Again, more research finding that being overweight or obese is associated with an increased risk of breast cancer - specifically higher risk of invasive breast cancer in postmenopausal women. They found that the heavier the woman, the higher the risk, but the risk did not vary with hormone therapy use or race and ethnicity. From Medical Xpress:
An analysis of extended follow-up data from the Women's Health Initiative clinical trials suggests that postmenopausal women who were overweight and obese had an increased risk of invasive breast cancer compared to women of normal weight, according to an article published online by JAMA Oncology. Obesity is a major public health problem in the United States and obesity has been associated with breast cancer risk in observational studies, systematic reviews and meta-analyses.
The Women's Health Initiative (WHI) protocol measured height and weight, baseline and annual or biennial mammograms, and breast cancer in 67,142 postmenopausal women enrolled from 1993 to 1998 with a median of 13 years of follow-up. There were 3,388 invasive breast cancers. Analysis by the authors found:
- Women who were overweight (body mass index [BMI] 25 to < 30); obese, grade 1 (BMI 30 to < 35); and obese, grade 2 plus 3 (BMI > 35) had an increased risk of invasive breast cancer compared to women of normal weight (BMI < 25)
- The risk was greatest for women with a BMI greater than 35; those women had a 58 percent increased risk of invasive breast cancer compared with women of normal weight (BMI < 25)....
- Obesity was associated with markers of poor prognosis; women with a BMI greater than 35 were more likely to have large tumors, evidence of lymph node involvement and poorly differentiated tumors
- Women with a baseline BMI of less than 25 who gained more than 5 percent of body weight during the follow-up period had an increased risk of breast cancer....