Postoperative Intensity-Modulated radiotherapy with trigeminal nerve pathway delineation for head and neck adenoid cystic carcinoma.

Abstract

Head and neck adenoid cystic carcinoma (HN-ACC) is a rare, aggressive malignancy prone to perineural invasion, making treatment challenging. This study evaluates the outcomes of postoperative intensity-modulated radiation therapy (IMRT) for HN-ACC to guide radiation target delineation, optimizing radiation planning and improving patient outcomes. A retrospective review of postoperative IMRT outcomes in HN-ACC patients from January 2015 to December 2022 was conducted. Prophylactic coverage of trigeminal nerve branches in the radiation field and cervical nodal irradiation was based on clinical/pathological assessments. The primary endpoint was 5-year locoregional recurrence-free survival (LRRFS), with secondary endpoints including progression-free survival (PFS), distant metastasis-free survival (DMFS), and overall survival (OS). A total of 328 patients were followed for a median of 61.1 months. The 5-year LRRFS, PFS, DMFS, and OS rates were 91.7 %, 63.0 %, 67.1 %, and 91.3 %, respectively. Thirty patients experienced locoregional recurrence, comprising 19 local recurrences, 6 regional recurrences, and 5 combined local and regional recurrences. Eleven patients had recurrence involving trigeminal nerve branches (8 in-field, 3 marginal). Postoperative IMRT for HN-ACC, utilizing our institutional target delineation protocol that prioritizes delineating the target along the trigeminal nerve pathway, suggests favorable locoregional control and survival outcomes. These results suggest evidence-based insights that could inform clinical practice and support radiation oncologists in optimizing IMRT strategies for HN-ACC.