Prognostic Performance of the Residual Cancer Burden Index With Respect to Molecular Breast Cancer Subtypes.

Objective: The use of neoadjuvant chemotherapy (NAC) has improved outcomes in breast cancer (BC). The residual cancer burden index (RCB) predicts prognosis. This study evaluated RCB as a prognosticator in BC subtypes treated with NAC.

Materials and methods: A retrospective cohort of BC patients was analyzed. Five-year distant recurrence-free survival (DRFS), disease-free survival (DFS), and overall survival (OS) were analyzed. Statistical analyses included descriptive statistics, ANOVA, chi-square test, Fisher's exact test, Kaplan-Meier curves, Log-Rank test, and Cox regression.

Results: Among 562 women, RCB correlated with BC subtypes and predicted worse DRFS, DFS, and OS. In stratified analyses by molecular subtype, the association was significant only for luminal B and triple-negative subtypes, with inconsistent findings for luminal A and human epidermal growth factor type 2-overexpressed subtypes.

Conclusion: The RCB index was shown to be a prognostic marker in BC in a Brazilian population with BC. Significant associations were found only for the luminal B and triple negative subtypes. Further research is required to investigate the prognostic utility of RCB in other larger populations.