Obesity Increases Breast Cancer Risk
Belly Fat, Hip Fat -- All Body Fat Increases Risk
WebMD News Archive
Confirming Risks From Obesity, HRT continued...
Among postmenopausal women:
- Weight at the start of the study was the strongest predictor of the risk of
breast cancer. The researchers found a 65% increase in the risk of breast
cancer for women in the highest weight category compared with women in the
lowest weight category.
Being overweight or obese (a BMI of more than 25) was a strong
risk factor for breast cancer -- increasing risks by more than 30%.
Among women who had used hormone replacement therapy (HRT)
during the study period, body fat was inversely associated with the risks of
breast cancer. In other words, the researchers showed that obese postmenopausal
women who were using HRT had a 34% reduction in breast cancer risk, compared
with lean women.
Among premenopausal women:
"[Body size] was more strongly associated with breast
cancer risk in post-menopausal than in pre-menopausal women," writes
Lahmann. Her results support the theory that excess estrogen exposure increases
a woman's breast cancer risk.
Also, tall women were more likely to develop breast cancer --
whether before or after menopause, she notes. Factors that influence height,
like bone growth, may also influence breast cancer. Birth weight, diet, and
infections during fetal development or in childhood could play a role.
In premenopausal women, obesity creates irregular menstrual
cycles and more fertility problems, she explains. These women are likely having
fewer ovulation cycles, which means they have less cumulative exposure to
estrogens -- thus they have less breast cancer risk.