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Treatment-Induced Amenorrhea: Adverse Effect or Benefit? - San Antonio Breast Cancer Symposium

Posted on: Saturday, 16 December 2006, 12:00 CST

SAN ANTONIO, Dec. 16 /PRNewswire/ -- Research presented today at the 29th Annual San Antonio Breast Cancer Symposium suggests that a common and alarming side effect of chemotherapy may in fact contribute to better treatment outcomes in breast cancer patients.

In addition to the better-known side effects of chemotherapy, such as hair loss and nausea, breast cancer patients receiving standard therapies frequently experience amenorrhea, the cessation of normal menstrual periods. Amenorrhea may be only temporary or may last for an extended period of time. This can be particularly upsetting for women who still wish to have children.

Michael Gnant, MD, representing the Austrian Breast and Colorectal Cancer Study Group (ABSCG), presented long-term results from a clinical trial showing that patients who experience amenorrhea as a result of chemotherapy are less likely to have a recurrence of their cancer than those who retain normal menstruation. Most breast cancers are estrogen-responsive; that is, they grow in response to estrogen in the body. Estrogen levels are significantly reduced with amenorrhea, and Dr. Gnant believes that this is the cause of the better treatment outcomes.

The ABCSG-05 trial treated 1,034 premenopausal women with either standard combination chemotherapy (cyclophosphamide, methotrexate, and 5-fluorouracil) or a combination of goserelin and tamoxifen. Goserelin specifically suppresses the function of the ovaries, including the production of estrogen. Patients receiving standard chemotherapy received 6 rounds of treatment. Goserelin was administered for 3 years and tamoxifen was administered for 5 years. Amenorrhea was defined as the complete cessation of menstrual periods for at least 4 months after the completion of 3 months of therapy.

The women in this study have now been followed for 11 years since treatment. About two thirds of the patients who received standard chemotherapy and all of the patients receiving the goserelin/tamoxifen combination experienced amenorrhea. The presence of amenorrhea in both treatment groups was associated with a significant increase in relapse-free survival, a measure of the amount of time before cancer recurrence.

The improved outcome associated with treatment-induced amenorrhea was related to age, and was most striking in younger patients (under the age of 40). Amenorrhea reduced the relapse risk in patients less than 40 years of age by approximately 44%. Improved treatment outcome was also associated with whether a patient's tumor had a specific type of protein (HER2) on the cell surface-patients who were HER2-negative tended to have an improved treatment response associated with amenorrhea.

Based on the results of this study, Gnant and colleagues have suggested that additional treatment with a drug such as goserelin might be beneficial in patients receiving chemotherapy who do not experience treatment-induced amenorrhea. Clearly, however, this is something that should be discussed by a patient and her doctor. Especially in younger women for whom such treatment would be most effective, the suppression of ovarian function can be an emotionally charged issue, and a careful assessment of risks and benefits is necessary.

San Antonio Breast Cancer Symposium

CONTACT: Marybeth Libonate of M2 Communications for San Antonio BreastCancer Symposium, +1-201-433-9400

Web site: http://www.sabcs.org/

Source: PRNewswire

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