PAM50 Intrinsic Subtypes and Immunity Status in Prognosis of Triple-Negative Breast Cancer: A Retrospective Cohort...

Background: Although triple-negative breast cancer (TNBC) patients commonly receive adjuvant chemotherapy after surgery, their prognoses vary. This study aimed to investigate how the intrinsic subtypes of TNBCs and immune status of patients affect their prognosis. Methods: A total of 111 TNBC patients were retrospectively analyzed at Peking Union Medical College Hospital from 2002 to 2014. All underwent surgery and received adjuvant chemotherapy per NCCN guidelines. Intrinsic subtypes (luminal A, luminal B, HER2-enriched, and basal-like) were identified using PAM50 profiling. Recurrence-of-risk (ROR) scores were classified into high, intermediate, and low. Immune status was assessed via a 17-gene panel and categorized as immune-strong or immune-weak. Statistical analyses included chi-square tests, Kaplan-Meier curves, log-rank tests, and Cox regression. Results: All four PAM50 subtypes were present, with basal-like being the most common (77%). Luminal A patients with low-to-intermediate ROR scores showed worse outcomes than other subtypes (DFS, p = 0.123; OS, p = 0.170). Unexpectedly, high-ROR patients had the longest DFS (p = 0.042). Immune-strong status correlated with improved DFS and OS in stage IIB-III patients (DFS, p = 0.029; OS, p = 0.003), and was associated with higher TILs (p = 0.015) and PD-L1 expression on tumor cells (p = 0.022). Conclusions: Multigene-based assessment of molecular subtype and immune status provides important prognostic insight into TNBC and may guide adjuvant treatment decisions, particularly in non-basal-like subtypes.