Contradicting Previous Study, Cancer Risk Has Strong Environmental Component (washingtonpost.com)

The Real Dr John writes: A new study published in the journal Nature provides evidence that intrinsic risk factors contribute only modestly (less than ~10–30% of lifetime risk) to cancer development in humans (abstract). An earlier study had found that the more stem-cell divisions that occurred in a given tissue over a lifetime, the more likely it was to become cancerous. They said that though some cancers clearly had strong outside links – such as liver cancers caused by hepatitis C or lung cancer resulting from smoking – there were others for which the variation was explained mainly by defects in stem-cell division. The new research shows that the correlation between stem-cell division and cancer risk does not distinguish between the effects of internal (genetic) and external (environmental) factors such as chemical toxicity and radiation. They also found that the rates of endogenous mutation accumulation by internal processes are not sufficient to account for the observed cancer risks. The authors conclude that cancer risk is heavily influenced by environmental factors.

Comments

Three part cancer risk

[Yergle143]

I work in the Cancer field here's my take home take.
The Individual probability for Cancer risk is in three parts.
1/3 Genetics: Beyond your control, a complex interplay of genes can lead to cancer.
1/3: Environment: Within your control there is a known influence of diet, chemicals, radiation, pollution etc. Lifestyle in other words can impact this component.
1/3 Random Chance: Billions of cell divisions occur to in our lives. The protein machinery that makes this happen has incredible fidelity but mistakes inevitably occur and this DNA damage can cause cancer, usually later in life. There is no lifestyle choice that an individual can make to prevent this damage from occurring. I would also lump into random chance the random inflammatory insults that occur over a lifetime -- a cold at a young age that damaged a subset of lung tissue that mutated the p53 gene giving rise to etc.
The linked paper/story reveals a raging controversy between constituencies for each part of the cancer risk pie. The losers are the patients/public who are misled by either an indifference to risk aversion or a single minded overestimate of the benefits of lifestyle. Its all three.