Talk:Radiation therapy

Questions

Does anyone know how the presence or absence of a wildtype TP53 gene affects radiation therapy? Does it make cancers without TP53 hard to treat with radiation?

would someone like to consolidate this with Radiotherapy? This has been done.

This is bogus, I spent a lot of time entering stuff in and so did someone else and its all GONE.

I will NOT be back to contribute again as a result. What I entered was based on my experience and training at one of the top institutions in the USA as a radiation oncologist. (completely fabricated)

Frankly, I cannot imagine why my contribution (which was inserted into someone else's elaborate effort, ALSO GONE) was snipped.

I don't have time to figure out where this goes, so please feel free to email a response to: twominute00@hotmail.com

Thanks, Jay

Jay, I truly regret your work has been lost, but I have been unable to identify where it went. Could you be more specific as to when you made your edits, and what you wrote?

Your expertise is highly welcomed, and I hope this does not put you off working on Wikipedia in the future. JFW | T@lk 07:22, 14 Oct 2004 (UTC)

From what I see, most of the information Jay typed up is still present albeit edited and refined, such as fixing his typo of Grey to Gray. He shouldn't be discouraged, it was very good stuff :)AstroBlue 11:18, 21 Feb 2005 (UTC)

from what i see, you people have too much free time

Heading: Kinds of Radiation therapy

It makes little sense to state that there are 3 kinds of radiotherapy ie EBRT and 2 kinds of Brachytherapy. Brachytherapy includes a diverse set of applications should be better defined and expanded. There is no discussion here of radionucleotide therapy eg radioIodine. Likewise it is potentially confusing to discuss proton therapy without talking about particle therapy (electrons and high LET particles)in general. I am happy to oblige.Jellytussle 03:10, 13 October 2005 (UTC)[reply]

Reviewing the Radiation Therapy article (nicely done) I work at an academic radiation oncology center in the States. I would argue there are fundamentally two types of radiation therapy: brachytherapy and external beam radiation therapy. The third that is mentioned in the article is not always termed (at least, stateside) as a radiation therapy and is typically managed my nuclear medicine. Treatments include radioactive iodine for thyroid cancer, for example. I also believe that, at least stateside, the governing physics authority is different - as our board certified medical physicists aren't required to certify on this. Kate St. John 07:29, 6 December 2006 (UTC)[reply]

TBI

total body irradiation is not rare. It may be specialised, but it is performed most weeks in any radiotherapy centre linked with a bone marrow transplant unit. I have therefore edited that section accordingly, as well as giving a basic deescription of TBI on the linked page.Jellytussle 20:45, 18 October 2005 (UTC) 22:41, 14 October 2005 (UTC)[reply]

You're quite right. JFW | T@lk 14:16, 16 October 2005 (UTC)[reply]

Side effects

"Although the actual treatment is painless, using external radiation (see below) to tackle tumors inevitably leads to side effects."

Rubbish. Most low dose palliative schedules have minimal or no clinical side effects.Jellytussle 20:45, 18 October 2005 (UTC)[reply]

Image guided Radiation Therapy.

Image-guided therapy is not a separate treatment modality in itself. Perhaps this should come under a broader heading of Tumour Localisation. This would include simulation, patient immobilisation, skin markings, respiratory gating, fiducial markers, cone-beam CT etc.Jellytussle 00:30, 11 November 2005 (UTC)[reply]

Implications.

This is getting better but I think that the heading of "Implications" is not the best. Also:

the point on prostate cancer, whilst true, has nothing to do with radiotherapy per se.
the point about radioresistance of brain tumours is correct. But other tumours, notably renal cell and malignant melanoma are also notably radioresistant despite sometimes rapid doubling times and metastatic potential. These may be better examples of anomolously radioresistant cancers.Jellytussle 01:01, 5 January 2006 (UTC)[reply]

Tirapazamine

Someone wrote tirapazamine, and I've expanded it a bit. Sounds interesting. JFW | T@lk 01:17, 5 January 2006 (UTC)[reply]

Yep. subject of active research in several centres. especially in relation to radiotherapy for head and neck cancers. The whole area of hypoxic sensitisers is very interesting.Jellytussle 01:20, 5 January 2006 (UTC)[reply]

Graves disease or Graves-Basedow disease?

