The Difference of RCB 0 and RCB I in Prognosis of Breast Cancer After Neoadjuvant Therapy: A Meta-Analysis.

Background: The use of the residual cancer burden (RCB) for assessing breast cancer after neoadjuvant therapy (NAT) is increasingly common, but the prognostic difference between RCB 0 and RCB I is unclear.

Methods: We systematically reviewed literature from PubMed, Embase, Web of Science, and oncology conferences until September 24, 2023. We used fixed- and random-effects models to calculate hazard ratio (HR) with 95% confidence interval (CI) for event-free survival (EFS), overall survival (OS), and distant disease-free survival (DDFS).

Results: Our meta-analysis, encompassing 19 studies with 5894 patients, revealed that in the general population, RCB I had worse EFS (HR = 2.13; 95% CI: 1.75-2.58), OS (HR = 2.08; 95% CI: 1.48-2.93), and DDFS (HR = 2.10; 95% CI: 1.65-2.67) than RCB 0. Consistent with results from the general population, RCB I exhibited poorer EFS, OS, and DDFS in human epidermal growth factor 2-positive (HER2+) subtype and triple-negative breast cancer (TNBC) compared to RCB 0. Conversely, luminal subtype with RCB 0 and RCB I showed similar EFS (HR = 1.04; 95% CI: 0.62-1.72).

Conclusions: RCB I experienced a poorer prognosis compared to RCB 0 in the general population, a pattern also observed in the HER2+ subtype and TNBC. However, no significant prognostic disparity was noted between RCB 0 and RCB I in the luminal subtype.