Baseline Red Blood Cell Distribution Width as a Prognostic Marker in High-Risk Resected Cutaneous Melanoma

<b>Background and Objectives:</b> High-risk resected cutaneous melanoma carries a substantial risk of recurrence, and additional host-related prognostic biomarkers are needed beyond conventional tumor-centered factors. Red blood cell distribution width (RDW) reflects systemic inflammation and physiological stress and may provide incremental prognostic information. <b>Materials and Methods:</b> In this retrospective cohort study, 164 patients with stage II-III cutaneous melanoma who underwent curative-intent surgical resection were analyzed. A receiver operating characteristic (ROC) curve analysis determined the optimal RDW cut-off for relapse-free survival (RFS), which was 14.2%. Patients were categorized into low and high RDW groups accordingly. Survival probabilities were estimated using the Kaplan-Meier method and compared with the log-rank test. Univariate and multivariate Cox proportional hazards regression models were used to evaluate associations between RDW status, clinicopathological variables, and RFS. <b>Results:</b> During a median follow-up of 58.3 months, patients with high RDW had significantly shorter RFS compared with those with low RDW. In univariate analysis, elevated RDW was associated with an increased risk of recurrence (HR 2.79, 95% CI 1.39-5.58; <i>p</i> = 0.004). After adjustment for key prognostic factors (e.g., stage, Breslow, age, adjuvant therapy), high RDW remained an independent predictor of inferior RFS (HR 2.74, 95% CI 1.37-5.47; <i>p</i> = 0.004). Stage III disease also independently predicted worse RFS (HR 4.67, 95% CI 2.04-10.68; <i>p</i> < 0.001). <b>Conclusions:</b> Baseline RDW independently predicts RFS in high-risk resected stage II-III cutaneous melanoma and may enhance prognostic stratification using a simple, widely available biomarker.