|Classification and external resources|
A basal cell carcinoma. Note the pearly appearance and telangiectasia.
|eMedicine||article/276624, article/870538, article/1100753, article/1965430|
Skin cancers (skin neoplasms) are named after the type of skin cell from which they arise. Basal cell cancer originates from the lowest layer of the epidermis, and is the most common but least dangerous skin cancer. Squamous cell cancer originates from the middle layer, and is less common but more likely to spread and, if untreated, become fatal. Melanoma, which originates in the pigment-producing cells (melanocytes), is the least common, but most aggressive, most likely to spread and, if untreated, become fatal. Still, melanoma has one of the higher survival rates among major cancer, with over 75% of patients surviving 10 years in the UK during 2005-2007.
In the UK in 2010, 12,818 people were diagnosed with malignant melanoma, and about 100,000 people were diagnosed with non-melanoma skin cancer. There were 2,746 deaths from skin cancer, 2,203 from malignant melanoma and 546 from non-malignant melanoma. In the US in 2008, 59,695 people were diagnosed with melanoma, and 8,623 people died from it.
|Basal cell carcinoma||Note the pearly translucency to fleshy color, tiny blood vessels on the surface, and sometime ulceration which can be characteristics. The key term is translucency.|
|Squamous cell carcinoma||Commonly presents as a red, crusted, or scaly patch or bump. Often a very rapid growing tumor.|
|Malignant melanoma||The common appearance is an asymmetrical area, with an irregular border, color variation, and often greater than 6 mm diameter.|
Basal cell carcinomas are present on sun-exposed areas of the skin, especially the face. They rarely metastasize and rarely cause death. They are easily treated with surgery or radiation. Squamous cell carcinomas (SCC) are common, but much less common than basal cell cancers. They metastasize more frequently than BCCs. Even then, the metastasis rate is quite low, with the exception of SCC of the lip, ear, and in immunosuppressed patients. Melanomas are the least frequent of the 3 common skin cancers. They frequently metastasize, and could potentially cause death once they spread.
Less common skin cancers include: Dermatofibrosarcoma protuberans, Merkel cell carcinoma, Kaposi's sarcoma, keratoacanthoma, spindle cell tumors, sebaceous carcinomas, microcystic adnexal carcinoma, Pagets's disease of the breast, atypical fibroxanthoma, leimyosarcoma, and angiosarcoma.
The BCC and the SCCs often carry a UV-signature mutation indicating that these cancers are caused by UV-B radiation via the direct DNA damage. However the malignant melanoma is predominantly caused by UV-A radiation via the indirect DNA damage.The indirect DNA damage is caused by free radicals and reactive oxygen species. Research indicates that the absorption of three sunscreen ingredients into the skin, combined with a 60-minute exposure to UV, leads to an increase of free radicals in the skin, if applied in too little quantities and too infrequently. However, the researchers add that newer creams often do not contain these specific compounds, and that the combination of other ingredients tends to retain the compounds on the surface of the skin. They also add the frequent re-application reduces the risk of radical formation.
Signs and symptoms
There are a variety of different skin cancer symptoms. These include changes in the skin that do not heal, ulcering in the skin, discolored skin, and changes in existing moles, such as jagged edges to the mole and enlargement of the mole.
Basal cell carcinoma
Basal cell carcinoma usually presents as a raised, smooth, pearly bump on the sun-exposed skin of the head, neck or shoulders. Sometimes small blood vessels can be seen within the tumor. Crusting and bleeding in the center of the tumor frequently develops. It is often mistaken for a sore that does not heal. This form of skin cancer is the least deadly and with proper treatment can be completely eliminated, often without scarring.
Squamous cell carcinoma
Squamous cell carcinoma is commonly a red, scaling, thickened patch on sun-exposed skin. Some are firm hard nodules and dome shaped like keratoacanthomas. Ulceration and bleeding may occur. When SCC is not treated, it may develop into a large mass. Squamous cell is the second most common skin cancer. It is dangerous, but not nearly as dangerous as a melanoma.
