Modeling Study Indicates Little Survival Difference With Contralateral Prophylactic Mastectomy in Breast Cancer Without BRCA Mutation
In a study reported in the Journal of the National Cancer Institute, Portschy et al found an absolute 20-year overall survival difference of < 1% with contralateral prophylactic mastectomy in women with stage I or II breast cancer without BRCA mutation. The authors had hypothesized that the increased use of the procedure in recent years may be fueled by an exaggerated perceived benefit.
Study Details
In the study, a Markov model was developed to simulate survival outcomes after contralateral prophylactic mastectomy or no contralateral prophylactic mastectomy, with probabilities of developing contralateral breast cancer, dying from contralateral breast cancer, dying from primary breast cancer, and age-specific mortality rates being estimated from published studies.
Small Benefit
The predicted life-expectancy gain from contralateral prophylactic mastectomy ranged from 0.13 to 0.59 years in women with stage I breast cancer and from 0.08 to 0.29 years in those with stage II disease depending on age and estrogen receptor status. Absolute 20-year survival differences ranged from 0.56% to 0.94% in stage I disease and from 0.36% to 0.61% in stage II disease. Absolute 20-year disease-free survival differences ranged from 4.25% to 7.20% and from 2.73% to 4.62%. Overall, contralateral prophylactic mastectomy was more beneficial in younger women, those with stage I disease, and those with estrogen receptor–negative disease.
Sensitivity Analysis
Sensitivity analyses assuming contralateral breast cancer annual risks of 0.2% to 0.7% and contralateral prophylactic mastectomy effectiveness of 80% to 100% showed that the largest absolute survival difference in favor of the procedure was 1.45% on the assumption of 0.7% risk and 100% effectiveness.
The investigators concluded: “The absolute 20-year survival benefit from [contralateral prophylactic mastectomy] was less than 1% among all age, [estrogen receptor] status, and cancer stage groups. Estimates of [life expectancy] gains and survival differences derived from decision models may provide more realistic expectations of from [contralateral prophylactic mastectomy].”
Todd M. Tuttle, MD, of University of Minnesota, is the corresponding author for the Journal of the National Cancer Institute article.
The authors declared no conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
