Recurrence of Basal Cell Carcinoma across Different Treatment Modalities: A Nationwide Study with 8 Years of Follow-up and Modelled Prediction.

Despite the rising incidence of basal cell carcinoma (BCC), few studies have compared treatment outcomes or predicted recurrences using nationwide real-world datasets. Hence, the objective was to investigate and compare recurrence rates of nodular BCC (nBCC) and superficial BCC (sBCC) following treatment with standard excision (SE), curettage, cryotherapy, photodynamic therapy and imiquimod. Additionally, we identified predictors of BCC 2 year recurrence using machine-learning. The study examined BCCs treated in state-funded, office-based dermatology practices registered in the Danish Skin Cancer Registry from 2014 to 2024. A total of 131,119 tumours were included, comprising 100,221 nBCCs and 30,898 sBCCs. For nBCC, the lowest rate of recurrence was observed for SE, with an 8-year cumulative recurrence rate (CRR) of 16.5% (95% confidence interval: 14.4-19.0%) and hazard ratio of 0.80 (0.76-0.84) compared with curettage. For sBCC, both SE and curettage had similarly low 8 year CRRs of 16.3% (12.7-20.8%) and 16.3% (15.2 17.5%), respectively, with no significant difference in hazard. The machine-learning model identified key predictors of BCC recurrence, including facial location, larger tumour size, having a high number of hospital-registered diagnoses and short distance to dermatological clinics. These findings highlight the impact of treatment selection and patient-specific factors in guiding dermatologists towards optimal BCC management.