Prognostic impact of tumour-associated B cells and plasma cells in oesophageal and gastric adenocarcinoma

Background: While it is well established that the cell-mediated immune response plays an important role in cancer progression and spread, the role of the humoral immune response in this regard has been less studied. According to the existing literature, dense infiltration of B cells or plasma cells appears to correlate mainly with an improved prognosis in several types of cancer, but their prognostic impact in oesophageal and gastric cancer has not yet been described. Methods: Immunohistochemistry was applied on tissue microarrays (TMA) to assess the stromal density of B cells (CD20+) and plasma cells [CD138+ or immunoglobulin kappa C (IGKC+)] in chemo-/radiotherapy-naive tumours from a consecutive cohort of 174 patients with resected oesophageal or gastric adenocarcinoma. Cox proportional hazard's modelling was applied to examine the impact of the investigated markers on overall survival (OS) and time to recurrence (TTR). Results: In curatively treated patients with oesophageal adenocarcinoma, high expression of IGKC was an independent predictor of a prolonged OS [hazard ratio (HR) 0.10; 95% confidence interval (CI), 0.02-0.57], and TTR (HR 0.15; 95% CI, 0.03-0.71). In curatively treated patients with gastric adenocarcinoma, high expression of IGKC independently predicted a prolonged OS (HR 0.46; 95 % CI, 0.24-0.87) and TTR (HR 0.46; 95% CI, 0.21-0.98). Expression of CD20 was not prognostic, and CD138 expression was only prognostic in unadjusted analysis of TTR in gastric cancer. Conclusions: These results demonstrate, for the first time, that abundant infiltration of IGKC+ plasma cells independently predicts a prolonged survival in both oesophageal and gastric cancer.