Apr
29
2017

Cancer By Chance

A new theory talks about cancer by chance. In other words, it likely is mostly bad luck when cancer develops. Mathematician Cristian Tomasetti and cancer geneticist Bert Vogelstein of Johns Hopkins University in Baltimore, Maryland developed a new model of cancer development. They found that stem cells in different organ systems divide at different rates. The faster they go through cycles of cell divisions, the higher the chances of a mutation. The mutations happen in the genetic material and can lead to cancer. Dr. Vogelstein applied this model to 32 different cancer types and found the following.

  • 66% of cancers: cancer-promoting mutations develop by chance during cell division in various organs
  • 29% of cancers are due to environmental causes
  • 5% of cancers are inherited

Stem cells in organs can turn into cancer by chance

Key to the new theory of “cancer by chance” is that cancer likely is developing from stem cells in different organs. Different stem cells have different rates of stem cell divisions.

In pancreatic cancer they found that 5% were inherited, 18% were from environmental factors (smoking) and 77% came from chance mutations. This data was derived from the Cancer Research UK database.

For prostate cancer the rate of spontaneous mutations is 95%. When all of the cancers are looked at about 1/3 of cancers are due to either environmental or inherited factors, but 2/3 of all cancers are due to random mutations (“bad luck mutations”). They pointed out this fact in their first publication.

With the second publication, as mentioned in the beginning, Vogelstein and Tomasetti concentrated on 17 common cancers in 69 countries. They searched 423 international cancer databases. Again they found that the more stem cells divided in an organ, the more random mutations occurred. This caused cancers in that organ.

Here are a few examples for lifetime stem cell divisions:

  • Colon: 6,000 cell divisions in stem cells of the colon
  • Breast: 300 cell divisions in breast stem cells
  • Lung: only 6 cell divisions in lung stem cells

Colon cancer is very common because of the high stem cell division rate. But they also looked at environmental factors. For instance, lung cancer is rare in non-smokers because stem cells in lungs divide slowly. However, the carcinogens from cigarette smoke add a huge environmental risk. The end result: there is more lung cancer in smokers. Vogelstein said that with every stem cell division there is the creation of three new cell mutations because the body has a “poor copying machine”. During meiosis DNA breaks can occur that lead to mutations. Once they occurred, they continue to get copied.

Environmental factors versus cancer by chance

In the first paper the medical community was critical about how the authors had overemphasized that two third of cancer is caused randomly. So in the second paper Vogelstein and Tomasetti mentioned quite a bit how a change of the environment can change the final outcome of developing cancer.

This is also reflected in this summary from the CNN.

They mentioned that one mutation is not enough to cause cancer. You need three or four such mutations. As we get older there is a higher likelihood that we accumulate this number of mutations, and cancer can develop. But if we exercise, stop smoking and avoid red meat, this can contribute to a much healthier environment in the dividing stem cells. In this case we may not accumulate enough stem cell mutations in our lifetime to come down with cancer.

There is a problem with prostate cancer as indicated in this German summary of Vogelstein and Tomasetti’s work.

Japanese men have an extremely low rate of prostate cancer, namely 1/25th of the rate in the US. When Japanese men immigrate to the US, it does not take long before their risk is the same as that of US men. This is a classical case of the importance of environmental factors in cancer causation. Song Wu has pointed out in a publication in Nature that in his opinion Vogelstein and Tomasetti did not pay enough attention to extrinsic (environmental) factors in the causation of cancers.

This could explain the prostate cancer conundrum just mentioned. There may be more xenoestrogens in the environment in the US when compared to Japan, and this may have caused the additional prostate cancers when Japanese men moved to the US. Xenoestrogens are estrogen-like hormones in the environment, which can cause prostate cancer.

Prevention undermines “cancer by chance”

The role of prevention is likely larger than previously estimated. Now that we know that on average 2/3 of all cancers are due to chance mutations, it is important to realize that prevention and early detection play an enormous role.

  1. Most cancers can only be cured in stage 1 and stage 2 out of 4 stages. And this is only the case when the mutated stem cells are removed along with the clone of cancer cells.
  2. In terms of reducing the risk for lung cancer this means to stop smoking.
  3. With colon cancer it means having regular colonoscopies where the suspicious polyps are removed.
  4. For prostate cancer it means to do a mapping biopsy and to do cryoablation therapy, which has a prostate cancer vaccination effect as well.
  5. Not all cancers can be diagnosed early. Pancreatic cancer is such a difficult to diagnose cancer. But screening methods have been developed that are more sensitive and very specific such as the Oncoblot test.  With this test even cancer of the pancreas can be diagnosed years before it would be clinically detectable.
  1. We do know that chronic inflammation can lead to cancer. It makes sense therefore to start with an anti-inflammatory diet like the Mediterranean diet. Fish oil is also anti-inflammatory.
  2. Add to this regular exercise, as we know it reduces the risk for cancer development and strengthens your heart and lungs.
  3. Vitamin D3 can reduce cancer risks in both males and females. When vitamin D3 was given and blood 25-hydroxyvitamin D levels were above 40 ng/ml, the breast cancer rate was reduced by 71% compared to a low vitamin D3 group. Similarly in men the prostate cancer rate dropped by 71% with vitamin D3 supplementation.  There is more good news with vitamin D3. You can read about it in the link.
Cancer By Chance

Cancer By Chance

Conclusion

The causes of cancer have always been by chance, by environmental exposure and by inheritance. In recent years more detail about this has come to the forefront. Now we know that the majority of cancers develop by chance, but this does not mean we should sit back and do nothing. The PAP test with early diagnosis of cancer of the cervix and early treatment has almost eradicated this cancer. HPV vaccinations have added to the armamentarium. Colonoscopies have reduced the incidence of colon cancer, but only through screening at regular intervals. The PSA test has enabled men to check for prostate cancer, and early treatment for this is quite successful. More is known about cancer prevention through supplements and lifestyle.

Nature is cruel and wants to knock us off, as we get older. The only alternative we have is to fight back as follows: reducing environmental causes, increasing preventative steps and going for early treatment, when cancer is diagnosed.

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About Ray Schilling

Dr. Ray Schilling born in Tübingen, Germany and Graduated from Eberhard-Karls-University Medical School, Tuebingen in 1971. Once Post-doctoral cancer research position holder at the Ontario Cancer Institute in Toronto, is now a member of the American Academy of Anti-Aging Medicine (A4M).

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