Potential role of tumor-infiltrating T-, B-lymphocytes, tumor-associated macrophages and IgA-secreting plasma cells in long-term survival in the rectal adenocarcinoma patients.

Aims: Many studies investigated the associations between the role of immune cells of rectal cancer microenvironment and survival during the first 5 years post-surgery. This is problematic as this disease has the potential to progress even after 5 years after relapse and infiltrating immune cells could play key roles. Therefore, this retrospective study investigates expression and roles of tumor-infiltrating T-lymphocytes (TIL-T), tumor-infiltrating B-lymphocytes (TILB), IgA plasma cells (IgA PC) and tumor-associated macrophages (TAM) in patients with or without progression over 5 years survival with rectal adenocarcinoma.

Main Methods: Here we used immunohistochemical staining of CD3, CD20, IgA, CD68 positive cells and its detection in rectal cancer stroma. Data was analyzed using Mann Whitney U test, ROC, survival and Cox's regression analysis.

Key Findings: The number of TIL-T (p = 0.0276), TIL-B (p < 0.0001) and IgA PC (p = 0.015) immune cells was significantly higher in rectal cancer stroma of patients with favorable outcome. Univariate Cox's regression analysis revealed a predictive role of TIL-T (HR = 0.482; 95% CI, 0.303 to 0.704; p < 0.0001), TIL-B (HR = 0.301; 95% CI, 0.198 to 0.481; p < 0.0001) and IgA-PC (HR = 0.488; 95% CI, 0.322 to 0.741; p < 0.0001). Multivariate Cox's regression analysis showed prognostic role of TIL-B (HR = 0.940; 95% CI, 0.914 to 0.968; p < 0.0001) and IgA-PC (HR = 0.985; 95% CI, 0.975 to 0.996; p = 0.006) play role in long time survival.

Significance: CD20 TIL-B and IgA cells have significant associations with long -term survival of patients with rectal cancer, with potential therapeutic intervention in cancer immunotherapy.