Obesity Doesn't Hamper Tamoxifen Therapy
Being Obese Won't Decrease Effectiveness of Breast Cancer Treatment Drug
Sept. 30, 2003 -- Obesity alone shouldn't lessen the
effectiveness of the popular breast cancer treatment drug tamoxifen, but
overweight women with breast cancer might face other risks.
Previous studies have suggested that there was an increased
risk of breast cancer recurrence and death among obese women compared with lean
women. This is because fat tissue produces estrogen, and estrogen plays a role
in some breast cancers.
But a new study shows that obesity isn't associated with any
higher risk of recurrence of breast cancer among women with early-stage,
hormone-responsive breast cancer, nor does it decrease the effectiveness of the
breast cancer treatment drug tamoxifen.
Tamoxifen is commonly prescribed to treat or prevent breast
cancer recurrence in high-risk women. Breast cancer can respond to estrogen;
tamoxifen prevents breast cancer cells from binding to estrogen. It can stop
cancer cells from growing and prevent the recurrence of the disease.
Obesity Carries Its Own Risks
Researchers say previous studies on obesity and breast cancer
risks included women with different stages of breast cancer, which may have
clouded the results because obese women are more likely to have a more advanced
stage of breast cancer than lean women.
In this study, researchers looked at 3,385 women with
early-stage hormone-responsive disease, a form of breast cancer that depends on
estrogen to grow and is responsive to treatment with tamoxifen. Researchers
followed the group for an average of about 14 years and then compared the risks
of breast cancer recurrence, development of tumors in the opposite breast
(known as contralateral tumors), of other new cancers, and of death.
The results appear in the Oct. 1 issue of the Journal of the
National Cancer Institute.
The study showed that obese women had no higher risk of cancer
recurrence or death due to cancer than lean women. But obese women did have a
higher risk of developing other types of cancer or a tumor in the opposite
breast and were more likely to die from any cause compared with non-obese
Obesity was defined as having a body mass index (BMI, a measure
of weight in relation to height) of 30 or higher.
The study also showed that treatment with the breast cancer
treatment drug tamoxifen reduced the risk of breast cancer recurrence or death
due to breast cancer regardless of the women's BMI.
Researcher James J. Dignam, PhD, of the University of Chicago,
and colleagues, say the findings support the use of tamoxifen in breast cancer
patients of all body types. But they also warn that because obesity increases
the risk of second cancers and death from any cause, it may affect the
long-term health of breast cancer survivors.