A study in Breast Cancer Research 2010 shows that obesity, inactivity and excessive alcohol consumption increases one's risk for breast cancer. It does matter if there is a family history of breast cancer or not. There were 85,644 postmenopausal women enrolled in this study. Approximately 25% of the sample were over the age of 70 years at baseline, approximately 83% were of white racial/ethnic background, and approximately 39% had completed a four-year college degree. Twelve percent reported a family history of breast cancer (in a first-degree relative at the age of 45 years or more). Eighty-seven percent of participants drank less than seven alcoholic beverages per week, 24% exercised for at least 20 minutes at moderate/vigorous intensity at least five times per week, and 23% maintained a healthy weight. The rate of invasive breast cancer among women with a family history of breast cancer who participated in exercise, less than 7 drinks a week and were at their ideal weight was 5.94 per 1,000 woman-years, compared with 6.97 per 1,000 woman who participated in none of the behaviors. The rate among women with no family history for breast cancer who participated in all three behavioral conditions was 3.51 per 1,000 woman-years compared to 4.67 per 1,000 woman for those who participated in none of the behaviors.
This study indicates that a healthy lifestyle really does reduce one's risk for breast cancer regardless of a family history.