Genetics, environment, and cancer

A friend of mine just posted this blog post by Dr. Jane Philpott about cancer prevention via diet, including lots of detailed information about the mechanisms by which cancer develops.  I noticed that although she introduces her topic by discussing Angelina Jolie's decision to get a double mastectomy in response to having a breast cancer gene mutation, she discusses the effect of the environment on non-mutated genes to change them so that they allow or cause the growth of cancer.  Thus, I wrote the following response:

Informative article. Thanks for sharing. This is definitely a big part of why I lead a healthy lifestyle. (My doctors always look at my health history and say, "Your choices are great but your genes are rotten." Yes, I know, thanks.)

People have often argued with me on my healthy lifestyle choices, saying, "but you can't avoid xyz environmental problems so you're never going to win." Air pollution, cross-contamination of even organic food, cell phone networks everywhere, computer use... it goes on, all the things we can *not* control.

I would argue that the fact that they're right - I can't control everything - is more reason I should control what I can. Some people will choose to control what they can by opting for prophylactic mastectomy.

I have seriously considered and continue to consider getting tested. The BRCA gene mutation associated with Jewish women born after 1920 has a high fatality rate. The first Jewish woman born after 1920 in my family = me. The last Jewish woman in my family before me was born in 1906 and the next was born in 2003. I have no basis for comparison, no family history to use to decide whether there might be this gene in my family. My life experience with breast cancer is learning how much it sucks when someone dies too young of it - my two grandmas on my mom's side (both non-Jewish, one related by blood, one by marriage) died at 61 before I was born and at 51 when I was 11.

I understand that I have half the chance of having the Jewish version of the BRCA gene because I'm only half Jewish. I'm still waiting for someone to tell my Tay-Sachs gene about that.

The decision to get tested and to take action if positive also may hinge on this: "Unlike mutations, DNA methylation and histone modifications are reversible." Unlike mutations. So when someone is faced with an actual mutation, what do our food choices do for that? I saw lots of evidence in this article for preventing gene changes away from healthy genes to genes that allow cancer to grow, but not a lot of evidence to support that our choices will help our DNA shift away from inherited harmful mutations. I'd love to see any studies on that.