Clinical and Histological Predictors of Advanced Basal Cell Carcinoma Recurrence After Complete Response to Hedgehog Pathway Inhibitors: A Retrospective Multicenter Observational Study

Background/Objectives: Long-term outcome data of locally advanced basal cell carcinoma patients who achieve complete response (CR) on hedgehog pathway inhibitors (HHIs) are lacking, highlighting a gap in the identification of the predictors of tumor recurrence. We aimed to investigate the clinical and histological factors associated with locally advanced BCC recurrence after CR on HHIs. Patients and methods: We performed a retrospective multicenter observational study at 14 Italian tertiary referral centers (1 January 2016–1 March 2024). Univariate logistic regression was used to investigate the association between locally advanced BCC recurrence and clinical and histological features. Kaplan–Meier analysis was used to estimate relapse-free survival (RFS). Results: A total of 106 locally advanced BCC patients were enrolled, of whom 14/106 (13.2%) experienced relapse after a median follow-up of 12 months (range: 1–70 months). Low-risk locally advanced BCC histological subtypes (superficial and nodular) were associated with a decreased probability of locally advanced BCC recurrence (odds ratio [OR]: 0.15, 95% CI: 0.04–0.51; p: 0.003); a longer time to CR predicted locally advanced BCC relapse (OR: 1.07, 95% CI: 1.01–1.15; p: 0.04). Accordingly, locally advanced BCC histology and time to CR significantly impacted RFS probability. Conclusions: Specific locally advanced BCC histological subtypes and time to CR predict tumor recurrence after CR on HHIs.