Peripheral absolute lymphocyte count and survival of patients with triple-negative breast cancer: a meta-analysis

Background Peripheral absolute lymphocyte count (ALC) has emerged as a potential prognostic biomarker in patients with triple-negative breast cancer (TNBC), but the available evidence remains inconsistent. We performed a systematic review and meta-analysis to evaluate the association between peripheral ALC and survival outcomes in patients with TNBC. Methods PubMed, Embase, Web of Science, Wanfang, and China National Knowledge Infrastructure (CNKI) were systematically searched from database inception to June 20, 2026. Observational studies evaluating the association between peripheral ALC and survival in adult patients with TNBC were included. Hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled using random-effects models. Results Ten studies involving 1,799 patients with TNBC were included. Low peripheral ALC was significantly associated with poorer overall survival (OS; eight studies, HR 2.22, 95% CI 1.73-2.85; I 2 = 0%) and progression-free survival (PFS; six studies, HR 2.09, 95% CI 1.61-2.72; I 2 = 4%). Subgroup analyses showed that no statistically significant subgroup differences in the association between low ALC and OS were detected according to tumor stage (stage I-III vs. stage IV), timing of ALC measurement (pretreatment vs. during treatment), method for determining the ALC cutoff (receiver operating characteristic curve analysis, median value, or predefined cutoff), ALC cutoff value (< 1.5 vs. ≥ 1.5 × 10 9 /L), follow-up duration, analytic model (univariate vs. multivariate), or study quality (all p for subgroup differences > 0.05). Conclusions Low peripheral ALC is associated with poorer OS and PFS in patients with TNBC. However, given the predominantly retrospective and geographically concentrated evidence, the potential prognostic utility of ALC requires validation in prospective studies across more diverse populations. Systematic review registration https://www.crd.york.ac.uk/prospero/ , identifier CRD420261467726.