BackgroundTo evaluate the association of primary tumor size with clinicopathologic characteristics and survival of patients with squamous cell carcinoma of the penis (SCCP).MethodsThis study analyzed the data of 1001 patients with SCCP, obtained from the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2014. The Kaplan–Meier method and the Cox proportional hazards regression model were used to analyze the effects of primary tumor size on overall survival (OS) and penile carcinoma-specific survival (PCSS).ResultsAdvanced T stage (P < 0.001), lymph node metastasis (P < 0.001) and distant metastasis (P = 0.001) were more frequently associated with SCCP patients with tumor size ≥ 3 cm than those with tumor size < 3 cm. In Kaplan–Meier analyses, the patients with large tumors (≥ 3 cm) exhibited an inferior OS and PCSS than those with small tumors (< 3 cm). Moreover, tumor size was identified to be an independent prognostic factor for OS [hazard ratio (HR) 1.665, P < 0.001] and PCSS (HR 2.076, P = 0.003) of patients with SCCP in multivariate analyses.ConclusionsLarge tumor size is associated with adverse clinicopathological characteristics of patients with SCCP. Besides, tumor size represents an independent prognostic factor for OS and PCSS. Therefore, clinical assessment of tumor size as a crucial prognostic factor might be highly beneficial for early intervention in patients with SCCP.