

Risk factors for pancreatic cancer include:

• Age, gender and race. The risk of developing pancreatic cancer increases with age. Most cases occur after age 65, while cases before age 40 are uncommon. The disease is somewhat more common in men than women, and in the United States is over 1.5 times more common in African Americans, though incidence in Africa is low.
• Cigarette smoking is the best established avoidable risk factor for pancreatic cancer, approximately doubling risk among long-term smokers, with the risk increasing with the number of cigarettes smoked and the years of smoking. The risk declines slowly after smoking cessation, taking some 20 years to return to that of non-smokers.
• Obesity; a BMI greater than 35 is associated with a risk ratio of 1.55.
• Family history: 5–10% of pancreatic cancer cases have an inherited component, with many patients having a family history of pancreatic cancer. Most of the genes involved have not been identified. Hereditary pancreatitis gives a greatly increased lifetime risk of pancreatic cancer, of 30–40% to the age of 70. Screening for early pancreatic cancer may be offered to individuals with hereditary pancreatitis on a research basis. Some patients may choose to have their pancreas surgically removed to prevent cancer developing in the future.

Pancreatic cancer has been associated with the following hereditary syndromes: autosomal recessive ataxia-telangiectasia and autosomal dominantly inherited mutations in the BRCA2 gene and PALB2 gene, Peutz-Jeghers syndrome due to mutations in the STK11 tumor suppressor gene, hereditary non-polyposis colon cancer (Lynch syndrome), familial adenomatous polyposis, and the familial atypical multiple mole melanoma-pancreatic cancer syndrome (FAMMM-PC) due to mutations in the CDKN2A tumor suppressor gene.

• Chronic pancreatitis increases risk by a factor of 2.71, and as with diabetes, new-onset pancreatitis may be a symptom of a tumor. The risk of pancreatic cancer in individuals with familial pancreatitis is particularly high.
• Diabetes mellitus is both a risk factor for pancreatic cancer, and, as noted earlier, new onset diabetes can be an early sign of the disease. People who have been diagnosed with Type 2 diabetes for longer than 10 years have a 1.51 risk factor compared to non-diabetics.
• Gingivitis or periodontal disease
• Diet is not generally accepted as a direct risk factor (though see the sections on obesity and alcohol). Some studies have found links with diets high in red meat, processed meat, and sugar-sweetened drinks (soft drinks).
• Partial gastrectomy

Alcohol

While the association between alcohol abuse and pancreatitis is well established, considerable research has failed to firmly establish alcohol consumption as a risk factor for pancreatic cancer. Overall, the association is consistently weak and the majority of studies have found no association. Although drinking alcohol excessively is a major cause of chronic pancreatitis, which in turn predisposes to pancreatic cancer, chronic pancreatitis associated with alcohol consumption is less frequently a precursor for pancreatic cancer than other types of chronic pancreatitis.

Diagnosis

The head, body and tail of the pancreas

Axial CT image with i.v. contrast. Macrocystic adenocarcinoma of the pancreatic head.

Pancreatic adenocarcinoma has a number of symptoms, but none that are individually distinctive to it, or appear in the early stages of disease. Pain is present in 80% to 85% of patients with locally advanced or advanced metastatic disease. The pain is usually felt in the upper abdomen as a dull ache that radiates straight through to the back. It may be intermittent and made worse by eating. Weight loss can be profound; it can be associated with anorexia, early satiety, diarrhoea, or steatorrhea. Jaundice is often accompanied by pruritus and dark urine. Painful jaundice is present in approximately one-half of patients with locally unresectable disease, while painless jaundice is present in approximately one-half of patients with a potentially resectable and curable lesion.

The symptoms presented at diagnosis vary according to the location of the cancer on the pancreas, which anatomists divide (going from left to right on most diagrams) into the thick head, the neck, and the tapering body, ending in the tail. About 60-70% of adenocarcinomas are in the head, and 20-25% in the body or tail. Malignancies in the pancreatic body or tail usually present with pain and weight loss, while those in the head of the gland typically present with steatorrhea, weight loss, and jaundice.

