Adjuvant radiotherapy in sinonasal mucosal melanoma

Objectives: Evaluation of outcome after curative treatment for sinonasal mucosal melanoma focused on the effect of adjuvant radiotherapy on recurrence and survival. Design: Retrospective chart analysis. Setting: Tertiary referral hospital. Participants: Fifty-one patients with primary sinonasal mucosal melanoma who underwent surgical resection with curative intention between 1980 and 2016 at Erasmus Medical Center, Rotterdam.
Main outcome measures: Patients were categorised into 2 groups: surgery alone and surgery with adjuvant radiotherapy. Log-rank test was used to compare rates of recurrence and survival between treatment groups. Predictors for treatment modality, recurrence and survival were assessed with multivariate statistical analysis.
Results: Of all patients, 23.5% developed local recurrence and 47.1% developed distant metastasis. Estimated 5-year disease-free survival was 25.2%, and 5-year overall survival (OS) was 38.1%. Forty-three patients (84.3%) were treated with post-operative radiotherapy. Patients who underwent surgery with adjuvant radiotherapy presented more often with high tumour stage, tumour involving multiple sites and positive margins. Post-operative radiotherapy seemed to be associated with better local control (P =.549). No effect was found on occurrence of distant metastasis and OS. Positive margin status was an independent negative predictor for distant metastasis-free survival and overall survival.
Conclusions: Our treatment outcomes are consistent with literature. Post-operative radiotherapy seems to be associated with improved local control despite advanced disease and positive margin status in this treatment group.