Routine Chemo for Breast Cancer Disputed
For post-menopausal women with estrogen-sensitive breast cancer, chemotherapy may offer no benefit, and a five-year course after surgery of tamoxifen, which blocks the hormone, may be the only treatment needed, a study shows.
The finding, appearing last week in the Journal of the National Cancer Institute, could mean that some of the thousands of American women diagnosed each year with breast cancer could avoid the debilitating side effects of drugs that kill cancer cells and damage other cells in the body.
The study also found that for post-menopausal women whose breast cancer was not affected by estrogen, chemotherapy followed by tamoxifen offered the best hope of disease-free survival. Tamoxifen works by blocking the action of estrogen, a hormone that can promote the growth of cancer cells.
“We’re hoping this study will question the routine use of chemotherapy in the ER-positive [estrogen-sensitive] group,” said Richard D. Gelber, a biostatistician at the Dana-Farber Cancer Institute in Boston and one of dozens of co-authors. “This is the largest study ever concentrating on this population.”
Dr. Andrew D. Seidman, a breast cancer specialist at Memorial Sloan-Kettering Cancer Center in New York City, said the study “will reaffirm the way that many oncologists are now practicing” and should help doctors base cancer therapies on the specific characteristics of their patients.
It shows that chemotherapy is appropriate for some women but not others and that patients who need the therapy can be specifically identified based on the estrogen sensitivity of their tumors and on other factors, Seidman said.
The study, compiled by researchers from nine countries, was limited to breast cancer surgery patients who had completed menopause and whose disease had not spread to the lymph nodes. About 43% of the about 184,000 women in the United States diagnosed with breast cancer each year fit this category.
Researchers further divided the 1,669 patients in the study into groups based on whether their cancers were affected or not affected by estrogen.
There were 382 in the study whose tumors were not affected by estrogen, described in medical terms as being estrogen receptor negative, or ER-negative. There were 1,217 who were ER-positive. For the remaining 70 patients, the ER status was unknown.
About half in each of these groups were treated with chemotherapy followed by five years of tamoxifen. The other half of each group received tamoxifen only.
