Prophylactic contralateral mastectomies are on the rise

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.

Mastectomy patients with favorable prognostic factors (smaller tumor size, negative nodes, lower tumor grade) had a significantly higher contralateral prophylactic mastectomy rate. Such patients are probably more likely to benefit from the procedure because their survival time is longer and thus their subsequent risk of contralateral breast cancer is greater, Dr. Tuttle said.

Ironically, the study found that breast-conserving surgery rates also increased from 1998 through 2003. "We're actually seeing a growing number of women at the extremes," Dr. Tuttle said. "Fewer women are choosing unilateral mastectomy."

Reasons for the increase?

Asked if he thought this development was driven by surgeons or was more patient-motivated, he responded, "I'm not sure. And for that reason, we're initiating prospective research on the decision-making processes leading to double mastectomy."

Dr. Tuttle also expressed concern that bad advice based on misinformation might be a contributing factor to the increasing number of women choosing to have prophylactic mastectomy. In short, he thinks that some women might be choosing this option out of fear, under the misconception that having prophylactic mastectomy will give them a better chance of long-term survival.

Other contributing factors may include greater accessibility to genetic tests and improvements in breast reconstruction.

"We need to have a much better understanding of why more women are choosing double mastectomy. Knowing the reasons may assist physicians in counseling patients to make the best clinical decisions," Dr. Tuttle said.