RESUMO
OBJECTIVE: Mohs micrographic surgery (MMS) is the treatment of choice for high-risk primary basal cell carcinoma (BCC) and recurrent BCC of the head and neck, showing fewer recurrences compared with surgical excision (SE). The objectives of this study were to determine the recurrence rate of head and neck BCC after MMS and to develop a prediction model with significant risk factors for recurrence. DESIGN: A retrospective study of patient records. METHODS: All BCCs treated with MMS between 1 January 1995 and 1 July 2013 at the University Medical Center Groningen (UMCG) were selected retrospectively. Recorded parameters were patient characteristics, tumour size, tumour location, histopathological subtype, previous treatment, the number of stages until microscopic clearance, defect size, adverse events, follow-up time and recurrence after MMS. RESULTS: The study covered 1021 MMS operations conducted on primary BCCs (57.4%), residual BCCs (25.6%) and recurrent BCCs (17.0%). The median follow-up time was 54.0 months (ranging from 1 to 221 months). The 5-year cumulative probability of recurrence was 3.3%: 2.6% for primary BCCs, 5.4% for residual BCCs and 2.9% for recurrent BCCs. An aggressive histopathological subtype, residual BCCs and recurrent BCCs were significant risk factors for predicting a higher risk of recurrence after MMS. CONCLUSION: This large-scale retrospective study showed low recurrence rates after MMS for primary and recurrent BCCs. Residual BCCs treated with MMS had relatively higher recurrence rates. The risk of recurrence for MMS-treated residual aggressive BCCs was more than four times higher than that for primary non-aggressive BCCs.