Prognostic value of pre-treatment serum CA19-9 and lymphocyte-to-monocyte ratio in HR+/HER2- breast cancer: a retrospective cohort study

The prognostic significance of carbohydrate antigen 19 − 9 (CA19-9) and the lymphocyte-to-monocyte ratio (LMR) in hormone receptor–positive/human epidermal growth factor receptor 2–negative (HR+/HER2-) breast cancer remains unclear. This study aimed to evaluate their value as pre-treatment prognostic markers. We retrospectively analyzed 349 h+/HER2- breast cancer patients who underwent surgery between 2011 and 2012. Patients with other malignancies or incomplete follow-up were excluded. Serum CA19-9 levels and LMR were measured before any treatment, and optimal cut-offs were determined using receiver operating characteristic (ROC) curves. ROC analysis identified cut-offs of 27.54 U/mL for CA19-9 and 5.34 for LMR. Patients with CA19-9 ≤ 27.54 U/mL had significantly longer OS, and patients with LMR > 5.34 also had significantly longer OS (P = 0.019 and P = 0.021, respectively). Multivariate Cox analysis identified N stage and high pre-treatment CA19-9 as independent predictors of OS, whereas LMR, age, tumor grade, Ki-67, menopausal status, and tumor size were not independently associated with OS. A combined risk score incorporating CA19-9 and LMR was associated with OS stratification within this cohort, with the low-risk group showing more favorable OS (P < 0.05). Nomogram analysis integrating CA19-9, LMR, and clinicopathologic factors showed moderate discrimination in internal validation. High pre-treatment CA19-9 was independently associated with worse overall survival, whereas the prognostic value of LMR was limited to univariate analysis. The combined assessment of CA19-9 and LMR may provide supplementary prognostic information, although its incremental value beyond established clinicopathologic factors appears limited and requires further validation in independent cohorts.