Evaluation of Radiotherapy After Complete Response to Sonic Hedgehog Pathway Inhibitors in Patients With Locally Advanced Basal Cell Carcinoma: a Prospective Multicenter Study

Locally advanced basal cell carcinoma (BCC) are large BCCs or BCCs located in areas subject to functional and aesthetic risk following surgery or radiotherapy. In these particular situations, surgery and radiotherapy are sometimes not appropriate, and Sonic Hedgehog inhibitors (SHHi) (Vismodegib and Sonidegib) can be proposed. SHHi are effective treatments in laBCC but most CR patients discontinue treatment because of tolerability. Approximately 65% of the population experience a relapse after discontinuation. A few cases of patients treated concomitantly by radiotherapy and vismodegib have been reported in the literature, suggesting that combining vismodegib and concomitant radiotherapy results in an improved overall response compared to a single modality treatment. There is no study evaluating a "consolidation radiotherapy" after complete response to SHHi. We carry out a prospective multicenter study in order to evaluate consolidation radiotherapy in patients with laBCC after achieving complete response with SHHi, with the hypothesis of reducing recurrence after discontinuation of SHHi.