Calreticulin and heat shock protein 70 expression, immune infiltration, and prognostic stratification in endometrial...

Accessible biomarkers are needed to complement conventional clinicopathological risk assessment in endometrial cancer. Calreticulin (CALR) and heat shock protein 70 (HSP70) are stress-related proteins involved in immunogenic cell death and tumor-immune interactions, but their clinicopathological and prognostic relevance remains unclear.

This retrospective cohort included 286 surgically treated patients who underwent surgery between January 2016 and December 2023, with administrative follow-up through December 31, 2025. CALR and HSP70 expression was assessed by immunohistochemistry and classified as low or high using prespecified semiquantitative thresholds. CD8+ and CD68+ cell densities were evaluated as immune infiltration markers. Associations with adverse pathological features were examined using logistic regression with false-discovery rate correction. Recurrence-free survival (RFS), defined as recurrence or death, and overall survival (OS) were analyzed using Kaplan-Meier curves and Cox regression. Clinical and integrated models were compared for 3-year recurrence prediction with bootstrap validation.

High CALR and high HSP70 expression were independently associated with grade 3 disease, deep myometrial invasion, lymphovascular space invasion, lymph node metastasis, advanced clinicopathological stage, and a secondary adverse pathology summary endpoint after false-discovery rate correction. High expression of either marker was associated with lower CD8+ and higher CD68+ density. In multivariable RFS models including adjuvant treatment, HSP70-high expression remained associated with poorer RFS (adjusted HR 1.85, 95% CI 1.23-2.79; P = 0.003), whereas CALR-high expression did not. The CALR-high/HSP70-high phenotype was also associated with poorer RFS (adjusted HR 2.30, 95% CI 1.36-3.88; P = 0.002). OS models were exploratory because of limited deaths, although associations for HSP70-high expression and the double-high phenotype were directionally consistent. For 3-year recurrence prediction, the integrated model showed a small apparent AUC increase over the clinical model (0.779 vs. 0.763; DeLong P = 0.350), which was not retained after bootstrap optimism correction (0.717 vs. 0.720).

CALR and HSP70 expression were associated with aggressive pathology and an immune profile characterized by reduced CD8+ and increased CD68+ infiltration. HSP70 and the CALR-high/HSP70-high phenotype showed the most consistent RFS associations, whereas OS and prediction-model findings require cautious interpretation.