MINNEAPOLIS—A new study shows that more women with unilateral breast cancer are electing to have the other breast removed as well. The rate rose from 1.8% in 1998 to 4.5% in 2003.

Lead author Todd M. Tuttle, MD, chief of surgical oncology, University of Minnesota Medical School and Cancer Center, told Oncology NEWS International that he initiated the study because so many patients were requesting contralateral mastectomies, even though there is no evidence that the aggressive procedure improves survival in these women.

SEER data reviewed

The investigators reviewed the SEER database for patients with unilateral breast cancer diagnosed from 1998 through 2003. Dr. Tuttle said the main strength of SEER is that the database is population-based, providing accurate data on cancer treatment trends. "However," he added, "the main weakness of SEER is that detailed patient and tumor information is not available."

The researchers identified 152,755 patients who were diagnosed with stage I, II, or III unilateral breast cancer and treated with surgery. Most chose either breast-conserving surgery (57.8%) or unilateral mastectomy (38.9%). However, 4,969 (3.3%) elected to have contralateral prophylactic mastectomy (J Clin Oncol, published ahead of print, as 10.1200/JCO.2007.12.3141).

Women who had mastectomy rather than lumpectomy for the breast with cancer were more likely to choose contralateral mastectomy (7.7% over the entire 6 years). In that group, the double mastectomy rate went from 4.2% in 1998 to 11% in 2003.

Dr. Tuttle and his associates found that the rate of contralateral prophylactic mastectomy doubled for all stages of breast cancer during their 6-year study. "More important, the trend is increasing, showing no sign of leveling off," he said.

The patients who elected for prophylactic contralateral mastectomy tended to be younger and white, and were more likely to have lobular-type histology and a previous cancer diagnosis.