Combination of Postoperative Adjuvant Chemoradiotherapy and Immune Checkpoint Inhibitors Significantly Prolongs Recurrence-Free Survival in Sinonasal Mucosal Melanoma.

ImportanceThe currently recommended postoperative adjuvant treatment for sinonasal mucosal melanoma (SNMM) (chemotherapy, optionally accompanied by local radiotherapy) has limited efficacy.ObjectiveWe aimed to provide a potentially optimal adjuvant therapeutic strategy for patients with SNMM.DesignRetrospective cohort study.SettingOur hospital's cancer center.ParticipantsSeventy-nine patients with stage III/IV SNMM who underwent complete resection and received adjuvant radiotherapy between April 2012 and October 2022 were included in the study.InterventionsPatients were categorized into 2 groups based on different adjuvant medical regimens: a temozolomide/dacarbazine-based chemotherapy group (n = 44) and a temozolomide/dacarbazine chemotherapy plus PD-1 inhibitor group (n = 35).Main outcome measuresThese included recurrence-free survival (RFS), distant metastasis-free survival (DMFS), failure patterns, and overall survival (OS).ResultsThe median follow-up duration was 56.8 (8.85-104.75) months in the chemotherapy group and 27.7 (14.53-40.87) months in the chemotherapy plus PD-1 inhibitor group, respectively. Relative to adjuvant chemoradiotherapy, the combination of additional PD-1 inhibitor significantly prolonged RFS (mRFS: 10.0 months vs 18.9 months; HR, 0.43; 95% CI, 0.25-0.75;  = .002), DMFS (mDMFS: 11.2 months vs 18.9 months; HR, 0.48; 95% CI, 0.27-0.84;  = .009), and OS (29.1 months vs NA; HR, 0.36; 95% CI, 0.17-0.77;  = .006) in patients with SNMM. Within a 2-year timeframe, patients in the chemotherapy plus PD-1 inhibitor group exhibited a lower regional recurrence rate than those in the chemotherapy group (0.0% vs 18.8%,  < .001). The 2-year OS rates in the adjuvant chemotherapy group and the chemotherapy combined with PD-1 inhibitor group were 54.5% versus 75.7%, respectively, while the corresponding 4-year OS rates were 20.9% and 62.4%.Conclusions and relevanceSurgery followed by adjuvant chemoradiotherapy and prompt initiation of PD-1 inhibitor therapy may improve local disease control in patients with SNMM.