Absolute Lymphocyte Count as an Independent Prognostic Factor in Metastatic Breast Cancer: A Retrospective Study.

Introduction: Recently, absolute lymphocyte count (ALC) and neutrophil-to-lymphocyte ratio (NLR) have been reported to be prognostic and/or predictive factors in breast cancer. However, most of the investigations on the relationship between systemic inflammatory markers and prognosis have been conducted perioperatively, with few studies reporting on patients with metastatic or recurrent breast cancer (MBC). Here, we investigated the role of ALC and NLR as prognostic factors of MBC.

Methods: This was a retrospective observational study of patients with MBC treated at the University of Tsukuba Hospital between 2013 and 2020. ALC and NLR clinical data were obtained from the patients' charts. Based on the previous reports, the cutoff value of ALC was set at 1,500/µL and that of NLR, at 3. We investigated the prognostic significance of ALC and NLR.

Results: About 80% of the 243 included patients were hormone receptor-positive, 20% were HER2-positive, and 10% were triple negative. The patients were grouped as follows: 114 (46.9%) and 129 (53.1%) in the high and low ALC groups and 145 (59.7%) and 98 (40.3%) in the high and low NLR groups, respectively. The group with high ALC at diagnosis of MBC showed significantly better prognosis (p = 0.002), and the median overall survival (OS) was 70.9 months, as compared with 40.2 months for the low ALC group. On multivariate analysis, visceral metastasis, subtype, and ALC were independent variables for OS; the NLR status was not correlated with OS.

Conclusions: Analysis of real-world data suggests that ALC at diagnosis of MBC is an independent prognostic factor.