Every woman, myself included, wants to know what she can do to avoid getting breast cancer -- all the while knowing that breast cancer often can't be avoided. With this in mind, I tread carefully in reporting on an intriguing new paper that calculates how much "controllable" risk factors weigh in to our breast cancer risk.
The German study published today in the journal Cancer Epidemiology compared 6,386 healthy women with 3,074 breast cancer patients who had been diagnosed after the onset of menopause. The researchers then calculated the percentage of cancer cases attributed to a particular risk factor or a particular combination of risk factors.
The researchers determined that about 37 percent of all postmenopausal breast cancers are caused by factors women can't change, such as their family history, their age, or the age of their first and last menstrual period. But they also determined that nearly 30 percent of breast cancers could be prevented by modifying certain lifestyle habits. (The other 33 percent of breast cancers have undetermined causes.)
So which lifestyle habits play the biggest role in breast cancer risk? The use of hormone replacement therapy and a lack of physical activity, according to the study. Interestingly, excess body weight and alcohol consumption -- two lifestyle habits that have also been attributed to breast cancer risk -- played only a minor role, at least in the breast cancer patients who took part in this study.
Many women are already shunning hormone therapy unless they have severe menopausal symptoms because of its link to heart attacks, strokes, and breast cancer. But the vast majority of older women could probably benefit from more exercise. How much? Based on previous research, the National Cancer Institute recommends four or more hours a week of steady activity like brisk walking, swimming or biking.