The recent onset of atypical diabetes mellitus, a history of recent but unexplained thrombophlebitis (Trousseau sign), or a previous attack of pancreatitis are sometimes noted. Courvoisier's sign is the presence of jaundice with a painlessly swollen gallbladder and is strongly indicative of pancreatic cancer. It can be used to distinguish pancreatic cancer from gallstones. Tiredness, irritability and difficulty eating because of pain may be present. Medical Imaging techniques, such as computed tomography (CT scan) and endoscopic ultrasound (EUS) are used both to confirm the diagnosis and help the decision as to whether surgery can be used (resectability). Magnetic resonance imaging and positron emission tomography may also be used. Abdominal ultrasound is less sensitive and will miss small tumors, but can identify metastisis to the liver and the build-up of fluid in the peritoneal cavity (ascites). It may be used for a quick and cheap first examination before other techniques.

A biopsy by fine needle aspiration, often guided by endoscopic ultrasound, may be used where there is uncertainty over the diagnosis, but a histologic diagnosis is not usually required for removal of the tumor by surgery to go ahead. However analysis of the tissue removed by surgery helps determine which chemotherapy regimen to start. Pancreatic cancer is usually staged using a CT scan.

Liver function tests can show a combination of results indicative of bile duct obstruction (raised conjugated bilirubin, γ-glutamyl transpeptidase and alkaline phosphatase levels). CA19-9 (carbohydrate antigen 19.9) is a tumor marker that is frequently elevated in pancreatic cancer. However, it lacks sensitivity and specificity, not least because 5% of people lack the Lewis (a) antigen and cannot produce CA19-9. It has a sensitivity of 80% and specificity of 73% in for detecting pancreatic adenocarcinoma, and is used for following known cases rather than diagnosis.

The most common form of pancreatic cancer (ductal adenocarcinoma) is typically characterized by moderately to poorly differentiated glandular structures on microscopic examination. There is typically considerable formation of fibrous tissue (desmoplasia) around the tumour. This creates an environment that is short of blood vessels (hypovascular) and so of oxygen (Tumor hypoxia). It is thought that this prevents many chemotherapy drugs from reaching the tumor, as one factor making the cancer especially hard to treat. Pancreatic cancer has an immunohistochemical profile that is similar to hepatobiliary cancers (e.g. cholangiocarcinoma) and some stomach cancers; thus, it may not always be possible to be certain that a tumour found in the pancreas arose from it.

Staging

The cancer staging system used internationally for pancreatic cancer is that of the American Joint Committee on Cancer and Union for International Cancer Control, so AJCC-UICC, which makes an important distinction within Stage II, between tumors that are classed as "borderline resectable" because they do not involve the celiac axis or superior mesenteric artery, and "unresectable". Surgery is likely to be possible for the former, but is not for the latter. These are T3 and T4 respectively in the associated TNM staging system, which builds up an overall stage by assessing the Tumor size, spread to lymph Nodes and Metastasis. A simpler practical classification groups cases as "resectable", "borderline resectable", and "unresectable" because locally advanced or metastatic.

• 
  Stage T1 pancreatic cancer
• 
  Stage T2 pancreatic cancer
• 
  Stage T3 pancreatic cancer
• 
  Stage T4 pancreatic cancer
• 
  Pancreatic cancer in nearby lymph nodes - Stage N1
• 
  Pancreatic cancer metastasized - stage M1

Locally advanced adenocarcinomas have spread into neighboring organs, which may be any of the following (in roughly decreasing order of frequency): the duodenum, stomach, transverse colon, spleen, adrenal gland, or kidney. Very often they also spread to the important blood or lymphatic vessels and nerves that run close to the pancreas, making surgery far more difficult. Typical sites for metastasic spread are the liver, peritoneal cavity and lungs, all of which occur in 50% or more of fully advanced cases.