Most melanomas are brown to black looking lesions. Unfortunately, a few melanomas are pink, red or fleshy in color; these are called amelanotic melanomas. These tend to be more aggressive. Warning signs of malignant melanoma include change in the size, shape, color or elevation of a mole. Other signs are the appearance of a new mole during adulthood or new pain, itching, ulceration or bleeding. An often-used mnemonic is "ABCDE", where A= asymmetrical, B= "borders" (irregular= "Coast of Maine sign"), C= "color" (variegated), D= "diameter" (larger than 6 mm—the size of a pencil eraser) and E= "evolving."
- Some genetic syndromes including congenital melanocytic nevi syndrome which is characterized by the presence of nevi (birthmarks or moles) of varying size which are either present at birth, or appear within 6 months of birth. Nevi larger than 20 mm (3/4") in size are at higher risk for becoming cancerous.
- Chronic non-healing wounds. These are called Marjolin's ulcers based on their appearance, and can develop into squamous cell carcinoma.
- Ionizing radiation, environmental carcinogens, artificial UV radiation (e.g. tanning beds), aging, and light skin color. It is believed that tanning beds are the cause of hundreds of thousands of basal and squamous cell carcinomas. The World Health Organization now places people who use artificial tanning beds in its highest risk category for skin cancer.
- The use of many immunosuppressive medication increase the risk of skin cancer. Cyclosporin A, a calcineurin inhibitor for example increases the risk approximately 200 times, and azathioprine about 60 times.
Squamous cell carcinoma is a malignant epithelial tumor which originates in epidermis, squamous mucosa or areas of squamous metaplasia.
Macroscopically, the tumor is often elevated, fungating, or may be ulcerated with irregular borders. Microscopically, tumor cells destroy the basement membrane and form sheets or compact masses which invade the subjacent connective tissue (dermis). In well differentiated carcinomas, tumor cells are pleomorphic/atypical, but resembling normal keratinocytes from prickle layer (large, polygonal, with abundant eosinophilic (pink) cytoplasm and central nucleus).
Their disposal tends to be similar to that of normal epidermis: immature/basal cells at the periphery, becoming more mature to the centre of the tumor masses. Tumor cells transform into keratinized squamous cells and form round nodules with concentric, laminated layers, called "cell nests" or "epithelial/keratinous pearls". The surrounding stroma is reduced and contains inflammatory infiltrate (lymphocytes). Poorly differentiated squamous carcinomas contain more pleomorphic cells and no keratinization.
Sunscreen is effective and thus recommended to prevent melanoma and squamous cell carcinoma. There is little evidence that it is effective in preventing basal cell carcinoma. Other advice to reduce rates of skin cancer includes: avoiding sunburning, wearing protective clothing, sunglasses and hats, and attempting to avoid sun exposure or periods of peak exposure. The U.S. Preventive Services Task Force recommends that people aged between 9 and 25 years of age be advised to avoid ultraviolet light.
The risk of developing skin cancer can be reduced through a number of measures including: decreasing indoor tanning and mid day sun exposure, increasing the use of sunscreen, and avoiding the use of tobacco products.
There is insufficient evidence either for or against screening for skin cancers. Vitamin supplements and antioxidant supplements have not been found to have an effect in prevention. Evidence for a benefit from dietary measures is tentative.
Treatment is dependent on type of cancer, location of the cancer, age of the patient, and whether the cancer is primary or a recurrence. Treatment is also determined by the specific type of cancer. For a small basal cell cancer in a young person, the treatment with the best cure rate (Mohs surgery or CCPDMA) might be indicated. In the case of an elderly frail man with multiple complicating medical problems, a difficult to excise basal cell cancer of the nose might warrant radiation therapy (slightly lower cure rate) or no treatment at all. Topical chemotherapy might be indicated for large superficial basal cell carcinoma for good cosmetic outcome, whereas it might be inadequate for invasive nodular basal cell carcinoma or invasive squamous cell carcinoma.. In general, melanoma is poorly responsive to radiation or chemotherapy.
