Obesity May Affect Response to Breast Cancer Treatment
Women who are obese continue to have higher levels of estrogen than women of normal weight even after treatment with hormone-suppressing drugs, raising the possibility that they might benefit from changes to their treatment.
The study, led by a team at The Institute of Cancer Research in London and The Royal Marsden NHS Foundation Trust, found hormone-suppressing drugs did markedly reduce estrogen levels in obese women - but that their levels of estrogen remained more than double those of women of normal weight.
The research, which is published in the Journal of Clinical Oncology, could lead to improvements in doctors' ability to select the most appropriate treatment for overweight and obese women. But scientists stressed the effect of obesity was modest and that women taking breast cancer treatment should not be concerned by the findings.
Over three-quarters of breast cancers require estrogen to grow, so one of the main ways of treating the disease is by blocking the hormone's production or action. Obese women have higher levels of estrogen than women of normal weight, and the new findings show that although their estrogen levels are markedly reduced with hormone-suppressing drugs called aromatase inhibitors, the levels are higher during treatment than those in similarly treated normal weight women.
Senior author Professor Mitch Dowsett, a team leader in the Breakthrough Breast Cancer Research Centre at The Institute of Cancer Research and head of the academic department of biochemistry at The Royal Marsden, said: "We found that women with higher BMIs had more estrogen remaining in their blood after treatment than healthy-weight women, which is consistent with previous suggestions that aromatase inhibitors might be slightly less effective in these women.