We are finally beginning to recognize that diet and lifestyle are related to breast cancer risk. Data obtained from 90,509 women participating in the E3N cohort study indicates that regular, vigorous exercise may reduce a woman’s chance of getting breast cancer. The study was published in Cancer Epidemiology, Biomarkers and Prevention (2006; 15(1): 57-64). It followed the subjects, aged between 40 and 65 years (at the start of the study), for 12 years. Frequency and intensity of physical activity was assessed. During that time, there were 3,424 cases of breast cancer diagnosed. There was an inverse relationship between the amount of physical activity and the incidence of breast cancer. Women who reported engaging in vigorous recreational activities more than five hours per week had a relative risk of 0.62, as compared with women who reported engaging in no recreational activities.

Women who regularly exercised in the year before being diagnosed with breast cancer have into a higher survival rate compared to sedentary women, according to the journal Cancer (October 15, 2006). The study looked at data from women aged 20 to 54 who were diagnosed with breast cancer. The women were asked about how often they exercised moderately or vigorously at ages 13, 20 and in the year before their diagnosis. Those who exercised had a better survival rate, and this effect was especially true for women who were overweight (a BMI > 25).

The women rated the most active in the year before diagnosis (the top 25%–in terms of activity) were more than 20% more likely to survive than the most sedentary 25%. For women who were overweight, the most active were 30% more likely to survive than the least active. The amount of exercise earlier in life did not seem to have an effect on survival rates.