American College of Radiology ACR Appropriateness Criteria RETREATMENT OF RECURRENT HEAD AND NECK CANCER AFTER PRIOR DEFINITIVE RADIATION

Introduction/Background Despite treatment intensification for patients with head and neck squamous cell carcinoma (HNSCC), including altered radiation fractionation and the addition of chemotherapy to radiation, physicians and patients still face the challenge of recurrent or second tumors arising within or in close proximity to previously irradiated tissues. At 5 years after therapy, locoregional recurrences developed in 16%–25% of patients treated with definitive chemoradiation for larynx preservation [1] or with postoperative chemoradiation for high-risk HNSCC [2,3], and in 17%–52% of patients treated with definitive chemoradiation for locally advanced unresectable disease [4,5]. Locally recurrent tumors may arise from residual neoplastic cells that survive initial treatment, perhaps because of biological parameters and tumor molecular profiles [6] associated with radiosensitivity [7]. Insufficiencies in initial radiation treatment parameters, such as radiation dose, volume, fractionation, and treatment duration, were noted in a high percentage of patients enrolled on a small phase I trial of reirradiation [8] and are other potential sources of recurrence. Second cancers may arise from underlying field cancerization [9] as a radiation-induced malignancy or as a de novo process. A second HNSCC arising in the vicinity of the prior tumor may be indistinguishable from a local recurrence of the primary tumor [10]. Approximately 15% of patients have developed a second primary cancer within 5 years of radiation alone for HNSCC, and approximately one-quarter of these are in the head and neck [11].