Diagnostic performance of systemic inflammatory and nutritional indices and their association with clinicopathological features in endometrial cancer: a retrospective study

BACKGROUND: Systemic inflammatory and nutritional indices derived from routine blood tests have been widely investigated as prognostic markers; however, their diagnostic value in differentiating benign endometrial disease from endometrial cancer (EC) remains insufficiently defined. This study aimed to evaluate the diagnostic performance of inflammatory and nutritional indices and to explore their associations with clinicopathological features in EC. METHODS: This retrospective observational study included 270 patients who underwent surgical evaluation for endometrial pathology. The cohort comprised 135 patients with histopathologically confirmed endometrial cancer and 135 patients with benign endometrial conditions. Preoperative inflammatory indices, including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), and prognostic nutritional index (PNI), were calculated. Clinicopathological characteristics and immunohistochemical findings were recorded. Multivariable logistic regression analysis was performed to identify independent predictors of malignancy. RESULTS: All inflammatory indices and PNI were significantly higher in the malignant group (all p < 0.001). In multivariable analysis, age, body mass index, haemoglobin level, SII (OR = 1.004, 95% CI 1.001-1.007; p = 0.018), and PNI (OR = 1.380, 95% CI 1.228-1.550; p < 0.001) emerged as independent predictors of malignancy. Receiver operating characteristic (ROC) analysis showed that PNI had limited discriminative ability (area under the curve [AUC] = 0.620, 95% CI 0.554-0.687), with a cut-off value of 52.0 (sensitivity 69.6%, specificity 50.4%). Within the malignant cohort, lower PNI values were significantly associated with adverse clinicopathological features, including deep myometrial invasion, cervical stromal invasion, lymph node metastasis, higher tumour grade, serous histology, and abnormal p53 expression. CONCLUSIONS: Systemic inflammatory and nutritional indices may provide complementary information in the evaluation of endometrial pathology. While SII appears to be associated with malignancy risk, PNI primarily reflects tumour aggressiveness rather than diagnostic discrimination. These readily available biomarkers may support preoperative risk stratification, particularly in patients with inconclusive imaging or biopsy results, where additional risk stratification may help guide the urgency or extent of surgical planning; however, further prospective studies are required to confirm their clinical utility.