Cancer: bad luck or punishment?

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Sangoma
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Cancer: bad luck or punishment?

Post by Sangoma » Sat Sep 16, 2017 1:54 am

It looks like most of us missed an interesting argument that has been unfolding in the last couple of years. In 2015 Tomasetti and friends published an article that came to the conclusion that 2/3 of cancers are caused by bad luck. In short, they found very strong correlation between the rate of division of cells in the tissue and the incidence of cancer in that tissue. When this finding was combined with epidemiological data it followed that about 70% of all cancers are due to stochastic processes of mutation, i.e. bad luck.

Full text for the interested: Variation in cancer risk among tissues can be explained by the number of stem cell divisions

Most responses (in fact, all of them) to this article have been negative, but not very strong in terms of a scientific argument.

Lo and behold, a year later another author, Song Wu, comes up with another estimation. This time about 10-30% of cancer is caused by chance and in 70% of cases are caused by environmental factors: Substantial contribution of extrinsic risk factors to cancer development

Finally, there is another article that puts things into perspective: Cancer: Bad Luck or Punishment? by Anatoly Lichtenstein, a Russian researcher. His conclusion:
Tomasetti and Vogelstein [2] attribute approximately 70% of the variation in cancer incidence to inherent cel􏰀 lular processes, while Wu et al. [12], by contrast, attribute approximately the same fraction to extrinsic factors. This “tug􏰀of􏰀war” is seen as being abstract to some extent. As noted by others [4, 5, 8, 9, 41], the ratio of intrinsic and extrinsic factors varies depending on the living conditions of the particular population. In fact, a population with a high living standard (and therefore having a long lifespan and good environment, food and hygiene) will be charac􏰀terized by a high lifetime risk of cancer and a predomi􏰀nant contribution of endogenous factors to morbidity. In contrast, a population with a low living standard (and, consequently, a shorter lifespan and an excess of adverse external factors) would be characterized by a lower life􏰀 time risk of cancer and, in this case, a greater contribu􏰀 tion of exogenous factors to cancer incidence. Insofar as the entire controversy is based on statistics derived from a country with a high living standard (the US), regarding this situation it is difficult not to agree that “cancer is vir􏰀 tually inevitable in complex, long􏰀lived, multicellular organisms; somatic mutations inevitably accumulate with time and, aided by selection at the tissue level, can erode the cancer􏰀suppressive mechanisms” [25].

Thus, the answer to the question posed in the title of the article is that cancer can be, depending on circum􏰀stances, both bad luck (in favorable life conditions) and punishment (in adverse life conditions). Accordingly, the role of cancer prevention efforts will vary considerably in these circumstances.
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climber511
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Re: Cancer: bad luck or punishment?

Post by climber511 » Sat Sep 16, 2017 3:13 am

100% of cancers are caused by - wait for it ..............................cancer.

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Sangoma
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Re: Cancer: bad luck or punishment?

Post by Sangoma » Sat Sep 16, 2017 3:22 am

To crown the debate, earlier this year Tomasetti group came up with the new study. This time they studied the relationship between the number of normal stem cell divisions and the risk of 17 cancer types in 69 countries throughout the world. "The data revealed a strong correlation (median = 0.80) between cancer incidence and normal stem cell divisions in all countries, regardless of their environment (emphasis mine).

Stem cell divisions, somatic mutations, cancer etiology, and cancer prevention
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