Mechanism

Micrograph of pancreatic ductal adenocarcinoma (the most common type of pancreatic cancer). H&E stain.

Exocrine pancreas cancers

Micrographs of normal pancreas, pancreatic intraepithelial neoplasia (precursors to pancreatic carcinoma) and pancreatic carcinoma. H&E stain.

Pancreatic carcinoma is thought to arise from progressive tissue changes to any of a number of types of precancerous cystic lesion in the pancreas. But by no means all such lesions progress to cancer, and the increased numbers detected incidentally with the increasing use of CT scans for other reasons are not all treated. Three types of precancerous lesion are recognized, in addition to pancreatic serous cystadenomas (SCNs), which are almost always benign. The first is pancreatic intraepithelial neoplasia, microscopic lesions of the pancreas, which are often found in autopsies of people with no diagnosed cancer. These may progress from low to high grade and then to a tumor. More than 90% of all grades have KRAS mutations, while in grades 2 and 3 the inactivation of CDKN2A and p53 by mutations and SMAD4 (the so-called "Mothers against decapentaplegic homolog 4") are increasingly often found.

Intraductal papillary mucinous neoplasms (IPMNs) are macroscopic lesions, which occur in about 2% of all adults, rising to about 10% by age 70. They also very often have KRAS mutations, in about 40-65% of cases, and in the GNAS Gs alpha subunit and RNF43, affecting the Wnt signaling pathway. Where these have been removed surgically, there is a considerably increased risk of pancreatic cancer developing subsequently.

The last type, pancreatic mucinous cystic neoplasms (MCNs) mainly occur in women, and may remain benign or progess to cancer. If they become large or cause symptoms they can usually be successfully removed by surgery.

The genetic events that cause ductal adenocarcinoma have been well characterized, and full exome sequencing has been done for the comon types of tumor. The most common alterations are KRAS mutations (95%), CDKN2A mutations/deletions (about 95%), TP53 inactivations (75%), SMAD4 deletions/mutations (50%), the last especially associated with a poor prognosis. SWI/SNF mutations/deletions occur in 35% of tumors. The genetic alterations in several other types of pancreatic cancer and precancerous lesions have also been researched.

Cross section of a human liver, taken at autopsy examination, showing multiple large pale tumor deposits. The tumor is an adenocarcinoma derived from a primary lesion in the body of the pancreas.

Pancreatic neuroendocrine tumors

Main article: Neuroendocrine tumor

Endocrine pancreatic tumors have been variously called islet cell tumors, pancreas endocrine tumors (PETs), and pancreatic neuroendocrine tumors (PNETs). The annual clinically recognized incidence is low, about five per one million person-years. However, autopsy studies incidentally identify PETs in up to 1.5% most of which would remain inert and asymptomatic. A problem with these figures is that the majority of PNETs are usually categorized as benign, but the definition and recognition of malignancy in pancreas endocrine tumors has been ambiguous. A small subset of endocrine pancreatic tumors are incontrovertible pancreatic endocrine cancers, that make up about 1% of pancreas cancers. Definitional migration has caused some complexity of PNET classification, which has adversely affected what is known about the epidemiology and natural history of these tumors.

The genes often found mutated in PanNETs are typically a different set from those in pancreatic adenocarcinoma, and for example KRAS mutation is normally absent. Instead common mutations affect MEN1, as in the inherited Wermer's syndrome, DAXX, mTOR and ATRX.

Prevention

Apart from not smoking, the American Cancer Society recommends keeping a healthy weight, and increasing consumption of fruits, vegetables, and whole grains, while decreasing consumption of red and processed meat, although there is no consistent evidence this will prevent or reduce pancreatic cancer specifically.

The results of a meta-analysis of randomized trials by Rothwell and colleagues indicate that taking a daily low-dose aspirin regimen for more than five years decreases the risk of developing pancreatic adenocarcinoma (ductal pancreatic cancer) by 75%.

