Tumor-infiltrating plasma cells are the promising prognosis marker for esophageal squamous cell carcinoma.

Background: There is an urgent need to improve the clinical and basic research of esophageal cancer. The purpose of this study was to explore the prognostic value of tumor-infiltrating plasma cells (TIP) on overall survival (OS) of patients with esophageal squamous cell carcinoma (ESCC).

Methods: Three independent cohorts, which include 116 consecutive cases who received radical resection of ESCC in our institution (set to be discovery set), 179 cases from public GEO database (validation GEO set) and 95 cases from TCGA (validation TCGA set), with a total of 390 cases were retrospectively enrolled in this study.

Results: TIP was detected by immunohistochemical staining of CD138 in the paraffin-embedded specimen after surgery in the discovery set and was validated by using an established computational algorithm in the GEO and TCGA sets. Kaplan-Meier survival analysis showed high TIP was coincidently and significantly associated with favorable OS of ESCC in discovery set (p = 0.004) and validation GEO set (p = 0.002), showed a trend of better survival in validation TCGA set (p = 0.256 for 5-year OS, p = 0.034 for 15-month OS). Univariate and multivariate Cox regression analysis, together with survival analysis of the interaction between TIP and other variables, confirmed TIP to be a significant and independent prognostic factor for OS of ESCC. The incorporation of TIP into the TNM staging system could improve the accuracy of prognosis prediction for ESCC.

Conclusion: This study revealed that high TIP in ESCC was associated with positive regulation of adaptive immunity and anti-tumor activity.