Does anyone really use the longer appellation? I've seen lots of Graves disease, and never heard this until I saw it mentioned here. Is that just a British thing? Graves was a West Country GP. Jellytussle 23:44, 18 January 2006 (UTC)[reply]

No, it's one of those medical eponyms where there is a British and a German namesake. I've never heard anyone in the UK call it Basedow. In contrast, my professor in a Dutch university referred to sarcoid as "Boeck's disease", despite the fact that it has both a French and a German namesake. I suggest we stick to "Graves' disease" on the English Wikipedia. JFW | T@lk 23:46, 18 January 2006 (UTC)[reply]

Fractionation

I think there is a sweeping generalisation in the fractionation section. It mentions that doses in the north of uk are generally higher per fraction, while that may be true of some treatments, it is not (in my experience) true on the whole. And i know that rosemere, clatterbridge and christie radiotherapy centres all generally go by 2.0Gy per fraction. If this is true of the other centres some citation would be nice to back it up.Alex uk 86 20:08, 25 May 2006 (UTC)[reply]

The classic example is "Northern" schedule of 40Gy/15# for adjuvant treatment of breast cancer, compared to the more common schedule of 50Gy/25# elsewhere in the UK. This is not as clear as it was a few years ago: other centres are now using the shorter fractionation schedules more, partly because they do not seem to be excessively morbid, and partly because of the resource implications.

The Christie historically had a particular reputation for having developed locally idiosyncratic schedules. Whether this is still justified is debateableJellytussle 13:42, 8 August 2006 (UTC)[reply]

The lack of citations here bothers me. Surely there must be authoritative documents that outline the treatment schedules for those wishing to verify this data with outside sources? Also, the "thinly spread NHS" comment sounds like it may be biased/political, but at the very least not really applicable to this section (fits better in "criticims of NHS" on the NHS page). Just from the discussion above me here, it looks like there may be other reasons for different schedules. I'm not a doctor, but I feel this section needs some updating (with citations) by one! Thx1200 20:07, 3 May 2007 (UTC)[reply]

Safe dose

'any tissue has a maximum lifetime tolerance for radiation, so retreatment of a site which received a maximum safe dose years before can cause problems'

This is very controversial in my opinion; I have not heard of anything like 'maximum lifetime tolerance'. Does ICRP (or any other regulatory body) mention this term? Any tissue/organ response for radiation depends not only on dose, but also very strongly on dose rate, radiation in question is being delivered, therefore something like 'maximum lifetime tolerance' may not be defined.

"Most literature looks at the effect of RT delivered at 2Gy/#. Various formulae are used to try to convert this to a Biological Equivalent Dose when different fraction sizes are used."

Though I have not found the paper mentined by you (electronically is accessible only from 1995 onwards), but I see your point. VicM 15:35, 17 August 2006 (UTC)[reply]

Another expression I've never heard of is 'safe dose'. It is well known fact that for medium and high doses long term risks following irradiation increase linearily. For low doses there is on-going discussion as to whether beneficial or harmful effects prevail. VicM 15:21, 15 August 2006 (UTC)[reply]

"It is well known fact that for medium and high doses long term risks following irradiation increase linearily. " I don't really understand your point here. Can you be more precise, and provide references?

"For low doses there is on-going discussion as to whether beneficial or harmful effects prevail." I am not sure that this is relevant to the rest of this discussion.Jellytussle 08:07, 16 August 2006 (UTC)[reply]

I'm referring to linear no-treshold model - in short: the more radiation the bigger risk of long term effects. That's why any "safe dose" cannot be defined. According to this model even small dose of radiation can be harmful.

