Cancer: It’s Not All in the Genes!

If you consider breast cancer unavoidable since your mother and sister both experienced it, you’re in for a pleasant surprise.

Breakthrough research published in the July 13, 2000 issue of the New England Journal of Medicine sheds new light on a rather worrisome, complex subject. Dr. Paul Lichtenstein and colleagues at the Karolinska Institute in Stockholm reported key findings that signal good and bad news in our struggle to discover a cure for cancer.

Let’s deal with the bad news first. Despite recent advances in elucidating the human genome, it now appears that genetic manipulation will not put a halt to cancer. While genes appear to account for 42 percent of the risk for prostate cancer, 35 percent for colorectal cancer and 27 percent for breast cancer, the remainder of the risk is multifaceted. Of great importance is the fact that the majority of the risk is attributable to lifestyle choices like smoking, diet, alcohol and activity, as well as chemical/environmental exposure, viral infections and random genetic mutations.

On the positive side, it is important to review your odds for developing cancer based upon family history alone. Let?s begin by considering that if your brother has prostate cancer, you do not carry a 42 percent risk of developing it. Based upon Lichtenstein’s survey of close to 45,000 sets of twins in Sweden, Denmark and Finland, even the identical twin of someone with prostate, breast, or colorectal cancer has only an 11-18 percent chance of developing the same cancer by age 75. For fraternal, or non-identical twins, the risk was only 3-9 percent.

While Lichtenstein’s findings were statistically valid for prostate, colorectal and breast cancer, limited heritability was also noted for leukemia and cancer of the stomach, lung, pancreas, ovary and bladder.

The statistics presented above are critical to understanding that even in the presence of the same genetic makeup (identical twins), the risk of developing the same type of cancer was surprisingly low. The findings are best summed up by Dr. Robert Hoover of the National Cancer Institute who clearly stated, “Someone with an identical set of genes has a much greater chance of not developing cancer than of developing it.”

I personally find these data illuminating from multiple perspectives. The most obvious is that genetics accounts for a lesser role than typically expected in the development of cancer. The second and even more important insight is the fact that cancer does seem to be rather prevalent in certain families, despite these seemingly low probabilities. This fact brings to light the possibility that lifestyles adopted by families might play a more important role than previously noted. Consider the following example:

A mother and her two daughters in their thirties have breast cancer. While one might initially assume that genetics was the underlying cause of the disease in all three women, is it not possible that additional factors shared by the mother and daughters could be at least partially responsible? Is it within the realm of possibility that family lifestyle habits shared by the women including alcohol consumption, smoking, diet, lack of exercise and being overweight are significant contributors?

From an objective perspective, while it is impossible to know the precise cause of cancer in most individuals, one must assume that the causality of the disease is multifaceted. Based upon this research coupled with the findings of the American Institute of Cancer Research (AICR), it is well-established that up to 70% of cancer is preventable with avoidance of tobacco, limited alcohol consumption and a proper diet.

With this knowledge in mind, how can we optimize our odds for preventing cancer even in the context of having a positive family history?

The answer lies in the fact that there are some things we can control and others we cannot. Clearly, early detection is key and appropriate checkups at prescribed intervals are essential. Following the AICR’s guidelines can substantially improve one?s odds. Exercise is another proven factor related to diminished cancer risk.

The bottom line is straightforward. Family history isn’t the only thing that matters and cancer isn’t always preventable. Yet the way you choose to live your life impacts your future. Ultimately, it’s important to realize the odds are truly in your favor–Mind Over Matter!

© 2000 Barry Bittman,
MD all rights reserved

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Written by Barry Bittman MD

Explore Wellness in 2021