Environment and Cancer

Environment and Cancer: (page 4 of Breast Cancer Prevention)


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How does cancer start? Questions about the environment and cancer come to mind immediately. Why would one person be more likely to be diagnosed with cancer than a near neighbor, relative or family member? There is no question that genetics plays a role in answering those questions, but at the time of this writing, your genes are not something we can modify. The major modifiable factor known to promote the initiation of cancer is the presence of environmental toxins. Though the environment and cancer link connects risk to thousands of chemicals, some are quite rare; so the ones I will choose to highlight here are those to which many people are exposed in the course of everyday life, and about which we can do something to minimize risk. And many of these widespread toxins are ones that we Americans enjoy (!), so I hope you understand that the holistic medicine approach can sometimes (gently but firmly) ask us to consider changing our cherished habits.


Tobacco smoke has been a known carcinogen for decades now. A 2006 review of 40 years of research data from Japan revealed a significant number of studies in which tobacco smoke increased risk of breast cancer. Even if you are not a smoker, the environment and cancer connection comes into play with second hand smoke. Need I say more?


Alcohol is a complex subject for health. But for breast cancer prevention, studies are clear. Maybe you had not thought about alcohol consumption as an environment and cancer topic; but science demands that we look at the date regarding this culturally accepted risk. Alcohol intake increases aromatase activity (unnecessarily raising estrogen levels), which may be one reason that alcohol intake at any level seems to increase risk of breast cancer. And by the way, breast cancer is not the only malignancy which becomes more likely with alcohol intake. It is safe to say that alcohol is a cancer promoter, at least when intake is immoderate. Low to moderate alcohol intake seems to have some heart health benefits, so this is a complex topic; but for now, you just need to know that alcohol even at moderate levels of intake increases risk of breast cancer.

Polychlorinated biphenyls (PCB’s) are industrial chemicals which have been widely used in plastics, paints, and adhesives. These do not break down easily in the environment, enter the food chain and are then stored in the fat tissue of animals. The presence of PCB’s is a known risk factor for breast cancer. Limiting consumption of PCB’s can be accomplished by being aware of their sources in our food supply, and making wise choices. One of the easiest is to know which fish are likely to be contaminated with PCB’s, and choose other healthy fish. This information is publically available, through such online resources as the Oceans Alive web site. Farm raised salmon is currently one of the fish types known to be an unsafe source of PCB’s, and I suggest that for breast cancer prevention that you avoid those fish and consume only wild Alaskan salmon instead.

Just like you may not have thought of alcohol as an environment and cancer exposure, we have to look at another common food item which has toxic risks for cancer. This one, just like a beer on a hot summer afternoon, is as American as apple pie: the backyard grill. A common cancer causing chemical exposure is the presence of heterocyclic amines and polycyclic aromatic hydrocarbons formed from cooking meat at high temperatures. This is especially true of grilling meat, chicken or fish, if it results in any charring. In fact, consumption of well done, fried, or barbecued meat is now known to be a breast cancer risk. My advice on meats: eat less, and when you do eat it, enjoy your steak cooked medium at most. Slow cooking at lower heat may be a better choice for breast cancer prevention.

Pesticides and plastics also deserve some discussion. With regard to breast cancer, the pertinent problem is that many chemical pesticides used in farms and gardens act as xenoestrogens. A xenoestrogen is a compound which has no natural place in human life, but which by chance (very bad luck) interacts with human tissue and triggers a response which would normally be reserved for a human hormone. So pesticides act as xenoestrogens when they bind to estrogen receptors in the body (specifically the breast) and cause those receptors to become active as if there were higher levels of estrogen circulating. Similar compounds also enter the body through exposure to some plastics, such as when foods are placed in a microwave oven in a plastic container and the plastic compounds which act like estrogens leach into the food. As you might have guessed by now, for optimal breast cancer prevention, I am suggesting that you minimize pesticide exposure by choosing organically grown produce whenever possible and by not cooking or storing food (or water) in plastic containers. For information on how to choose organic most efficiently by avoiding only the most contaminated foods on the market, see the internet resource of the Environmental Working Group.This excellent web resource can help you cut the environment and cancer connection for you personally without breaking the food budget. It’s estimated you can decrease your pesticide burden in foods by 90% simply by avoiding the top 10 most contaminated and only buying organic for those ten.

Here’s an area where environment and cancer are connected to us indirectly through the environmental treatment of another animal. The role of hormones used in dairy and meat production deserves a cautionary note. The treatment of dairy cows with rBGH (recombinant bovine growth hormone) is a controversial topic. (It is also called rBST, recombinant bovine somatotropin). While I know of no studies linking such milk to human cancers, breast or otherwise, I believe there is reason for caution and avoidance until we prove (if ever) that there is not a problem here. We know that the rBGH/rBST is not actively excreted in the cow’s milk, and so you as the consumer are not put at risk by the rBGH/rBST itself. But that same milk does have higher levels of another hormone in it, called insulin-like growth factor, or IGF-1. Good science has shown that IGF-1 is a tumor growth promoter, so any set of mutated cells that is growing out of control tends to multiply faster in the presence of IGF-1. For something as important as breast cancer prevention, I believe this is reason enough to insist on consuming only dairy products which have not come from cows treated with rBGH/rBST. Read the labels in the store: if it does not say “certified organic” or “rBGH/rBST free” there is a very good chance those cows were exposed and that milk is unsafe in my opinion. So while the science on this topic is not conclusive about any increased cancer risk, I still believe the precautionary principle applies for breast cancer prevention as much as for any other health issue: do not knowingly expose yourself to a substance about which there is reasonable concern when you have an alternative.

I know this is a complex topic, for which science is still developing. But at the very least, we know there is an environment and cancer connection, and that connection may be especially important for breast cancer, so please consider these precautions. 

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