For low-risk disease, radiation therapy (external beam radiotherapy or brachytherapy), topical chemotherapy (imiquimod or 5-fluorouracil) and cryotherapy (freezing the cancer off) can provide adequate control of the disease; both, however, may have lower overall cure rates than certain type of surgery. Other modalities of treatment such as photodynamic therapy, topical chemotherapy, electrodesiccation and curettage can be found in the discussions of basal cell carcinoma and squamous cell carcinoma.
Mohs' micrographic surgery (Mohs surgery) is a technique used to remove the cancer with the least amount of surrounding tissue and the edges are checked immediately to see if tumor is found. This provides the opportunity to remove the least amount of tissue and provide the best cosmetically favorable results. This is especially important for areas where excess skin is limited, such as the face. Cure rates are equivalent to wide excision. Special training is required to perform this technique. An alternative method is CCPDMA and can be performed by a pathologist not familiar with Mohs surgery.
Currently, surgical excision is the most common form of treatment for skin cancers. The goal of reconstructive surgery is restoration of normal appearance and function. The choice of technique in reconstruction is dictated by the size and location of the defect. Excision and reconstruction of facial skin cancers is generally more challenging due to presence of highly visible and functional anatomic structures in the face.
When skin defects are small in size, most can be repaired with simple repair where skin edges are approximated and closed with sutures. This will result in a linear scar. If the repair is made along a natural skin fold or wrinkle line, the scar will be hardly visible. Larger defects may require repair with a skin graft, local skin flap, pedicled skin flap, or a microvascular free flap. Skin grafts and local skin flaps are by far more common than the other listed choices.
Skin grafting is patching of a defect with skin that is removed from another site in the body. The skin graft is sutured to the edges of the defect, and a bolster dressing is placed atop the graft for seven to ten days, to immobilize the graft as it heals in place. There are two forms of skin grafting: split thickness and full thickness. In a split thickness skin graft, a shaver is used to shave a layer of skin from the abdomen or thigh. The donor site, regenerates skin and heals over a period of two weeks. In a full thickness skin graft, a segment of skin is totally removed and the donor site needs to be sutured closed.
Split thickness grafts can be used to repair larger defects, but the grafts are inferior in their cosmetic appearance. Full thickness skin grafts are more acceptable cosmetically. However, full thickness grafts can only be used for small or moderate sized defects.
Local skin flaps are a method of closing defects with tissue that closely matches the defect in color and quality. Skin from the periphery of the defect site is mobilized and repositioned to fill the deficit. Various forms of local flaps can be designed to minimize disruption to surrounding tissues and maximize cosmetic outcome of the reconstruction. Pedicled skin flaps are a method of transferring skin with an intact blood supply from a nearby region of the body. An example of such reconstruction is a pedicled forehead flap for repair of a large nasal skin defect. Once the flap develops a source of blood supply form its new bed, the vascular pedicle can be detached.
The mortality rate of basal cell and squamous cell carcinoma are around 0.3% causing 2000 deaths per year in the US. In comparison the mortality rate of melanoma is 15-20% and it causes 6500 deaths per year.:29,31 Even though it is much less common, malignant melanoma is responsible for 75% of all skin cancer-related deaths.
A study of the incidence of non-melanoma skin cancer from 1992 to 2006 in the United States was performed by the dermatologist Howard Rogers, MD, PhD, and his colleagues based on the evaluation of Medicare databases. The results of their research showed that cases of non-melanoma skin cancer rose an average of 4.2% a year.
More than 3.5 million cases of skin cancer are diagnosed annually in the United States, which makes it the most common form of cancer in that country. According to the Skin Cancer Foundation, one in five Americans will develop skin cancer at some point of their lives. The first most common form of skin cancer is basal cell carcinoma, followed by the squamous cell carcinoma. Although the incidence of many cancers in the United States is falling, the incidence of melanoma keeps growing, with approximately 68,729 melanomas diagnosed in 2004 according to reports of the National Cancer Institute.
