Tumour-infiltrating Lymphocytes: A Prognostic Factor of PSA-free Survival in Patients with Local Prostate Carcinoma Treated by Radical Prostatectomy

Abstract

Aim: The aim of the study was to evaluate the prognostic significance of tumour-infiltrating lymphocytes (TILs) in local prostate cancer (PC). Materials and Methods: TILs were counted and routine histological variables were assessed from radical prostatectomy specimens in 188 cases of PC. Immunohistochemical (IHC) characterisation of the lymphocytes was done by using CD4 and CD8 antibodies for detection of T lymphocytes and CD20 antibody for B lymphocytes in tissue microarray construction. The results of the lymphocyte analyses were compared to other prognostic factors and PSA recurrence-free survival (RFS). Results: Strong expression of TILs, CD4, CD8 and CD20 lymphocytes were seen in 28%, 33%, 35% and 15% of the cases, respectively. CD4 and CD8, as well as CD4 and CD20, lymphocytes were correlated to each other (p<0.0001), but not to clinical or histopathological parameters. Weak expression of TILs was correlated with intracapsular carcinoma (p=0.004), while perineural invasion (p=0.017) and capsular invasion (p<0.0001) were related to strong expression of TILs. Shortened PSA RFS was associated with strong expression of TILs (p=0.005). In Cox regression analysis, independent predictors of shortened PSA RFS were strong expression of TILs (p=0.012) and high Gleason score (p<0.001). Conclusion: TILs are an independent predictor of short PSA RFS in patients with local PC treated by radical prostatectomy.