Investigation of the feasibility of elective irradiation to neck level Ib using intensitymodulated radiotherapy for patients with nasopharyngeal carcinoma: A retrospective analysis

To assess the feasibility of elective neck irradiation to level Ib in nasopharyngeal carcinoma (NPC) using intensity-modulated radiation therapy (IMRT). Methods: We retrospectively analyzed 1438 patients with newly-diagnosed, non-metastatic and biopsy-proven NPC treated with IMRT.