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RISK OF LEUKEMIA AFTER TREATMENT FOR BREAST CANCER.

Radiotherapy and certain cancer chemotherapies increase the risk of a subsequent leukemia. However, it has been uncertain whether such risks apply to use of these therapies in women with breast cancer.

This case-control study identified 82,700 women who were diagnosed with breast cancer between 1973 and 1985 in five different areas of the U.S. and survived at least 18 months after diagnosis. Leukemia subsequently developed in 90 of the women. The researchers compared breast-cancer regimens used in these 90 cases with those used in 264 controls (matched for age, race, and year of diagnosis) in whom leukemia did not develop. The relative risks of acute nonlymphocytic leukemia for patients treated with regional radiotherapy alone, cyclophosphamide alone, combined radiation and chemotherapy, and melphalan alone were 2.4, 3.1, 17.4, and 31.4, respectively.

Although these relative risks are high, the absolute risk of leukemia based on these data is very low (0.1 percent). Moreover, regional radiotherapy and melphalan are rarely used today in breast cancer, and the doses of cyclophosphamide given currently are considerably lower than those used between 1973 and 1985. Thus, the results of this large, well-conducted study are reassuring.

— ALK

Published in Journal Watch General Medicine July 3, 1992

Citation(s):

Curtis RE et al. Risk of leukemia after chemotherapy and radiation treatment for breast cancer. N Engl J Med 1992 Jun 25 326 1745-1751.

• Medline abstract (Free)