Screening

It is generally agreed that general screening of large groups is not at present likely to be effective, and outside clinical trials there are no programmes for this. The European Society for Medical Oncology recommends regular screening with endoscopic ultrasound and MRI/CT imaging for those at high risk from inherited genetics, in line with other recommendations, which may also include CT.

Management

Exocrine cancer

The first and most crucial clinical decision to be made after diagnosis is whether surgical removal of the tumor is possible, as only this offers hope of a cure. This will require a tumor that has not metastasized, and will then depend on the location and spread of the tumor. In particular the tumor will be examined through CT to see how it relates to the major blood vessels passing close to the pancreas. An abutment of the tumor, defined as the tumor touching up to 180° of a blood vessel's circumference, may be operable, but encasement, defined as more 180° engaged, is not. The general health of the patient must also be assessed, though age in itself is not an obstacle to surgery.

Chemotherapy and, to a lesser extent, radiotherapy, are likely to be offered to most patients, whether or not surgery is possible. Management of pancreatic cancer should be in the hands of a multidisciplinary team including specialists in several aspects of oncology, and is therefore best conducted in larger centers.

Surgery

Diagram showing the parts removed with Whipple's operation

Surgery with the intention of a cure is only possible in at best 20% of new cases. The evidence as to whether the tumor can be fully removed, called resectability, is hard to assess, and it often turns out in surgery that it is not possible to successfully remove the tumor without damaging other vital tissues. Even when the operation appears to have been successful, it is still common for cancerous cells to be found at the edges of the tissue removed when examined microscopically by a pathologist (this will always be done), indicating the cancer has not been eliminated and will continue to develop.

To avoid surgery that turns out to be largely fruitless in this way, a diagnostic laparoscopy can be performed to enable a much clearer idea of the outcome of a full operation. Surgery can also be performed for palliation, if the malignancy is invading or compressing the duodenum or colon. In such cases, bypass surgery might overcome the obstruction and improve quality of life but is not intended as a cure.

The Whipple procedure is the most common attempted curative surgical treatment for cancers involving the head of the pancreas. This procedure involves removing the pancreatic head and the curve of the duodenum together (pancreato-duodenectomy), making a bypass for food from stomach to jejunum (gastro-jejunostomy) and attaching a loop of jejunum to the cystic duct to drain bile (cholecysto-jejunostomy). It can be performed only if the patient is likely to survive major surgery and if the cancer is localized without invading local structures or metastasizing. It can, therefore, be performed in only the minority of cases. Cancers of the tail of the pancreas can be resected using a procedure known as a distal pancreatectomy, which often includes splenectomy or removal of the spleen. This is today often done using keyhole or laparoscopic surgery.

After surgery, adjuvant chemotherapy with gemcitabine or 5-FU should be offered if the patient is fit after surgery. There has been controversy as to whether it is beneficial to add radiotherapy since the 1980s, and the European Society for Medical Oncology recommend that this should only be used for patients in clinical trials. However it is more likely to be used in the USA.

Those with inoperable pancreatic cancer may have significant abdominal pain. A celiac plexus block (CPB), which destroys the nerves that transmit pain from the abdomen, is a safe and effective way to reduce the pain. CPB generally reduces the need to use pain killers like opioids, which have significant negative side effects.

• 
  Diagram showing how the pancreas and bowel are joined back together after Whipple's operation
• 
  Diagram showing the area to be removed for pylorus-preserving pancreaticoduodenectomy
• 
  Diagram showing the pancreas joined to the small bowel after pylorus preserving surgery for pancreatic cancer
• 
  Diagram showing how the bowel is joined back together after a total pancreatectomy

Radiation

The role of radiation therapy after potentially curative surgery has been controversial for many years, with a continuing tendency for clinicians in the US to be more ready to use adjuvant radiation therapy than those in Europe. Many clinical trials since the 1980s, testing a variety of treatment regimes, have failed to settle the matter conclusively.

