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

Importance The currently recommended postoperative adjuvant treatment for sinonasal mucosal melanoma (SNMM) (chemotherapy, optionally accompanied by local radiotherapy) has limited efficacy. Objective We aimed to provide a potentially optimal adjuvant therapeutic strategy for patients with SNMM. Design Retrospective cohort study. Setting Our hospital’s cancer center. Participants Seventy-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. Interventions Patients 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 measures These included recurrence-free survival (RFS), distant metastasis-free survival (DMFS), failure patterns, and overall survival (OS). Results The 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; P = .002), DMFS (mDMFS: 11.2 months vs 18.9 months; HR, 0.48; 95% CI, 0.27-0.84; P = .009), and OS (29.1 months vs NA; HR, 0.36; 95% CI, 0.17-0.77; P = .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%, P < .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 relevance Surgery followed by adjuvant chemoradiotherapy and prompt initiation of PD-1 inhibitor therapy may improve local disease control in patients with SNMM.