Presence of tumor-infiltrating lymphocytes is an independent prognostic factor in type I and II endometrial cancer.

Objective: Presence of tumor-infiltrating lymphocytes (TIL) is of prognostic importance in a variety of malignancies. This study aims to determine the prognostic value of CD8(+) cytotoxic T-lymphocytes (CTL), FoxP3(+) regulatory T-lymphocytes (Treg) and CD45R0(+) memory T-lymphocytes in endometrial cancer.

Methods: The number of tumor-infiltrating CD8(+), FoxP3(+), and CD45R0(+) T-lymphocytes was determined by immunohistochemistry on tissue microarrays containing tumor material from 368 FIGO stage I-IV endometrial cancer patients. Results from immunohistochemistry were correlated with clinicopathological parameters and survival.

Results: High numbers of intra-tumoral CD8(+) T-lymphocytes, a high CD8(+)/FoxP3(+) ratio and the presence of CD45R0(+) T-lymphocytes were strongly associated with well-known favorable prognostic factors in endometrial cancer. Furthermore, high numbers of CD8(+) T-lymphocytes and a high CD8(+)/FoxP3(+) ratio were associated with a better disease free survival (DFS). High numbers of CD8(+) T-lymphocytes and the presence of CD45R0(+) T-lymphocytes were associated with a prolonged overall survival (OS). In multivariate analysis, high numbers of CD8(+) T-lymphocytes had an independent prognostic impact for overall survival in the entire cohort (HR 0.48, 95% C.I. 0.26-0.89, p=0.019) and in type II endometrial cancer (HR 0.17, 95% C.I. 0.08-0.36, p<0.001). A high CD8(+)/FoxP3(+) ratio was independently associated with improved survival in type I endometrial cancer (HR 0.44, 95% C.I. 0.23-0.84, p=0.013). CD45R0(+) lymphocytes were an independent factor for improved OS (HR 0.42, 95% C.I. 0.19-0.93, p=0.033).

Conclusion: This study shows that the presence of TIL is an independent prognostic factor in endometrial cancer and indicates an important role for the immune system in endometrial cancer.