1126P - REtrospective Study of definitive therapy for head and neck mUcosal MElanoma: The RESUME study

Background

Head and neck mucosal melanoma (HNMM) is a rare clinical subtype of melanoma. The aim of this study was to compare survival following surgery-based treatment (S group) versus radiotherapy-based treatment (RT group) and to assess the efficacy of the addition of adjuvant immune checkpoint inhibitor (adj-ICI) after definitive treatment for locally advanced HNMM patients.

Methods

This was a multi-institutional retrospective study which enrolled patients treated for locally advanced HNMM patients between October 2014 and March 2022. Treatment efficacy was compared between the S and RT groups and between those with and without adj-ICI.

Results

Among 294 patients, 148 patients were in the S group and 146 in the RT group. In the RT group, 80 patients received proton RT and 43 received carbon ion RT. Patient characteristics between the S and RT groups were mostly similar, except for patients with nasal and paranasal sinus primary sites (77% in S group vs. 91% in RT group) and clinical-T4 stage disease (25% in S group vs. 51% in RT group). Overall, 29 in the S group and 43 in the RT group received adj-ICI. Among patients without adj-ICI, the S group tend to have longer progression-free survival (PFS) than the RT group (hazard ratio [HR] 1.34, 95% confidence interval [CI] 0.98-1.84). However, there was no significant difference in overall survival (OS) between the S and RT groups (HR 1.02, 95% CI 0.64-1.62). Patients with adj-ICI experienced significantly longer PFS than those without adj-ICI (HR 0.68, 95% CI 0.48-0.96) irrespective of definitive treatment (HR 0.65, 95% CI 0.37-1.13 in S group; HR 0.65, 95% CI 0.41-1.03 in RT group). However, OS did not significantly differ between those with and without adj-ICI (HR 0.96, 95% CI 0.59-1.56).

Conclusions

There were no significant differences in PFS and OS between the S and RT groups. Although the addition of adj-ICI yielded longer PFS in locally advanced HNMM patients, adj-ICI might not lead to a benefit in OS.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

National Cancer Center Research and Development Fund (2023-J-03) of Japan.

Disclosure

All authors have declared no conflicts of interest.