Intraepithelial lymphocytes are indicators of better prognosis in surgically resected endometrioid-type endometrial carcinomas at early and advanced stages

BACKGROUND: Tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs) may be useful prognostic indicators in endometrial cancer. However, standardized assessment methods and the prognostic roles of these cells in different stage groups are unclear. METHODS: Formalin-fixed paraffin-embedded tissue samples of 107 endometrioid-type endometrial carcinomas (EECs) comprising 60 stage IB and 47 stage IIIC or IVB cases were evaluated. CD3(+) TILs, CD8(+) TILs, CD68(+) TAMs, and CD163(+) TAMs were detected by immunohistochemistry, and their densities were evaluated by semiquantitative and quantitative methods. TILs within tumor epithelial cell nests (E-TILs) and those within the stroma at the invasive front (S-TILs) were evaluated separately for CD3(+) and CD8(+) cells. The “TIL score” was defined as the sum of semiquantitative scores of CD3(+) E-TILs, CD3(+) S-TILs, CD8(+) E-TILs, and CD8(+) S-TILs. For TAMs, the area of CD68(+) and CD163(+) cells in the invasive margin were semiquantitatively and quantitatively evaluated. Clinicopathological and prognostic implications of TILs and TAMs in stage IB and IIIC/IVB EECs were examined by Cox univariate and multivariate analyses. RESULTS: By Cox univariate analyses, semiquantitatively low CD3(+) E-TILs, low CD8(+) E-TILs, and low “TIL score” were significantly correlated with worse prognosis in stage IB patients (P = 0.011, 0.040, and 0.039, respectively). Likewise, low CD3(+) E-TILs and low CD8(+) E-TILs, by both semiquantitative (P = 0.011 and 0.0051) and quantitative evaluations (P < 0.0001, and P = 0.0015) and low “TIL score” (P = 0.020) were significantly correlated with worse prognosis in stage IIIC/IVB patients. By Cox multivariate analyses, semiquantitatively low CD3(+) E-TILs and low CD8(+) E-TILs, low “TIL score”, and quantitatively low CD3(+) E-TILs and low CD8(+) E-TILs were independent worse prognostic factors in stage IIIC/IVB (P = 0.0011, 0.0053, 0.012, < 0.0001, and < 0.0001, respectively). CD68(+) or CD163(+) TAMs were not correlated with prognosis in any patients. CONCLUSIONS: Both semiquantitatively and quantitatively low E-TILs, are correlated with worse prognosis in both early and advanced stage patients with EECs. In particular, CD3(+) E-TILs and CD8(+) E-TILs are potentially useful prognostic markers in patients with EEC regardless of the stage. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12885-022-09363-0.