Sunday, June 13, 2010

Genetics and cancer prevention

The Times today reports that the genome (http://nyti.ms/9CqHdl) has deepened understanding of human genetics and opened up the potential for new approaches to treatment of disease. The potential pay off has not yet arrived, however. As the Times story notes, a family history of disease provides a good summary of risk, and also identifies those for whom prevention may offer substantial benefits.

In the same decade that we invested heavily in this scientific enterprise, (3 billion dollars in the Human Genome Project), we also have made progress understanding prevention of chronic diseases. For example, additional insights have been gained on the role of exercise and weight loss in reducing risk of breast cancer (see Maruti et al, 2008 - JNCI - and my presentation http://bit.ly/d2SY2s). Studies show that higher levels of activity from onset of menstrual periods in young girls through to their 20s and 30s, results in prevention of one quarter of premenopausal breast cancer. This is most important since our treatment approaches for premenopausal disease have not progressed as rapidly as for postmenopausal breast cancer. In addition to exercise, we see growing evidence that high fiber diet and higher soy intake in childhood and adolescence reduces risk of breast cancer throughout life.

We should not sit in awe waiting for genome sciences to produce a miracle cure but we should act on what is already known. The Susan G. Komen for the cure, for example, spent 3% of its funds on prevention research between 1982 and 1996, and in 2008 to 2009 they spent 7 percent of the research portfolio on prevention. Clearly like other organizations funding research and prevention of chronic disease, they too await or hope for a miracle cure.

The benefits of healthy childhood and adolescence are not limited to breast cancer prevention. Avoiding excess weight gain during childhood and adolescence can prevent the onset of diabetes. Healthy diet and exercise have numerous pay-offs through the adult years but prevention begins in childhood.
Reorienting our priorities to prevention could substantially reduce the burden of cancer, heart disease, diabetes, and other chronic conditions. Growing attention to salt in the diet points has identified population-wide strategies that can reduce blood pressure. We need to engage as a society to make the changes that will reduce the burden of chronic disease and hence save many future expenditures that are driven by the diseases caused by our lifestyle including lack of exercise, obesity, and poor diet.

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