A weight loss of at least 10 pounds will significantly decrease the risk of early-onset breast cancer in women who carry a BRCA mutation, results of a large case-control study suggest.
Early-adulthood weight loss is especially important for women with the BRCA1 mutation, wrote Joanne Kotsopoulos, a doctoral student at the University of Toronto, and her colleagues (Breast Cancer Res. 2005;7:R833–43; doi 10.1186/bcr1293, online at http://breast-cancer-research.com/content/7/5/R833
The investigators examined early-onset breast cancer in 1,073 matched case-control pairs; about 75% had mutations and 25% had BRCA2 mutations.
Weight loss of at least 10 pounds between age 18 and 30 resulted in an overall 34% reduction in breast cancer risk. The risk reduction was greater (63%) for breast cancers diagnosed between age 30 and 40, but not significant for breast cancer diagnosed after age 40. Women with the BRCA1 mutation experienced the greatest risk reduction with weight loss (65%). The risk reduction was nonsignificant (22%) for women with the BRCA2 mutation.
Weight gain of more than 10 pounds also canceled out any protective effect of parity. Gaining more than 10 pounds and having two full-term pregnancies increased the risk of early-onset breast cancer by 44%, compared with women who gained minimal weight and had at least two pregnancies.
About 40% of the women who lost 10 or more pounds had a body mass index of 25 kg/m