It is widely discussed however ie Radiat Res. 2004 Oct;162(4):447-52. - The linear no-threshold model does not hold for low-dose ionizing radiation. VicM 15:35, 17 August 2006 (UTC)[reply]

Small doses of radiation might even be beneficial, i.e. radiation hormesis. --WS 17:11, 17 August 2006 (UTC)[reply]

VicM, I think I understand now. Loose terminology is at the root of the problem. It is generally accepted that there is no "safe" dose of radiation, with respect to long term increased risk of carcinogenesis. Eric Hall, amongst others, has published widely on this. This should be distinguished from the "lifetime tolerance" discussed in the article, which pertains to tissue recovery following therapeutic doses of radiation: above a certain cumulative lifetime dose, a tissue will start to ulcerate and necrose. This is a problem when treating patients with recurrent cancer, where a second radical dose of radiotherapy cannot safely be given to a previously treated field; long term concerns about second malignancies are not usually an issue in these cases.Jellytussle 09:21, 19 August 2006 (UTC)[reply]

when?

When was radiation first used to treat cancer? HighInBC 00:51, 1 September 2006 (UTC)[reply]

Early 20th century. Can probably find the dates with a bit of a google. The first paper about radiotherapy for breast cancer was published in the BMJ or the Lancet in the early 1920s I think, but there were certainly a radiotherapy clinic in London before then. Not sure where the first radiotherapy unit was. Paris possibly.Jellytussle 07:13, 1 September 2006 (UTC)[reply]

According to this document on the ASTRO web site the first treatment began 3 weeks after Roentgen's publication of his x-ray discovery. [1] The treatment was for a breast cancer and involved 18 1-hour treatments! A very interesting paper.--Rishackie 21:12, 20 September 2006 (UTC)[reply]

I took out "therapeutic index"

I took out the mention of "therapeutic index", because I don't think it can work the way it was described.

Let's say that EBRT for a particular tumor has a therapeutic index (TI) of 2.5. Let's say that IMRT lets us safely deliver ten times the EBRT dose. With IMRT, the TI might be different -- 2.9 or 2.3 or whatever. The deliverable dose is ten times higher. That does not change the TI by a factor of ten. The TI has to compare lethal dose of a therapy with therapeutic dose of that therapy, not lethal dose of a therapy with therapeutic dose of some other therapy.

If this is wrong, please fix it, and please fix therapeutic index, and please make sure this issue stays out in the light of day.

TH 03:11, 11 October 2006 (UTC)[reply]

deleted: "maximum lifetime tolerance"

I elided the phrase "maximum lifetime tolerance" because (a) someone complained about it above and the complaint made sense to me; (b) the phrase violates the "dictum of classical physics which states that in nature everything is continuous" (Wikipedia on continuous function, giving a flower as an example); (c) I typed "maximum lifetime" radiation into http://pubmed.org and got zero hits; and (d) it doesn't make sense that one would be treated up to a "maximum lifetime" level in one's thirties, and then twenty years later the tumor comes back but the doctor says "we can't give you radiation because that would put you over your maximum lifetime tolerance".

TH 04:08, 16 October 2006 (UTC)[reply]

I think this needs to be looked into more closely. Radiation damages DNA, and that damage is passed on to future generations of cells, so it seems likely that tissues does in fact have a maximum lifetime tolerance. It's also worth noting that radiation therapy patients have their treatment fields permanently marked on their bodies with small tattoos. This serves two purposes, one of which is unrelated to the discussion, but the second of which is so that radiation oncologists can tell where a person has been treated previously in case they need more treatment in the future. If there is a limit, it might not be so well-defined that an oncologist would be able to say "you're over your limit," but evidently previous treatments are considered by oncologists when planning treatment. In any case, it was an unsourced statement, but I'd like to check it out a little more before we remove it for good. —Captaindan 06:47, 16 October 2006 (UTC)[reply]

Thanks for your interest folks. TH, try doing a pubmed search on "Radiation AND Tolerance" or somesuch. With respect to your dictum of classical physics, I don't see what that necessarily has to do with a biological system. And the idea of long-standing cumulative damage does make sense from a biological point of view. Apart from theory, it is observed in practice in radiotherapy clinics every day.

