Tumor-infiltrating lymphocytes (TILs) have long been recognized as playing an important role in tumor immune microenvironment. Lately, the Immunoscore (IS) has been proposed as a new method of quantifying the number of TILs in association with patient survival in several cancer types.
In 300 preoperatively untreated esophageal cancer (EC) patients who underwent curative resection at two different institutes, immunohistochemical staining using CD3 and CD8 antibodies was performed to evaluate IS, as objectively scored by auto-counted TILs in the tumor core and invasive margin. In addition, in pre-neoadjuvant chemotherapy (pre-NAC) endoscopic biopsies of a different cohort of 146 EC patients who received NAC, CD3 and CD8 were immunostained to evaluate TIL density.
In all cases, the IS-high (score 3–4) group tended to have better survival (5-year overall survival [OS] of the IS-high vs low group: 77.6 vs 65.8%, P = 0.0722) than the IS-low (score 1–2) group. This trend was more remarkable in cStage II–IV patients (70.2 vs 54.5%, P = 0.0208) and multivariate analysis of OS further identified IS (hazard ratio 2.07, P = 0.0043) to be an independent prognostic variable. In preNAC biopsies, NAC-responders had higher densities than non-responders of both CD3+ (P = 0.0106) and CD8+ cells (P = 0.0729) and, particularly CD3+ cell density was found to be an independent prognostic factor (hazard ratio 1.75, P = 0.0169).
The IS signature in surgical specimens and TIL density in preNAC-biopsies could be predictive markers of clinical outcomes in EC patients.