Objective We investigated the density of infiltrating CD163⁺ (cluster of differentiation 163, CD163) M2-type macrophages in esophageal squamous cell carcinoma (ESCC) during radiotherapy and their correlation with therapeutic efficacy.

Methods We employed bioinformatic methods to analyze M2-type macrophage infiltration into ESCC. Clinical data and pathological tissue samples were collected from 56 patients with ESCC treated at The First Affiliated Hospital of Xinjiang Medical University between January 2014 to December 2024. Based on treatment response, these patients were assigned into radiotherapy-sensitive and radiotherapy-resistant groups. Densities of infiltrating CD163⁺ M2 macrophages were detected by immunohistochemistry (IHC). Univariate Logistic regression, chi-square analysis, and other statistical methods were used to assess for correlation between radiotherapy efficacy and M2 macrophage infiltration. ROC curves were plotted to evaluate the value of CD163⁺ M2 macrophage presence as a sensitivity predictor.

Results Bioinformatic analysis revealed high M2 macrophage infiltrationin ESCC. IHC results showed significantly elevated levels of CD163⁺ M2 macrophages in radiotherapy-resistant tissues. Univariate Logistic regression analysis identified distant metastasis and macrophage infiltration as risk factors affecting short-term radiotherapy efficacy (P<0.05). Chi-square analysis revealed that infiltrating M2 macrophage density significantly correlated with radiotherapy sensitivity, distant metastasis, and clinical stage (P<0.05). Area under the ROC curve (AUC) was 0.705, indicating its predictive value.

Conclusions High CD163⁺ M2 macrophage infiltration in patients with esophageal cancer suggests a close correlation with cancer progression and demonstrates significant clinical value in short-term efficacy evaluation.