Adoption of Adjuvant Immunotherapy for Stage IIB/C Head and Neck Versus Nonhead and Neck Melanoma

INTRODUCTION: Immunotherapy for melanoma continues to increase, however its adoption has not been assessed across anatomic sites. This retrospective cohort study compared adoption rates of adjuvant immunotherapy in patients with stage IIB/C head and neck melanoma (HNM) compared to non-HNM after its approval by the United States Food & Drug Administration in 2021. METHODS: Patients with pathologic stage IIB/C primary cutaneous melanoma between 2018 and 2022 were identified in the National Cancer Database. Patients diagnosed in 2021 were excluded. A difference-in-differences analysis assessed the rate of adjuvant immunotherapy within 90 d of primary surgical resection among preapproval patients (2018-2020) versus postapproval patients (2022), stratified by anatomic site. RESULTS: Among 16,550 patients, 4917 (29.7%) had HNM and 11,633 (70.3%) had non-HNM. There was no difference in immunotherapy use between cohorts in the preapproval period (P = 0.590). Postapproval, adjuvant immunotherapy use increased significantly (+11% for HNM and +13% for non-HNM, p for both<0.001). Adjusted difference-in-differences analysis showed adjuvant immunotherapy adoption did not differ between HNM and non-HNM cohorts (P = 0.056). Adjuvant immunotherapy was negatively associated with older age (-0.2%, P < 0.001) and academic/research centers (-3.0%, P = 0.006). CONCLUSIONS: Despite historic differences in the management of HNM compared to non-HNM, adoption of adjuvant immunotherapy has been similar across patients' stage IIB/C melanoma regardless of anatomic site.