Invasive Stratified Mucin-producing Carcinoma of the Uterine Cervix: Comparison of Its Clinicopathological Characteristics and Programmed Death-ligand 1 Expression Status With Those of Other Endocervical Adenocarcinomas.

Background/aim: Invasive stratified mucin-producing carcinoma (ISMC) is a rare but aggressive variant of endocervical adenocarcinoma (EAC). The aim of this study was to investigate the differences in clinicopathological features, patient outcomes, and programmed death-ligand 1 (PD-L1) expression among ISMC, usual-type EAC (UEA), and gastric-type EAC (GEA).

Patients and methods: PD-L1 22C3 immunostaining was performed using 20 ISMCs, 20 UEAs, and 20 GEAs. Combined positive score (CPS) method was used to assess PD-L1 immunoreactivity.

Results: ISMC was diagnosed at a younger age and showed a more advanced stage and shorter survival than UEA. The disease-free survival (DFS) and overall survival (OS) rates of ISMC patients were lower than those of UEA but comparable to those of GEA. ISMC type was an independent prognostic factor for predicting short DFS [hazard ratio (HR)=2.790, 95% confidence interval (CI)=1.153-6.756] and OS (HR=6.071, 95%CI=1.257-29.327). All ISMCs showed PD-L1 over-expression with a mean CPS of 44.5 (range=10-100), which was higher than those of UEA (mean CPS=8.2) and GEA (mean CPS=6.5). PD-L1 positivity (CPS≥1) was also an independent prognostic factor for worse OS (HR=2.472, 95%CI=1.097-5.570). Despite PD-L1 over-expression, ISMC patients treated with pembrolizumab showed no clinical response.

Conclusion: All examined ISMCs over-expressed PD-L1. ISMC showed higher PD-L1 expression than UEA and GEA and worse survival than UEA. PD-L1 over-expression was found to be a significant predictor for worse DFS and OS in patients with ISMC. Our data suggest that PD-L1 over-expression is associated with poor ISMC prognosis.