Exercise and Breast Cancer Risk

It is now known that physical activity reduces the risk of breast cancer but the exact relationship between “dose” and timing of exercise  - particularly in relation to menopause – is less well defined.   A new study from the Department of Epidemiology at the University of North Carolina was recently published on-line in the journal Cancer.

The study examined these relationships in more than 1500 women with breast cancer and 1200 controls who did not in the Long Island Breast Cancer Study Project

The results indicated that exercise had no preventative effect when the onset of breast cancer prior to menopause was examined.  However, lifetime exercise was strongly related to cancer-free survival when breast cancer onset after menopause was examined. Child-bearing women who had exercised between 10-19 hours per week prior to and after menopause experienced a 30% reduction in the risk of breast cancer.  Surprisingly, exercise intensity did not seem to affect the relationship.  The data indicated that substantial postmenopausal weight gain may eliminate the benefits of regular exercise.

These results are strong evidence that exercise and weight maintenance are powerful factors in the prevention of breast cancer.

Read more about the study here.

Marathon Runner Deaths Remain Relatively Low Despite Large Increases in Participation

In 2000, 299,000 marathon runners lined up at starting lines all over the United States.  By 2009, the number of marathon runners had increased to over 473,000.  Researchers at the Johns Hopkins School of Medicine performed an epidemiological analysis of the 3.7 million marathon participants in this ten-year span and identified 28 runners who died either during the marathon or in the 24 hours following the race.  These deaths included 6 women and 22 men.

Over the entire decade, the overall death rate was 0.75 deaths per 100,000 finishers, with a rate of 0.98 for men and 0.41 for women.   Half of the deaths occurred in participants older than 45 years of age.  And, of this older group almost all deaths were the result of myocardial infarction/atherosclerotic heart disease.  It is reasonable that these causes of death would be more likely to affect men rather than women since men have a much higher risk for cardiovascular disease.  The different death rates for men and women likely reflect the known larger risk of heart disease in men.

Training for a marathon is a physical challenge that requires planning and care.  A thorough physical exam to rule out potentially life threatening heart disease is a wise precaution, particularly for older first-time marathoners.

See the full abstract here.