Chemotherapy

In people not suitable for resection with curative intent, palliative chemotherapy may be used to improve quality of life and gain a modest survival benefit. Gemcitabine was approved by the United States Food and Drug Administration in 1997, after a clinical trial reported improvements in quality of life and a 5-week improvement in median survival duration in patients with advanced pancreatic cancer. This marked the first FDA approval of a chemotherapy drug primarily for a nonsurvival clinical trial endpoint. Gemcitabine is administered intravenously on a weekly basis.

Chemotherapy using gemcitabine alone was the standard for the years following, as a number of trials testing it in varying dosage regimes and in combination with other drugs failed to demonstrate significantly better outcomes. However the combination of gemcitabine with Erlotinib was found to increase survival, and Erlotinib was licensed by the FDA for use in pancreatic cancer. The FOLFIRINOX chemotherapy regimen using four drugs was found more effective than gemcitabine, but with serious side effects, and thus only suitable for patients with good performance status. This is also true of protein-bound paclitaxel or nab-paclitaxel, which was licensed by the FDA in 2013 for this purpose. By the end of 2013, both FOLFIRINOX and nab-paclitaxel were regarded as good choices for those patients who were able to withstand the side-effects, with gemcitabine remaining an option for those who were not. A head to head trial between the two new options is awaited, and trials investigating other variations continue. However, the changes of the last few years have only increased average survival times by a few months.

Neuroendocrine tumors

Main article: Neuroendocrine tumor

Treatment of pancreatic endocrine tumors, including the less common malignant tumors, may include a number of approaches. Watchful waiting of small tumors identified incidentally, for example on a computed tomography (CT) scan performed for other purposes, may conceptually not always need intervention, but the criteria for watchful waiting are unclear.

Tumors within the pancreas only (localized tumors), or with limited metastases, for example to the liver, may be removed by surgery. The type of surgery depends on the tumor location, and the degree of spread to lymph nodes. For localized tumors, the surgical procedure may be much less extensive than the types of surgery used to treat pancreatic adenocarcinoma described above, but otherwise surgical procedures are similar to those for exocrine tumors. The range of possible outcomes vary greatly; some types have a very high survival rate after surgery while others have a poor outlook. As all this group are rare, treatment should be undertaken in a specialized center with experience of them.

Standard cytotoxic chemotherapy, that damages healthy cells as well as the cancerous ones, is generally not very effective for PNETs, but may be used when other drug treatments fail to prevent the disease progressing. If the tumor is not amenable to surgical removal and is causing symptoms by secreting functional hormones, targeted medication for PNETs can be effective, both in reducing symptoms and slowing the progression of the disease. These are covered in more detail in the relevant section of that article.

For functioning tumors a class of drugs called somatostatin analogs are effective in reducing the excessive production of hormones and the associated problems. One of these, octreotide, is often used to lessen the symptoms, and sometimes also slows tumor growth. Everolimus and sunitinib are both licensed for such cases, and trials are exploring their combination with octreotide.

Radiation therapy is occasionally used if there is pain due to anatomic extension, such as metastasis to bone. Radiolabeled hormone: some PNETs absorb a hormone called norepinephrine and these may respond to nuclear medicine medication, radiolabeled MIBG therapy (or, experamentally, other hormones), given intravenously. Radiofrequency ablation (RFA), cryoablation, hepatic artery embolization.

Palliative care

Palliative care is medical care which focuses on treatment of symptoms from serious illness, like cancer, and improving quality of life. Because pancreatic adenocarcinoma, the most common type of pancreatic cancer, is one of the most aggressive cancers, it is usually diagnosed after it has progressed to an advanced stage, and there are fewer treatment options compared to other cancers, palliative care as a treatment of symptoms is often the only treatment possible.

