Improved Progression-Free Survival Associated with Tumor-Infiltrating Lymphocytes in High-Grade Endometrial Cancer

Tumor-infiltrating lymphocytes (TILs) have emerged as a prognostic marker in endometrial cancer (EC). However, the role of TILs in EC with distinct histology grades and molecular types (such as mismatch repair [MMR] deficiency) has not yet been made clear. We retrospectively included 237 patients with primary EC who underwent a standard staging operation of laparoscopic or laparotomy total hysterectomy and bilateral salpingo-oophorectomy for analyses. An independent pathologist who was blind to the study patients' information reviewed the pathologic slides to assess TILs according to the method introduced by the International Immuno-Oncology Biomarkers Working Group in 2017. The outcomes of interest included both progression-free survival (PFS) and overall survival (OS). The Kaplan-Meier method was used to determine the curves of PFS and OS according to TILs, and also in the relevant subgroups (low-grade vs. high-grade, MMR-proficient vs. MMR-deficient). After a median follow-up duration of 1.82 years, 18 patients had experienced either disease progression or death. Overall, TILs (+) were not associated with PFS or OS. We did observe, however, that TILs (+) were associated with a better PFS (p = 0.045) in patients with high-grade EC, but not in those with low-grade tumors (p = 0.733). The effect of TILs on PFS was not observed in patients with MMR-proficient (p = 0.347) or MMR-deficient (p = 0.168) EC. TILs were associated with a better PFS in patients with high-grade EC. Our results suggest that TILs may be a potential prognostic marker in these patients.

Automated summary

Tumor-infiltrating lymphocytes (TILs) have a prognostic role in endometrial cancer (EC), but their role in EC with different histology grades and molecular types is unclear. This study included 237 patients with primary EC and evaluated TILs using a standardized method. The results showed that TILs were not associated with disease progression in EC overall, but were associated with better progression-free survival in high-grade EC patients.