Lymphocyte-to-monocyte ratio predicts survival in localized osteosarcoma in Vietnamese patients.

Inflammatory markers such as the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR), alongside hemoglobin (Hgb) levels, have been proposed as prognostic tools in osteosarcoma, though their reliability remains unclear. We retrospectively evaluated the prognostic significance of these pre-operative markers in a cohort of 100 Vietnamese patients with stage IB-IIB osteosarcoma, specifically focusing on the post-neoadjuvant, pre-operative window, a clinically critical yet underexplored time frame. In the primary dichotomized multivariable analysis, LMR emerged as an independent predictor of poor overall survival, whereas PLR showed only univariable associations, and NLR and Hgb were not statistically significant. While LMR demonstrated robust prognostic value for overall survival, it failed to predict disease progression within 24 months. To address cutpoint bias, sensitivity analyses modeling these markers as continuous variables combined with internal bootstrap validation (1000 resamples) confirmed parameter stability only for LMR, but not PLR and NLR. Reflecting these continuous trends, the final multivariable model achieved an apparent C-index of 0.729, which adjusted to an optimism-corrected C-index of 0.628. External literature-derived median cutoffs did not show significant associations when applied to this post-neoadjuvant cohort, highlighting key population- and timing-specific limitations. Although these peripheral blood markers demonstrate prognostic potential, our findings remain exploratory, and validation in independent multi-center cohorts with longitudinal prospective evaluation is required before their clinical utility can be established.