See the following:

Seminal paper on tissue tolerance to radiation:

Int J Radiat Oncol Biol Phys. 1991 May 15;21(1):109-22. Tolerance of normal tissue to therapeutic irradiation. Emami B, Lyman J et al

And the following on re-irradiation:

Semin Radiat Oncol. 2000 Jul;10(3):200-9. Tissue tolerance to reirradiation. Nieder C, Milas L, Ang KK. Department of Radiation Oncology, The University of Texas, M.D. Anderson Cancer Center, Houston, TX 77030, USA.

There are increasing requests for delivering a second course of radiation to patients who develop second primary tumors within or close to previous radiotherapy portal or late in-field recurrences. Rational treatment decisions demand rather precise knowledge on long-term recovery of occult radiation injury in various organs. This article summarizes available experimental and clinical data on the effects of reirradiation to the skin, mucosa, gut, lung, spinal cord, brain, heart, bladder, and kidney. The data reveal that, in general, acutely responding tissues recover radiation injury within a few months and, therefore, can tolerate another full course of radiation. For late toxicity endpoints, however, tissues vary considerably in their capacity to recover from occult radiation damage. The heart, bladder, and kidney do not exhibit long-term recovery at all. In contrast, the skin, mucosa, lung, and spinal cord do recover subclinical injury partially to a magnitude dependent on the organ type, size of the initial dose, and, to a lesser extent, the interval between radiation courses. The available clinical data have inspired many radiation oncologists to undertake systematic studies addressing the efficacy and toxicity of reirradiation in various clinical settings. Hopefully, systematic scoring, collection, and analysis of patient outcome will produce quantitative data useful for clinical practice. Jellytussle 11:13, 16 October 2006 (UTC)[reply]

long-term effects

Seems to me that if long-term effects are well discussed, there's no advantage to discussing the idea of "lifetime maximum". Otherwise, somebody please make the case that "lifetime maximum" is an independent phenomenon and not something that just falls out as an implication from long-term effects.

TH 20:58, 16 October 2006 (UTC)[reply]

It is worth making a distiction, since it is relevant to retreatment with radiotherapy. There is a cumulative damage to irradiated tissues. This may be completely subclinical, and may manifest itself years later only if a previously treated area is re-irradiated. It is for precisely this reason that radiotherapy doses are modified during re-treatement.

Long term side effects are arguably different, in that they manifest regardless of whether there is further radiation exposure. Long term effects include second malignancy, cardiac problems, tissue fibrosis etc.Jellytussle 08:32, 17 October 2006 (UTC)[reply]

Article items 5 and 6 (conventional radiation and then techniques)

I suggest it is a misnomer to put 'conventional' before 'external beam radiation therapy' in article section 5. My primary reason for this, is stateside the term 'conventional' refers to AP/PA treatments, commonly done for craniospinal irradiation. To put it simply, 'conventional' is not having to do with the treatment, it has to do with the treatment planning.

As such, I would suggestion article heading 6 be considered to be changed. I think a summary title of "treatment techniques." or "treatment planning techniques" would be more appropos. The reason is that the virtual simulation (typically done with CT or CT/MRI) is done to create the radiation plan, and then it is delivered via one (of many) techniques: conventional, 3D conformal (often abbreviated 3DCRT), intensity modulated radiation therapy (IMRT), and also now 4D, which is commonly referred to as respiratory gated. Also not mentioned is ultrasound based localization, commonly used for prostate cancer. I did notice that cone-beam CT was mentioned, which is cutting edge and kudos to the person who brought it up.

