Is programmed death-ligand 1 positivity a predictor of poor survival in patients with different histological subtypes of pancreatic cancer?

Objective: Pancreatic cancer is the cancer type with the highest mortality rate worldwide, and despite advances in treatment, molecular biomarkers are needed for both early diagnosis for developing targeted therapies and improving survival rates in this challenging malignancy. In our study, the contributions of programmed death-ligand 1 (PD-L1) expression to the determination of pancreatic cancer subtypes and patient prognosis and its impact on survival were investigated.

Material and methods: Paraffin-embedded tissues from 92 patients diagnosed with pancreatic cancer were included in this study. Tumor-infiltrating lymphocytes (TILs) and lymphocytes in the stromal area within the tumor borders were scored as stromal TILs; lymphocytes in tumor islands were scored as intratumoral TILs. Staining in each area was scored as a percentage, and staining with a score of 5 or more in tumor and immune cells for PD-L1 was scored as positive.

Results: After staining, a score of 5 or more with tPD-L1 staining was used to identify one patient as having micropapillary adenocarcinoma, three patients as having ductal adenocarcinoma, and four patients as having signet ring cell carcinoma. When the clinical parameters and outcomes were compared, a statistically significant difference was found between the histopathologic type of signet ring cell carcinoma and poor differentiation and positivity of PD-L1 expression (P < 0.05). Survival was significantly influenced by tumor location, histopathological subtype, degree of differentiation, PD-L1 expression, and tumor size, with tumor size being the most critical factor (P < 0.05).

Conclusion: Our findings suggest that PD-L1 positivity is notably prevalent in signet ring cell carcinoma of the pancreas and is strongly associated with poor survival outcomes. Given these results, further studies with larger patient cohorts are warranted to validate these observations and explore potential therapeutic implications.