The survival rate for patients with melanoma depends upon when they start treatment. The cure rate is very high when melanoma is detected in early stages, when it can easily be removed surgically. The prognosis is less favorable if the melanoma has spread to other parts of the body.
In the UK, 84,500 non-melanoma skin cancers were registered in 2007 although a study estimated that at least 100,000 cases are diagnosed each year. Most NMSCs were basal cell carcinomas or squamous cell carcinomas. In 2007, 10,672 cases of malignant melanoma were diagnosed.
Australia and New Zealand exhibits one of the highest rates of skin cancer incidence in the world, almost four times the rates registered in the United States, the UK and Canada. Around 434,000 people receive treatment for non-melanoma skin cancers and 10,300 are treated for melanoma. Melanoma is the common type of cancer in people between 15–44 years in both countries. This is largely due to the ozone hole located over the Tasman Sea, making prolonged unprotected outdoor sun exposure very dangerous. The risk of skin cancer in Australia is predicted to increase. The reason given for the increase is that ozone levels are not expected to recover to pre-depletion levels until the middle of this century, UV levels are expected to continue to rise. Combined with Australians favoring an outdoor life-style, when temperatures are warmer, under high levels of UV, the associated risk of skin cancer will increase.
- Merck Manual of Diagnosis and Therapy
- Kasper, Dennis L; Braunwald, Eugene; Fauci, Anthony; et al. (2005). Harrison's Principles of Internal Medicine, 16th ed. New York: McGraw-Hill. ISBN 0-07-139140-7 Check
- CancerStats — Skin cancer survival, Cancer Research UK
- CancerStats — Skin Cancer statistics UK Cancer Research UK
- Marks R (January 1995). "An overview of skin cancers. Incidence and causation". Cancer 75 (2 Suppl): 607–12. doi:10.1002/1097-0142(19950115)75:2+<607::AID-CNCR2820751402>3.0.CO;2-8. PMID 7804986.
- "Malignant Melanoma: eMedicine Dermatology".
- Hanson Kerry M.; Gratton Enrico; Bardeen Christopher J (2006). "Sunscreen enhancement of UV-induced reactive oxygen species in the skin". Free Radical Biology and Medicine 41 (8): 1205–1212. doi:10.1016/j.freeradbiomed.2006.06.011. PMID 17015167.
- Bickle K, Glass, LF, Messina, JL, Fenske, NA, Siegrist, K (Mar 2004). "Merkel cell carcinoma: a clinical, histopathologic, and immunohistochemical review.". Seminars in cutaneous medicine and surgery 23 (1): 46–53. PMID 15095915.
- Narayanan DL, Saladi, RN, Fox, JL (Sep 2010). "Ultraviolet radiation and skin cancer.". International Journal of Dermatology 49 (9): 978–86. doi:10.1111/j.1365-4632.2010.04474.x. PMID 20883261.
- Saladi RN, Persaud, AN (Jan 2005). "The causes of skin cancer: a comprehensive review.". Drugs of today (Barcelona, Spain : 1998) 41 (1): 37–53. doi:10.1358/dot.2005.41.1.875777. PMID 15753968.
- Wehner, MR; Shive, ML; Chren, MM; Han, J; Qureshi, AA; Linos, E (2012 Oct 2). "Indoor tanning and non-melanoma skin cancer: systematic review and meta-analysis.". BMJ (Clinical research ed.) 345: e5909. PMID 23033409.
- Arndt, K.A.(2010).Skin Care and Repair.Chestnut Hill, MA:Harvard Health Publications.
- Kuschal C, Thoms, KM; Schubert, S; Schäfer, A; Boeckmann, L; Schön, MP; Emmert, S (Jan 2012). "Skin cancer in organ transplant recipients: effects of immunosuppressive medications on DNA repair.". Experimental Dermatology 21 (1): 2–6. doi:10.1111/j.1600-0625.2011.01413.x. PMID 22151386.
- ""Squamous cell carcinoma (epidermoid carcinoma) — skin" pathologyatlas.ro". Retrieved 2007-07-21.
