Cancer-Related Mortality Is Similar in Breast Cancer Patients Who Underwent Lumpectomy and Uni- and Bilateral Mastectomy

Giannakeas V, Lim DW, Narod SA. Bilateral Mastectomy and Breast Cancer Mortality. JAMA Oncol. 2024;10:1228-1236.

Khan SA, Kocherginsky M. Contralateral Breast Cancer Remains a Complex Biologic Conundrum. JAMA Oncol. 2024;10:1175-1177.

The study reported in this article used data from the SEER database (n = 661,270) to identify patients who were diagnosed with ductal carcinoma in situ or breast carcinoma between 2000 and 2009.

Three comparison groups were formed using patient matching statistical techniques: patients who underwent lumpectomy, unilateral mastectomy, and bilateral mastectomy. Patients were followed out to 20 years and the main outcome of interest was breast cancer-related mortality.

The data analysis showed that the risk of contralateral breast cancer in patients who underwent lumpectomy or unilateral mastectomy was 6.9%. Rates of breast cancer-related mortality were similar in all three groups over the follow up interval.

The authors concluded that bilateral mastectomy protected against development of contralateral breast cancer but did not reduce breast cancer-related mortality.

In the editorial that accompanied the article, Khan and Kocherginsky noted that a tenable explanation for these findings is that mortality is primarily determined by the biology of the tumor that was diagnosed first. They stressed the fact that data on endocrine therapies used in this patient group were not available and suggested that the value of the data would be improved if the recurrence and mortality rates were timed from the diagnosis of the primary tumor as well as the time of diagnosis of the contralateral breast cancer.