Palliative care will focus not on treating the underlying cancer, but on treating symptoms such as pain or nausea, and can assist in decision making such as when or if hospice care will be beneficial. Pain can be managed with medications such as opioids or through procedural intervention such as celiac plexus blocks, which alters the nerves that may be causing pain. Other symptoms/complications that can be treated with palliative surgery are biliary or intestinal obstruction. Palliative care can also help treat depression that often comes with diagnosis of pancreatic cancer, and may indeed be a cause of it.

Both surgery and advanced inoperable tumors often produce digestive system disorders from a lack of the exocrine products of the pancreas (exocrine insufficiency). These can be treated by taking pancreatin which contains manufactured pancreatic enzymes, and is best taken with food. Difficulty in emptying the stomach (delayed gastric emptying) is common and can be a serious problem, involving time in hospital. Treatment may involve a variety of approaches, including draining the stomach by nasogastric aspiration and drugs called proton-pump inhibitors or H2 antagonists, which both reduce production of gastric acid.

Prognosis

Outcomes in pancreatic cancers according to clinical stage

Clinical stage	Five-year survival (%) - U.S., diagnoses 1992-98
	Exocrine pancreatic cancer	neuroendocrine treated with surgery
IA / I	14	61
IB	12
IIA / II	7	52
IIB	5
III	3	41
IV	1	16

Pancreatic adenocarcinoma and the other less common exocrine cancers have a very poor prognosis, as they are resistant to treatment and usually cause no early symptoms. Therefore they are normally diagnosed at a late stage, when the cancer is already locally advanced or has spread to other parts of the body. Outcomes with pancreatic endocrine tumors, many of which are benign and completely without clinical symptoms, are much better, and even those cases not able to be treated by surgery have a 5-year survival rate of 16%, although the outlook greatly varies according to the type.

For locally advanced and metastatic pancreatic adenocarcinoma, which collectively represent over 80% to 85-90% of cases, numerous recent trials comparing chemotherapy regimes have shown increased average survival rates, but not to above one year. Together with lung cancer, pancreatic cancer as a whole has shown the least improvement in US survival rates of all common cancers over the three decades to 2013, although 5-year survival has improved from 2% in cases diagnosed in 1975-77, and 4% in 1987-89 diagnoses, to 6% in 2002-08.

Distribution

Age-standardized death from pancreatic cancer per 100,000 inhabitants in 2004.

  no data

  <1

  1

  2

  3

  4

  5

  6

  7

  8

  9

  10

  >10

Globally, as of 2012, pancreatic cancer resulted in 330,000 deaths, up from 310,000 in 2010 and 200,000 in 1990. In 2014, an estimated 46,000 people in the US are expected to be diagnosed with pancreatic cancer and 40,000 to die of it. Pancreatic cancer has one of the highest fatality rates of all cancers, and is the fourth-highest cancer killer among both men and women worldwide. Although it accounts for only 2.5% of new cases, pancreatic cancer is responsible for 6% of cancer deaths each year.

The rates of incidence vary greatly, with those in the developed world generally being higher. The disease is more common in men than women, though the difference in rates has narrowed over recent decades, probably reflecting earlier increases in female smoking. In the United States the risk for African Americans is over 50% greater than for whites, but the rates in Africa, like East Asia, are much lower than those in North America or Europe. The United States, Central and eastern Europe, and Argentina and Uruguay all have high rates of incidence.

Pancreatic cancer is the tenth most common cancer in the UK (around 8,800 people were diagnosed with the disease in 2011), and it is the fifth most common cause of cancer death (around 8,700 people died in 2012).

History

The first reported partial pancreaticoduodenectomy was performed by the Italian surgeon Alessandro Codivilla in 1898, but the patient only survived 18 days before succumbing to complications. Early operations were compromised partly because of mistaken beliefs that it was essential for life to preserve the duodenum and, at first, the flow of pancreatic juices. Later it was thought, also mistakenly, that the pancreatic duct could simply be tied up without serious adverse effects; in fact it will very often burst under pressure from the juices later on. In the 1900s, after some more unsuccessful operations by other surgeons, experimental procedures were tried on corpses by French surgeons.

