CD45RO-Positive Memory T-Cell Density in the Tumoral Core and Invasive Margin Predict Long-Term Survival in Esophageal Squamous Cell Carcinoma

Background: The association between tumor-infiltrating lymphocytes and tumor immunity has long been recognized. Among T-cell types, CD45RO-positive memory T cells (CD45RO⁺) are reported to correlate with survival in several cancer types, but clinical evidence is lacking in esophageal squamous cell carcinoma (ESCC).

Methods: In surgical specimens from 162 preoperatively untreated patients, immunohistochemistry for CD45RO was performed to evaluate the density of CD45RO⁺ in the tumor core (CT) and invasive margin (IM) using an auto-count method. Patients were classified into high- versus low-CD45RO⁺ groups based on CD45RO⁺ density in CT and IM separately and combined. The relationship between CD45RO⁺ density and clinicopathological factors, including prognosis, was evaluated.

Results: Average CD45RO⁺ density was 133/mm² in CT and 372/mm² in IM. No significant differences in clinicopathological factors according to high- versus low-CD45RO⁺ scores were identified. Using CT scores, the CD45RO⁺-high group had a better 5-year overall survival (OS) rate (77.2% vs. 54.7% CD45RO⁺-low, P = 0.0433), but OS rates did not differ statistically between the two groups by IM scores (75.7% vs. 50.3%, P = 0.0576). Using immunohistochemical scores for CT+IM, the survival difference was significant, with a 5-year OS rate of 73.7% for the CD45RO⁺-high group versus 46.3% for the CD45RO⁺-low group (P = 0.0141). Multivariate analysis identified CD45RO⁺ CT+IM density as an independent prognostic variable in OS (hazard ratio 2.27, 95% confidence interval 1.43-3.62, P = 0.0006).

Conclusions: Density of CD45RO⁺ expression in the CT and IM might be a predictor of long-term survival in ESCC.