Most common cancers caused by radiation exposure?

[ElliotSmith]

TL;DR

What are the most common types of cancer caused by exposure to excessive amounts of radiation?

What are the most common types of cancer caused by exposure to excessive amounts of radiation?

 

[russ_watters]

Just go through the list of common types of cancer and identify ones caused at least in part by radiation. The top one is skin cancer by a factor of 10 over lung cancer. Skin cancer is exclusively caused by radiation. Lung cancer partly by radiation.

 

[ElliotSmith]

Just go through the list of common types of cancer and identify ones caused at least in part by radiation. The top one is skin cancer by a factor of 10 over lung cancer. Skin cancer is exclusively caused by radiation. Lung cancer partly by radiation.

What about Leukemia and Thyroid cancer?

 

[russ_watters]

What about Leukemia and Thyroid cancer?

Did you google them as I suggested? What did the sources you found say?

 

[artis]

@ElliotSmith You should also differentiate between types of radiation and types of cancer.
Not all types of radiation cause all kinds of cancer.

For example , it is highly unlikely you will get lung cancer from too much exposure to sunlight, but it is much more likely you can get skin cancer from that.
Smokers get more lung cancer on the other hand and do you know why ?

 

[Rive]

What about Leukemia and Thyroid cancer?

Maybe you should re-specify the initial question. As it was hinted before, 'radiation exposure' includes all kinds of radiation: UV from sunlight definitely included. And, indeed, within this context (radiation in general) the most frequent danger coming from sunbathing.

Radiation as radioactivity is a slightly different issue. Alpha and Beta as external radiation has limited penetration, usually only the skin is affected. Gamma affects the whole body, kind of a diffuse way - so no specific cancer type for this, it affects the general risk instead.
Effective neutron radiation is really rare and usually related to a specific type of accident (criticality accidents). So rare that I don't think that any specific type of cancer is associated so far.

Leukemia and thyroid cancer specific to ingested radioactive materials (radioactive Strontium and Iodine and some more) and not to external radiation.

 

[Ygggdrasil]

We have a natural experiment performed by the US government to study the issue: https://pubmed.ncbi.nlm.nih.gov/20843820/

 

[gleem]

The proper term for radiation as is normally used is ionizing radiation which is considered to be radiation with an energy greater than 10 eV (FCC) which is the extreme limit of UVC. However, UVC is absorbed in the upper atmosphere so is not a contributing factor for skin cancer.

Leukemia and thyroid cancer specific to ingested radioactive materials (radioactive Strontium and Iodine and some more) and not to external radiation.

Not really. Although there are radioisotopes that are organ-specific like the Beta emitters Sr-90 for bone and I-131 for the thyroid that can cause cancer external radiation gray for gray is just as potent as the Beta emitters. About 15% of radiogenic cancers in atomic bomb survivors are leukemia. A study of patients irradiated with x-rays to treat an inflammatory spine condition known as ankylosing spondylitis appeared to develop leukemia at a rate of 1-2 case/million persons/0.01Gy among other cancers.

In the early years of radiation use, skin cancer of the hands was common. Radiologists and physicists would handle isotopes or adust unshielded X-ray tubes with their bare hands. Leukemia was also elevated in these groups. Radiologists continued to show elevated leukemia occurrence up until the early 50's.

Atomic bomb survivors represent the largest exposed population that continues to be studied for the carcinogenic effects of ionizing radiation. Of the 100,000 or so survivors in the study, about 950 persons so far developed cancer attributable to radiation. exposure. Common types observed include oral cavity, esophagus, stomach, colon, liver, lung, nonmelanocytic skin, female breast, ovary, urinary bladder, brain/central nervous system, and thyroid.

 

[artis]

central nervous system

I actually never knew that there can also be such a thing as nerve cancer. Every day you learn I guess.
Thanks @gleem

 

[S Holtom]

I think this is one of those questions that seems straightforward but may not actually be answerable.

Because firstly we don't normally know the exact cause of an incidence of cancer. Often there is some combination of radiation exposure (who among us can avoid solar and cosmic radiation?), other mutagens and susceptibility of certain tissues. And often we just don't know. What causes bowel cancer?

