Increasing evidence suggests that cancer progression is strongly influenced by host immune response, which is represented by immune cell infiltrates. T-lymphocyte-based immunoscore has proved to be a prognostic factor in colon cancer, but its significance in pancreatic cancer is poorly known. Total of 108 patients operated (R0/R1) for pancreatic ductal adenocarcinoma (PDAC) (TNM stage I-II) were included in the study. Immune cell score (IS) was determined by scoring the samples from grade 0 to 4 according to the number of immune cells (CD3 and CD8) in tumor core and invasion margin using tissue microarrays, immunohistochemistry, and digital analysis. Tumors with microsatellite instability were identified by MLH1 immunostaining. High IS and low histological grade were significantly associated with better disease-specific survival (DSS) and overall survival (OS). The 5-year DSS rate for low, moderate, and high IS groups were 5.0, 15.2, and 33.4%, respectively (p = 0.007). The 5-year OS rate for the low, moderate, and high IS groups were 4.2, 13.4, and 31.5%, respectively (p = 0.004). In addition, IS and prognosis varied within a single TNM stage. There was no association between IS and any of the clinicopathological variables. IS was shown to be an independent prognostic factor for better DSS and OS in multivariate analysis, together with the histological grade of the tumor and perineural invasion. Five MLH1-negative tumors (4.6%) were found showing no correlation with IS. IS could be a useful prognostic marker in patients with PDAC treated by primary surgery.

Hyaluronan (HA) accumulation has been associated with poor survival in various cancers, but the mechanisms for this phenomenon are still unclear. The aim of this study was to investigate the prognostic significance of stromal HA accumulation and its association with host immune response in pancreatic ductal adenocarcinoma (PDAC). The study material consisted of 101 radically treated patients for PDAC from a single geographical area. HA staining was evaluated using a HA-specific probe, and the patterns of CD3, CD8, CD73 and PD-L1 expression were evaluated using immunohistochemistry. HA staining intensity of tumour stromal areas was assessed digitally using QuPath. CD3- and CD8-based immune cell score (ICS) was determined. High-level stromal HA expression was significantly associated with poor disease-specific survival (p = 0.037) and overall survival (p = 0.013) In multivariate analysis, high-level stromal HA expression was an independent negative prognostic factor together with histopathological grade, TNM stage, CD73 positivity in tumour cells and low ICS. Moreover, high-level stromal HA expression was associated with low ICS (p = 0.017). In conclusion, stromal HA accumulation is associated with poor survival and low immune response in PDAC.

An immune cell score (ICS) was introduced for predicting survival in pancreatic ductal adenocarcinoma (PDAC). Few studies have compared different methods of evaluating immune infiltrate. This study compared ICSs determined in whole sections or tissue microarray-like hotspots for predicting survival after PDAC surgery. We included in 79 consecutive patients from a single geographical area that underwent surgery for PDAC (R0/R1, stages I–III). We performed digital image analyses to evaluate CD3 and CD8 staining. ICSs were classified as low, moderate, or high, based on the numbers of immune cells in the tumour core and invasive margin. We compared ICS groups determined with the hotspot and whole-section techniques. Associations between ICS and survival were analysed with Cox regression models, adjusted for sex, age, tumour stage, differentiation grade, perineural invasion, and resection radicality. In hotspot ICS analysis, 5-year overall survival rates for low, moderate, and high groups were 12.1%, 26.3%, and 26.8%, respectively ( p = 0.193). In whole-section analyses, overall survival rates were 5.3%, 26.4%, and 43.8%, respectively ( p = 0.030). In the adjusted Cox model, whole-section ICS groups were inversely associated with the overall mortality hazard ratio (HR): low, moderate, and high ICS groups had HRs of 1.00, 0.42 (95% CI 0.20–0.88), and 0.27 (95% CI 0.11–0.67), respectively. The number of immune cells per square millimetre in the tumour core and the invasive margin were significantly higher and had a wider range in hotspots than in whole-tissue sections. Accordingly, ICS could predict survival in patients with PDAC after surgery. Whole tissue section ICSs exhibited better prognostic value than hotspot ICSs.