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

Interesting.

[Anonymous Coward]

My mom died of breast cancer. She never really smoke or drank, and ate fairly healthy, at least by the standards of the day. However for a lot of years we lived next door to farmfields that they sprayed with pesticides from airplanes, and it got to the point where we stopped drinking water from our well.

Makes me wonder if that could be a connection.

Re:Interesting.

[dwywit]

I've told my daughter that hairdressing is not a career option. Have you smelled some of the "product" they use? It becomes clearer with a little research - coaltar or benzine-derivative hair dyes. Doing your own hair once in a while - fine. Exposing yourself daily to that stuff *has* to have an effect.

Re:Interesting.

[RobertM1968]

Wanna know the best protection against breast cancer? Popping out a new kid every year.

Did that line work?

Re:Interesting.

[JoeMerchant]

The point where you probably should have stopped drinking from your well was probably a few months after the first pesticide use started.

In Florida, there's a huge difference between shallow wells and the deep aquifers. In the 1950s, when my father was growing up, all you had to do was dig a hole 12" deep and most days there would be clean drinking water there. When I was growing up in the 1970s, the shallow water table had dropped from just below the surface to 10 to 20' down, but you wouldn't drink shallow water anymore because it was all so polluted by then. If you were going to drink well water, you wanted to taste the sulfur in it to be sure it was coming from the deep (160'+) aquifer.

Now, there's talk of "recharging" the deep aquifers with river water - what could possibly go wrong with that scheme?

No shit

[penguinoid]

Everyone who knew anything about the subject knew that cancer has a strong environmental component. What the previous study had done was merely verify something lots of people already expected, namely that cell division (and especially stem cell division) gave you a risk of cancer due to inherent mutation rates.

Environmental mean...?

[PuckSR]

Can't wait to see all the anecdotes about chemicals that cause cancer.

This study is not stating that if we all lived in a paleo-era utopia that we wouldn't get any cancer.
It is simply stating that cancer isn't pre-cooked into our lives. If we lived in a perfectly sterile environment and did not expose ourselves to any energy of any kind, we would be very unlikely to develop cancer. We would just die due to a vitamin D deficiency and a lack of human contact.

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.
 

Re:Three part cancer risk

[tlhIngan]

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.

This is also beneficial because it's how evolution happens - random genetic mutations potentially give us traits that make us more (or less) successful at surviving.

The problem is the cell has lots of mechanisms to detect copy errors - there are proofreaders to ensure the right bases are joined together, there are cell division mechanisms that detect abnormalities and cause the cell to commit suicide, etc. And they're remarkably effective, but not 100%. That's good in that random genetic mutations are necessary for life, but bad in that sometimes the mechanisms fail to detect a cancer condition and cause cell suicide. (It's a problem of large numbers - even if it was 99.99999% effective, enough cells divide all the time that the failure of detecting the mutation means you will get lots of them in the end.

Random errors happen. But they aren't all bad, and they happen remarkably often due to the law of large numbers. Not every mutation will turn into cancer, after all.