Also we might need to clarify what we mean by "most common".

Let's say there's Cancer A, which causes 1000 deaths a year, about 30% of which are thought to be caused by radiation exposure.
And there's cancer B, which is 100% caused by radiation and exposure and causes 400 deaths a year. Which of these is most common?

 

[gleem]

The only cancers that have a radiation exposure link are acute and chronic myeloid leukemia. For other cancers, the percentage that could be from radiation exposure is typically quite low. It is estimated that about 1% of cancers are due to incidental radiation exposure including background and medical x-rays. The only way to identify which cancers are caused by radiation is to compare an exposed population to an unexposed population of similar characteristics. For atomic bomb survivors, the excess of cancers is 11%. The results of the study of these persons are shown in the graph below from https://www.nap.edu/read/11340/chapter/8#144

Excess relative risk is the rate of disease in an exposed population divided by the rate of disease in an unexposed population, minus 1.0. For the graph above it is for a dose of 1 Sv (RBE = 10). Cancers of the breast, thyroid, bladder nonmelanoma skin and lung seem significantly elevated. Note the size of the uncertainties

 

[hutchphd]

Alpha and Beta as external radiation has limited penetration, usually only the skin is affected.

Of course often that "skin" is in the interior of your lung

Because firstly we don't normally know the exact cause of an incidence of cancer.

Statistical methods applied to populations allow firm conclusions to be drawn about populations however. This makes it difficult to successfully sue Kerr-McGee or the builders of Windscale for damages but Uncle Fred will still be dead.

 

[S Holtom]

Statistical methods applied to populations allow firm conclusions to be drawn about populations however.

That will depend on what data we have to start with. I think in the case of most cancers we would not be able to rank the various mutagens.
When there's a rare genetic disposition or extreme exposure, it's often clear-cut enough to say "so and so gene doubles your risk of breast cancer" or "workers in this radium factory are 10 times more likely to get esophageal cancer".
But the much more typical cases of low-level exposure to multiple carcinogens, plus genotypes that are common in the population and might increase risk by a much slimmer amount? Much harder to draw firm conclusions. And indeed, impossible to have certainty as there are always potential known and unknown unknowns.

 

[Laroxe]

I think you have to start by forgetting the notion that cancer is a specific discrete disease, we have more than 200 cell types all of which can develop into cancers, but these cancers can all be very different. We can start with the notion that cancers tend to start with some form of genetic damage, most damage tends to occur at mitosis but we have elaborate checking systems that generally destroy these cells. However, we do see a lot of cancers arising in tissues with high rates of cell division, many of these have increased exposure to the external environment so may be prone to more damage or chemicals, some of which will be carcinogens which also damage DNA damage. We even have the ability to produce our own carcinogens as by products of metabolism, being alive is carcinogenic.

To develop into cancers, cells have to have a number of very specific changes and also avoid the attention of our immune system. During the process of living we are exposed to a huge number of forces capable of initiating these changes and over time these changes accumulate in certain cell lines. This is why cancer are overwhelmingly a disease of old age, it's very difficult if not impossible to quantify the levels of risk from individual risk factors, because people are very different and the way people are exposed to various risk factors is so variable. The cancers seen in children tend to be very different and often have different risk factors, which we won't address in this.

Radiation exposure, as a risk factor, apart from some specific forms of exposure from radioisotopes, is particularly confusing. Following the use of atomic weapons, the predicted increases never really materialised, there were some increased rates often of specific cancers and these occurred over a much longer timeframe, it seems the timing of the exposure and the duration were important variables. The effects of exposure on DNA were well known, the body's ability to recover from these effects were and are poorly understood.
As cancers develop, the cells within them can follow very different developmental pathways, the cells become increasingly different from the host and in fact to each other, as new abilities develop which can increase the damage it causes. there can be considerable costs to the abnormal cells. One of these costs is in the ability of at least some of the cells to repair radiation induced damage, we can use this information and the awareness of the importance of cells in mitosis to use radiation in ways that cause more damage to cancer cells than the surrounding tissue.

