CD5 Immunoreactivity Is Associated With Longer Overall Survival in Thymic Carcinoma: A Brief Report

Thymic carcinomas are a heterogeneous group of potentially aggressive malignancies. We aimed to determine the prognostic significance of CD5, CD117, EZH2, POU2F3, BAP1, and MTAP immunohistochemical staining in thymic carcinomas. Immunohistochemistry was performed on 36 thymic carcinomas from patients with retrospectively collected survival data. Thirteen cases (36%) had CD5 staining in 50% or more tumor cells, considered positive staining. Positive CD5 immunohistochemical staining was significantly associated with longer overall survival (hazard ratio = 0.18, 95% confidence interval: 0.03-0.63, p = 0.005). Three-year overall survival was 48% (95% confidence interval: 27%-70%) for CD5 negative cases, and 100% for CD5 positive cases. Positive CD5 staining remained significantly associated with overall survival after adjusting for neoadjuvant treatment, M-stage, or incomplete resection (p = 0.01). The remaining immunohistochemical markers were not significantly associated with overall survival. Our study supports the notion that CD5 immunohistochemistry may have utility as a novel prognostic marker for thymic carcinoma.