Compared to their normal-weight counterparts, overweight and obese women who were previously diagnosed with breast cancer are more likely to have their disease return or to die of cancer. Those are the results of a new observational study, published in the journal Cancer, which investigates the link between weight and breast cancer.
For the study, researchers from the Montefiore Einstein Center for Cancer Care in New York analyzed data on nearly 5,000 women with stage I, II, and III breast cancer who received standardized treatment. Of these, approximately one-third were obese and another one-third were overweight.
The results showed that, compared to women of normal weight, obese women were 40 percent more likely to have their breast cancer recur over the eight-year study period, and were also 69 percent more likely to die from breast cancer or any other cause.
Researchers found that the link was especially strong for women with estrogen receptor positive cancer which comprises about two-thirds of all breast cancers while the association between weight and cancer recurrence or death was not as clear for women with non-estrogen dependent types of cancers.
Although causation cannot be inferred from this study, evidence has shown that women carrying extra fat produce more estrogen a factor that, according to lead author Dr. Joseph Sparano, may be fueling the growth of the estrogen receptor positive tumor.
We already know that obesity in the postmenopausal years carries an increased risk for the development of breast cancer, says ACSH's Dr. Gilbert Ross. This study gives some support to the theory that weight (or BMI) may also be considered as a risk factor linked to breast cancer recurrence and death. This is important information that should be discussed by women with their physicians.