Predicting the prognosis of breast cancer patients by using nutrition-based index: a systematic review and...

The prognostic nutritional index (PNI) and the controlling nutritional status (CONUT) score are composite markers of nutritional and inflammatory status that are used to predict tumor progression. Their prognostic relevance in breast cancer (BC) has been reported, but the evidence remains inconsistent. Therefore, the prognostic utility of PNI and CONUT in BC was evaluated in this meta-analysis.

A search was carried out across four major databases: PubMed, Embase, Web of Science, and the Cochrane Library, from inception to 20 October 2025. Studies assessing the association of PNI or CONUT with clinical outcomes in BC were included based on prespecified eligibility criteria. Overall survival (OS), disease-free survival (DFS), and pathological complete response (pCR) were analyzed, and pooled effects were reported as hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs). Subgroup analyses, meta-regression, and 95% prediction intervals (PIs) were used to explore heterogeneity.

A total of 32 reports comprising 13,120 individuals with BC were included. Higher PNI was linked with improved OS (HR = 0.49, 95% CI 0.39-0.61; P < 0.00001; I² = 83%) and longer DFS (HR = 0.69, 95% CI 0.58-0.81; P < 0.00001; I² = 83%), whereas the evidence for an association between PNI and pCR was inconclusive (OR = 1.57, 95% CI 1.00-2.47; P = 0.05; I² = 83%), and the result was sensitive to individual studies. In addition, higher CONUT corresponded to poorer OS (HR = 1.77, 95% CI 1.29-2.44; P = 0.0005; I² = 77%) and shorter DFS (HR = 2.08, 95% CI 1.75-2.47; P < 0.00001; I² = 6%). Prediction intervals for PNI and OS, PNI and DFS, PNI and pCR, and CONUT and OS all crossed the null value, indicating substantial between-study variability in the expected effect across future settings.

Across the included studies, higher PNI was associated with better OS and DFS, while elevated CONUT was associated with poorer OS and DFS. Therefore, PNI and CONUT may be considered candidate prognostic indicators in BC.Systematic review registration: PROSPERO, identifier CRD420251249070.