Different prognosis of left compared to right breast cancer: A systematic review and meta-analysis.

BACKGROUND: There is an ongoing debate in the medical community about the association between the laterality of breast cancer (BC: whether it arises in the left or right breast) and its outcome. This study aims to assess the disparities in overall survival (OS), cardiac mortality, and cancer-specific survival (CSS) between BC affecting the left side and BC affecting the right side. MATERIALS AND METHODS: We conducted a thorough search of databases, such as PubMed, EMBASE, and the Cochrane Library, starting from their inception up until December 1, 2023. The primary outcome was OS. Additional endpoints included cardiac mortality and CSS. RESULTS: The meta-analysis included 50 publications (n = 7,527,156 patients) with similar rates of left and right BCs. Patients with left-sided BC showed a marginally decreased OS (HR = 1.03, 95 %CI 1.01-1.04; P < .01) and a 10% increase in cardiac mortality (HR = 1.1, 95 %CI 1.04-1.16; P < .01). Cancer-specific survival was similar for both groups (HR = 1.01, 95 %CI 0.98-1.03; P = .32). CONCLUSIONS: According to this study, there is a slight increase in mortality and a 10 % rise in cardiac-related deaths associated with left-sided breast cancer compared to right-sided breast cancer.