You can somehow reduce your risk of breast cancer if you start exercising, and it’s never too late! This information comes from a prospective cohort study in France that included 59,000 postmenopausal female subjects. The researchers found that women who exercised at a moderate intensity – walking an average of at least 4 hours per week – had a 10% lower risk of invasive breast cancer compared to women who did not exercise much, with an HR of 0.90. More significantly, the risk reduction occurred only in the “near future” (within the last 4 years). More significantly, the risk reduction was only seen in postmenopausal women who had been active “recently” (within the last 4 years). However, for women who reached this level of exercise 5 to 9 years ago but then slackened off, there was no reduction in the risk of breast cancer, suggesting that only recent exercise and sustained exercise can reduce the risk of breast cancer. In an email to Medscape Medical News, Mesrine, a senior researcher from the Gustave Roussy Institute in France, suggested that “women who are not yet exercising can benefit from doing so immediately, even if they have never exercised before. Doctors can even tell patients that exercise doesn’t require any equipment.” Dr Mesrine points out that there is no need for complicated or strenuous exercise. All that is needed is to walk at least 30 minutes a day, such as getting off the bus one stop earlier, or not driving when going shopping. The study was published in the Aug. 11 online issue of the journal Oncology Epidemiology Biomarkers and Prevention. The researchers analyzed data from 59,308 women from a biennial health and lifestyle questionnaire administered between 1993 and 2005. The average duration of postmenopause was about 8.5 years. During the study period, 2,155 women developed invasive breast cancer. Dr Mesrine and colleagues noted that the vast majority of female subjects in the study cohort were schoolteachers, who were covered by the National Health Insurance Fund. The female subjects in the study cohort were all very slender teachers. Approximately 3/4 of the subjects in the cohort had a body mass index (BMI) of less than 25 kg/m2. The type of activity reported by the subjects in their 2-year questionnaires was walking or cycling. In the study, there was no significant “dose-response association”, i.e., an increase in exercise did not reduce the risk of developing breast cancer. However, the researchers noted that there was limited information about women’s leisure activities from the questionnaires collected, and Dr Mesrine and colleagues noted that “our results suggest that moderate levels of physical activity are associated with a reduced risk of radiation” and that the study also addressed some of the unanswered questions in the previous literature on breast cancer and exercise. The study also sheds light on some unanswered questions in the previous literature on breast cancer and exercise. Agnès Fournier (another researcher) from the Gustave Roussy Institute in France noted in a news release that exercise reduces the risk of breast cancer in women after menopause, however, it is unknown how long after exercise initiation this association begins and how long the effect is maintained after exercise stops. The study also suggests that the onset of benefit is relatively rapid (starting as early as 4 years after exercise initiation) and that the risk-reducing effect disappears within a few years of exercise cessation. Dr Mesrine and colleagues put their findings into practice. They note that “most members of the study team exercised regularly, as I do, at least to the minimum intensity recommended by WHO. Some members chose to cycle to work, others chose to walk to work, and most of them also did other exercises. Recently, there has been a gradual increase in the number of exercise programs in France. In the past decade, great strides have been made in encouraging the nation to exercise. For example, in most cities, bicycles can be rented at very low prices and can be returned anywhere.