Merkel cell carcinoma: A retrospective analysis of urban vs. rural survival outcomes from the United States’ National Cancer Institute, a SEER based study

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine malignancy with poor survival outcomes, particularly among patients with barriers to timely care. Rural populations may experience delayed diagnosis and treatment due to geographic, socioeconomic, and healthcare access disparities. A retrospective cohort study was performed using the Surveillance, Epidemiology, and End Results (SEER) database (2010–2021). Adults aged 25–90 years with a confirmed MCC diagnosis were included classified by Rural–Urban Continuum Codes (RUCC): metropolitan counties (RUCC 1–3) and rural counties (RUCC 4–9). MCC-specific survival was evaluated using Kaplan–Meier analysis and compared using the log-rank test. Descriptive statistics were used to compare baseline characteristics. A total of 2,357 patients were identified; most were elderly, white, and male. 1,965 (83.4%) resided in metropolitan counties and 392 (16.6%) in rural counties. Rural patients demonstrated lower county-level median household incomes compared with metropolitan residents. MCC-specific deaths occurred in 429 (21.8%) metropolitan residents and 102 (26.0%) rural residents. Five-year MCC-specific survival was 71.6% among metropolitan residents versus 65.6% among rural residents, (log-rank p=0.064). Five-year cumulative survival was 51.3% among metropolitan residents compared with 46.0% among rural residents, with Kaplan-Meier curves showing a statistically significant divergence (log-rank p < 0.05). Using an RUCC-based definition of rurality (RUCC 4–9), rural residence was associated with a lower 5-year MCC-specific survival and worse cumulative 5-year survival. Although the difference among MCC-specific survival did not reach conventional statistical significance, this disparity may be clinically meaningful and warrants further investigation using adjusted models.