- Kanavy HE, Gerstenblith MR (December 2011). "Ultraviolet radiation and melanoma". Semin Cutan Med Surg 30 (4): 222–8. doi:10.1016/j.sder.2011.08.003. PMID 22123420.
- Burnett ME, Wang SQ (April 2011). "Current sunscreen controversies: a critical review". Photodermatol Photoimmunol Photomed 27 (2): 58–67. doi:10.1111/j.1600-0781.2011.00557.x. PMID 21392107.
- Kütting B, Drexler H (December 2010). "UV-induced skin cancer at workplace and evidence-based prevention". Int Arch Occup Environ Health 83 (8): 843–54. doi:10.1007/s00420-010-0532-4. PMID 20414668.
- Council on Environmental H, Section on, Dermatology, Balk, SJ (Mar 2011). "Ultraviolet radiation: a hazard to children and adolescents.". Pediatrics 127 (3): 588–97. doi:10.1542/peds.2010-3501. PMID 21357336.
- Lin JS, Eder, M, Weinmann, S (Feb 2011). "Behavioral counseling to prevent skin cancer: a systematic review for the U.S. Preventive Services Task Force.". Annals of internal medicine 154 (3): 190–201. doi:10.1059/0003-4819-154-3-201102010-00009. PMID 21282699.
- Lin JS, Eder, M, Weinmann, S (2011). "Behavioral counseling to prevent skin cancer: a systematic review for the U.S. Preventive Services Task Force.". Annals of internal medicine 154 (3): 190–201. doi:10.1059/0003-4819-154-3-201102010-00009. PMID 21282699.
- "Screening for Skin Cancer". U.S. Preventive Services Task Force. 2009.
- Chang YJ, Myung, SK, Chung, ST, Kim, Y, Lee, EH, Jeon, YJ, Park, CH, Seo, HG, Huh, BY (2011). "Effects of vitamin treatment or supplements with purported antioxidant properties on skin cancer prevention: a meta-analysis of randomized controlled trials.". Dermatology (Basel, Switzerland) 223 (1): 36–44. doi:10.1159/000329439. PMID 21846961.
- Jensen, JD; Wing, GJ; Dellavalle, RP (2010 Nov-Dec). "Nutrition and melanoma prevention.". Clinics in dermatology 28 (6): 644–9. doi:10.1016/j.clindermatol.2010.03.026. PMID 21034988.
- Doherty, Gerard M.; Mulholland, Michael W. (2005). Greenfield's Surgery: Scientific Principles And Practice. Baltimore: Williams & Wilkins. ISBN 0-7817-5626-X.
- Maurice M Khosh, MD, FACS. "Skin Grafts, Full-Thickness". eMedicine.
- Skin Cancer Reconstruction
- C. C. Boring, T. S. Squires and T. Tong (1991). "Cancer statistics, 1991". SA Cancer Journal for Clinician 41 (1): 19–36. doi:10.3322/canjclin.41.1.19. PMID 1984806.
- Jerant AF, Johnson JT, Sheridan CD, Caffrey TJ (July 2000). "Early Detection and Treatment of Skin Cancer". American Family Physician 62 (2): 357–68, 375–6, 381–2. PMID 10929700.
- "WHO Disease and injury country estimates". World Health Organization. 2009. Retrieved Nov. 11, 2009.
- "Epidemic of Skin Cancer in the U.S.?". Retrieved 2010-07-02.
- "Skin Cancer Facts". Retrieved 2010-07-02.
- "Malignant Melanoma Cancer". Retrieved 2010-07-02.
- "Skin Cancer – UK Incidence Statistics". Retrieved 2010-07-02.
- "Skin Cancer Facts and Figures". Retrieved 2010-07-02.
- Green, Adèle (2012-09-01). "Skin Cancer Prevention: Recent Evidence from Randomized Controlled Trials". Current Dermatology Reports 1 (3): 123–130. doi:10.1007/s13671-012-0015-9.
|Wikimedia Commons has media related to: Skin cancers|