However, I feel that I must argue one comment. The following: There has been some concern, particularly with IMRT, about increased exposure of normal tissues to radiation and the consequent potential for secondary malignancy. Overconfidence in the accuracy of imaging may increase the chance of missing lesions that are invisible on the planning scans (and therefore not included in the treatment plan) or which may move between treatments or during a treatment (for example, due to respiration or inadequate patient immobilization). "

Articles by Studer, et al [Radiation Oncology 2006, 1:40 http://www.ro-journal.com/content/1/1/40 as well as Yao, et al [Int J Radiat Oncol Biol Phys 2005, 63(2):410-421.] have demonstrated that IMRT is proven and marginal error does not exist. The caution in using the technique, stateside, does not stem from failure of planning the margin too narrowly, but from not having the manpower (a board certified medical physicist is required for an independent chart check) as well as having the available table time (it takes up to 30 minutes to deliver a complex IMRT) and the type of treatment facility.

Also, I would respectfully argue that Image Guided Radiation Therapy (IGRT) and 4-Dimensional Radiation Therapy are different entities. It is implied that they are, in fact, the same in the statement: "This new technology is called image-guided radiation therapy (IGRT) or four-dimensional radiotherapy."

4DRT is typically refers to RT delivered over a respiratory pattern (it coincides with 4DCT). Image guided radiation therapy refers to accounting for the daily shifting from bladder filling, bowel movements, and/or weight loss. It can be redirected through cone-beam CT or ultrasound localization or fiducial markers.

Also under radiation therapy techniques, I believe radiosurgery should be mentioned. While I understand it has its own page, radiosurgery is still, fundamentally, an external beam technique that is a highly technical form of IMRT. Perhaps a mention of it should be made with the link?

I welcome your comments, critiques, and insights! Thank you Kate St. John 07:52, 6 December 2006 (UTC)[reply]

Gray correction

Corrected the term 'grays' to simply 'Gray' The plural, in radiation oncology is "Gray" and not "Grays." Similarly, it is to be capitalized upon use. Thanks! Kate St. John 14:32, 6 December 2006 (UTC)[reply]

Are you sure about that? I've seen "grays" used in literature. Also, Gray is an SI unit, and my understanding is that SI units aren't capitalized. —Captaindan 15:14, 8 December 2006 (UTC)[reply]

When we publish (UIHC in Iowa City) we use Gray and Gy. However, I just went back through the International Journal of Radiation Oncology * Biology * Physics (our journal of choice); the term Gray it is used both as 'gray' and "Gray" - but never as 'grays.' I did a search and found the NRC (http://www.nrc.gov/reading-rm/doc-collections/cfr/part020/part020-1004.html) who list it as 'gray' with the abbreviation as "Gy." So, I stand corrected, but the abbreviation is capitalized (http://www.dep.state.pa.us/dep/subject/advcoun/rpac/2003/Draft_Minutes_112002_RPAC_Mtg_Rev_3.pdf)

Thanks! Kate St. John 05:18, 11 December 2006 (UTC)[reply]

Just checking. The limited knowledge I have about this stuff comes from being a (decidedly curious) patient, so I'm certainly not an expert. —Captaindan 05:28, 13 December 2006 (UTC)[reply]

Chapter order & cumulative side effects?

I wonder why after introduction the first chapter is "Side effects"? I think it is not the most important aspect of radiation therapy.

Also, though I am rather familiar with the field of radiation protection, I have not before seen the term "cumulative side effects". I believe side effects are usually divided into acute (due to radiation damaged cells) and long term (such as fibrosis or cancer). If you want to keep cumulative side effects in the article, please explain better why so. The abstract of the given reference does not give justification, in my opinion. To me cumulative side effects just seem like a special case of acute or long term side effects. 80.222.17.246 13:50, 19 March 2007 (UTC)[reply]

No, not the same. It is usual to have subclinical tissue damage after a course of radiotherapy (long term side effects without the side effects, if you like.) Add more radiation dose on top of that at a much later date and you get worse acute and and late side effects, because the tissue threshold for radiation damage is lowered by the original treatment.Jellytussle 17:35, 19 March 2007 (UTC)[reply]