In 1912 the German surgeon Walther Kausch was the first to remove large parts of the duodenum and pancreas together (en bloc). This was in Breslau, now Wrocław in Poland. In 1918 in had been demonstrated in operations on dogs that total removal of the duodenum was not essential for life, but this was not reported in human surgery until 1935, when the American surgeon Allen Whipple published the results of a series of three operations at Columbia Presbyterian Hospital in New York. Only one of the patients had the total removal of the duodenum, but he survived for two years before dying of metastasis to the liver. The first operation was unplanned, as cancer was only discovered in the operating theatre. Whipple's success showed the way for the future, but the operation remained a difficult and dangerous one until recent decades. He published several refinements to his procedure, including the first total removal of the duodenum in 1940, but he only performed a total of 37 operations.

The discovery of vitamin K in 1940 and the development of blood transfusion as an everyday process both improved post-operative survival, but about 25% of patients never left hospital alive as late as the 1970s. In the 1970s a group of American surgeons wrote urging that the procedure was too dangerous and should be abandoned. Since then outcomes in larger centers have improved considerably, and mortality from the operation is often less than 4%. In 2006 a series of One Thousand Consecutive Pancreaticoduodenectomies by a single surgeon from Johns Hopkins Hospital was published, performed between 1969 and 2003. The rate of these operations had increased steadily over this period, with only three of them before 1980, and the median operating time reduced from 8.8 hours in the 1970s to 5.5 hours in the 2000s, and mortality within 30 days or in hospital was only 1%. Another series of 2050 operations at the Massachusetts General Hospital between 1941 and 2011 showed a similar picture of improvement.

As described above, the very small precancerous neoplasms for many pancreatic cancers are being detected at greatly increased rates by modern medical imaging. One type, the intraductal papillary mucinous neoplasm (IPMN) was first described by Japanese researchers in 1982; "For the next decade, little attention was paid to this report; however, over the subsequent 15 years, there has been a virtual explosion in the recognition of this tumor".

Research

As of 2014, worldwide efforts are under way to understand pancreatic cancer on many levels, and there are several fundamental unanswered questions. Research on pancreatic cancer has been recognized as an area in need of prioritization due to limited progress over recent decades.

The nature of the genetic changes that lead to the disease are being intensely scrutinized, for example by the Australian Pancreatic Genome Initiative as part of the International Cancer Genome Consortium. These and others have uncovered the key role played by genes such as KRAS and p53 in the disease’s development. A key question is the timing of key events in the disease’s progression – particularly how and when it spreads (metastasizes), and how these are affected by lifestyle risk factors such as obesity and smoking.

Research on early detection is ongoing, for example the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (EUROPAC) trial is aiming to determine whether regular screening is appropriate for people with a family history of the disease, or who have hereditary pancreatitis.

Parallel to this, efforts are underway to develop new drugs to target the disease, or to test existing drugs that are currently not used to treat it. Some of these involve treatments to target cancer cells themselves using targeted therapies. Others aim to target the tissue surrounding the pancreatic tumour (the stroma or microenvironment). The availability of new genetically engineered mouse models has substantially advanced this research in recent years. A third key strand of research on treating the disease is immunotherapy – particularly using oncolytic viruses.

Another key area of interest is in assessing whether keyhole surgery (laparoscopy) would be better than Whipple’s Procedure (pancreaticoduodenectomy) in treating the disease surgically, particularly in terms of recovery time. The limited success of outcomes after surgery has led to a number of trials that were running in 2014 to test outcomes using chemotherapy or radiochemotherapy before surgery. This had previously not been found to be helpful, but is being trialed again, using drug combinations which have emerged from the many trials of post-operative therapies, such as FOLFIRINOX.

See also

• Gastrointestinal cancer
• Pancreatic Cancer Action (organization in the UK)
• Lustgarten Foundation for Pancreatic Cancer Research (organization in the US)

External links

• Pancreatic cancer at Curlie