December 10, 2010
Alternative Treatments Aid In Breast Cancer Survival
(Ivanhoe Newswire) -- Postmenopausal women fighting a specific form of breast cancer may get some help through innovative use of two enzyme-inhibiting drugs.
In hormone-receptor positive, early-stage breast cancer, estrogen causes tumor growth and must be treated with surgery. Following surgery, patients of this form of breast cancer are therefore administered drugs which seize the production of estrogen for five years. The drugs work by inhibiting the aromatase enzyme, which transforms androgens to estrogens, thus restricting the cancerous effects of estrogen.
Two particular aromatase inhibitors called anastrozole and exemestane were recently compared in an adjuvant clinical trial, and were found to yield similarly high survival rates and ability to prevent the breast cancer from returning. Side effects varied between the two drugs, but both were believed to be an effective treatment.
The comparison was performed in a study conducted by Paul E. Gross, M.D., Ph.D., of the Harvard Medical School in Boston. Since previous research had shown aromatase inhibitors to be more efficient than standard endocrine therapies, Goss and his team took their study a step further by hypothesizing that drugs like exemestane represent another class of aromatase inhibitors entirely, having greater potency and more manageable side effects.
At present, anastrozole and letrozole are the only drugs approved by the FDA as a first-line, adjuvant therapy. Exemestane is only approved when accompanying a standard endocrine therapy called tamoxifen, or when used as a second-line treatment for metastatic breast cancer.
"The difference in the drug class is that anastrozole is a non-steroidal inhibitor and exemestane is a steroidal inhibitor," Goss was quoted as saying.
Goss' hypothesis was tested by the NCIC Clinical Trials Group at Queen's University, Canada. In an expansive, randomized trial, 7,576 participating women were given either anatstrozole or exemestane and the results were compared and analyzed.
"We found that the drugs are comparable in terms of preventing recurrent breast cancer and in overall survival," Goss was quoted as saying. "Osteoporosis was reported less frequently and cholesterol levels appeared to be lower in patients on exemestane than anastrozole."
Over four years of follow-ups confirmed a 91% overall survival rate for the women in the trial. Although many other factors likely contributed the results, such as greater screening and radiation technologies and improved chemotherapy and endocrine therapy, Goss believes that his findings establish the drugs as a viable alternative treatment for hormone receptor-positive, early-stage breast cancer.
SOURCE: 33rd Annual CTRC-AACR San Antonio Breast Cancer Symposium, Dec. 8-12, 2010