In normal circumstances, for the majority of people the risks from radiation are rather predictable and so they are manageable. Don't live by a power station, coal or nuclear, don't build your house on granite and cellars are a definite no, no and avoid nuclear explosions, especially that big one in the sky. In itself, radiation is invisible and has been demonised by vested interests, but it isn't really that important. Its perfectly reasonable to blame it on the fates or lady luck, otherwise you start to blame it on yourself, there is currently no great difference in the quality of evidence for either.

 

[S Holtom]

The effects of exposure on DNA were well known, the body's ability to recover from these effects were and are poorly understood.

Yep, and as a further addendum to this (this is a bit of a hijack, but I think it will be of interest):

I work in radiotherapy. That is, using radiation to treat cancer (and other things, but mostly cancer).

Most people are terrified by the very idea of being treated with radiation, but in fact it is the gold standard for many cancers; beams are focused very precisely on the tumors themselves, meaning side effects are so minimal that many patients can be treated as outpatients.

Conventional radiotherapy involves fractionation: that is, giving a small radiation dose over several sessions instead of all in one go. The advantage of this is that any healthy tissue that has received radiation dose can repair its DNA, whereas cancers generally can't (obviously if cancerous cells completely repaired their DNA they would not be cancer any more. However, some forms of cancer are unfortunately able to repair their DNA to a limited degree while staying pathological).

In recent years however, there has been a shift, as now flash therapy is now being incorporated into many treatments -- this is where a large dose is delivered very quickly; in a fraction of a second. For reasons that are still unclear this leads to even better results in terms of the treatment effectiveness and minimizing damage to the healthy tissue. Research is ongoing, but in the meantime of course it makes sense to use this therapy even if we don't fully understand why it works.

Anyway, my point was just to agree about how much we still need to understand about the effect of radiation on cells.

Oh and in the interest of completeness I should mention that flash therapy and fractionation are not necessarily opposites; you can have a fractionated treatment where each fraction is given in less than a second. There is a robust debate right now on what is the ideal way to deliver doses.

 

[gleem]

In recent years however, there has been a shift, as now flash therapy is now being incorporated into many treatments -- this is where a large dose is delivered very quickly; in a fraction of a second. For reasons that are still unclear this leads to even better results in terms of the treatment effectiveness and minimizing damage to the healthy tissue. Research is ongoing, but in the meantime of course it makes sense to use this therapy even if we don't fully understand why it works.

Please read this very recent review article on Flash Therapy.

https://www.frontiersin.org/articles/10.3389/fonc.2021.644400/full#f2

from the article

Furthermore, before FLASH-RT is used clinically, two problems need to be solved. First, because of the differences between animal models and humans, the FLASH effect should be confirmed in cancer patients. Acute and late toxicity in different organs should be monitored. Second, because FLASH-RT can be completed in a single sitting, the definitive irradiation dose for different cancers needs to be redefined. Radiation oncologists should rebalance the effect of irradiation and healthy tissue toxicity and then define the radical irradiation dose. This may require the treatment of many cancer patients and a long time before this is satisfactorily defined. It may take many years before FLASH-RT becomes a mainstay radiotherapy technology in clinical applications.

 

[S Holtom]

Thanks for that, but I think it's going to get us too much into the weeds.

For the purpose of this thread, I take back the statement that flash necessarily is the more effective / safe treatment. Yes that may still be debated.
And for the purpose of this thread, my main point that we are still trying to better understand the short and long-term effect of radiation dose to healthy cells seems reinforced by that article.

 

[berkeman]

I can always break off a discussion into a different thread if appropriate. I think the OP discussion and this new discussion are both valuable. Let me know if you want to fork this thread, and thank you both.

 

[gleem]

While Flash Radiotherapy is of interest medically/radiobiologically the real issue for the OP is chronic radiation exposure and its relation to the incidence of cancer. The point that @S Holtom brought up WRT fractionation is important. It has been known for over a century that breaking up a radiation treatment into smaller doses spread out over time had a much smaller effect than a single large dose. Like fractionation, protraction of the dose over a long period of time has a similar effect. This effect has been not been taken into consideration of estimates of cancer rates per unit dose for radiation safety purposes which suggests that cancer incidence due to radiation exposure may be considerably overestimated.