Supplementary Material for: Survival outcomes of Mohs surgery versus wide local excision for less common nonmelanoma skin cancers: A stabilized inverse probability of treatment weighting analysis

Objectives: To compare the survival outcomes of Mohs micrographic surgery (MMS) and wide local excision (WLE) for less common nonmelanoma skin cancers (NMSCs). Methods: This study retrospectively analyzed data from the Surveillance, Epidemiology, and End Results dataset between 2003 and 2018. The less common NMSCs include Merkel cell carcinoma, skin appendage neoplasm, fibromatous malignancy, and other rare NMSCs. The stabilized inverse probability of treatment weighting (SIPTW) and the Kaplan–Meier methods were adopted to assess the overall survival (OS) and cancer-specific survival (CSS). Furthermore, the Cox proportional hazards, Fine-and-Gray regression analysis, and subgroup analysis models were applied to examine the effects of MMS vs. WLE based on all-cause and cancer-specific mortality. Results: We identified 6582 individuals with less common NMSCs for survival analysis, among which 1946 patients (29.5%) had undergone MMS and 4636 (70.5%) had received WLE. Diseases diagnosed in the most recent year, older age, the White race, married status, eyelid/face site, small tumor size, and localized disease were factors significantly associated with MMS treatment. Compared with the WLE group, the MMS group had comparable OS before and after the SIPTW analysis. Additionally, after adjusting for other confounding covariates, the surgery type (WLE vs. MMS) did not show significant associations with all-cause mortality (hazard ratio [HR]: 1.03, 95% confidence interval [CI]: 0.94–1.14, P = 0.517) and disease-specific mortality (HR: 1.16, 95% CI: 0.95–1.42, P = 0.134). Moreover, the subgroup analysis validated these findings. Conclusion: MMS and WLE have comparable OS and CSS for less common NMSCs.