Prognostic factors associated with overall survival in patients with Merkel cell carcinoma: A retrospective analysis in a Mexican cohort at a tertiary referral center in Latin America.

Abstract

e21571 Background: Merkel cell carcinoma is a rare but highly aggressive neuroendocrine neoplasm of the skin. It predominantly affects older people and immunocompromised individuals. Furthermore, it is known for its high risk of recurrence and metastatic potential. This retrospective cohort aims to identify clinical, pathologic, and therapeutic variables as prognostic factors associated with overall survival. Methods: Demographics, clinical and pathological features, treatment modality, progression, and functional status were recorded. Associations with mortality were assessed using contingency analyses (χ2/Fisher). Survival analysis was estimated using Kaplan–Meier with log-rank testing for PFS and OS. Cox proportional hazards models produced univariate and multivariable hazard ratios. Results: In this retrospective cohort of 63 patients, the median age was 70 years (IQR 62–80). Stages I–IV comprised 15.9%, 20.6%, 30.2%, and 33.3%, respectively. Forty-five patients (71.4%) were alive, and 18 (28.6%) were deceased; progression occurred in 22 (34.9%). Contingency analyses linked mortality to metastasis (p < 0.001), ECOG (p = 0.001), clinical stage (p < 0.001), tumor border status (p < 0.001), symptoms (p = 0.037), superinfection (p = 0.005), and receipt of institutional systemic therapy (p = 0.021). Univariate Cox findings included progression HR 7.00 (95% CI 2.09–23.38; p = 0.002), metastatic disease HR 32.5 (95% CI 7.19–146.89; p < 0.001), ECOG ≥2 HR 8.20 (95% CI 2.05–32.76; p = 0.003), and stage IV HR 22.5 (95% CI 2.32–218.35; p = 0.007). Defined surgical margins were protective (HR 0.098; 95% CI 0.027–0.352; p < 0.001). Receipt of extra-institutional treatment correlated with a higher unadjusted hazard (HR 3.9; 95% CI 1.18–12.83; p = 0.025). Multivariable Cox regression retained progression as an independent predictor of reduced OS (adjusted HR 4.76; 95% CI 1.16–19.58; p = 0.030); metastasis showed a strong trend after adjustment (adjusted HR 9.41; 95% CI 0.94–94.10; p = 0.056). Median PFS was 17.0 months (95% CI 0.0–47.9), and median OS was 39.0 months (95% CI 16.7–61.3); metastatic patients had markedly inferior OS (median 7.0 months vs NR for M0; p < 0.001), and age > 55 years was associated with shorter OS (median 39.0 vs 113.0 months; p = 0.033). Conclusions: Progression was the principal independent determinant of survival. Metastatic disease, poor performance status, and advanced stage strongly predicted mortality in univariate analyses; the limited sample size likely constrained detection of additional independent effects. Clear surgical margins were associated with improved unadjusted survival, underscoring the importance of early control and accurate staging.