Prospective Registry Trial of Adjuvant High-Dose Rate Brachytherapy in Unirradiated Head and Neck Cancer: 20-Year Data

Background and Purpose: Full-dose postoperative external beam radiation therapy (EBRT)/chemoradiation is the standard of care in patients with resected, unirradiated head and neck cancer (HNC). This study aims to determine the long-term results of adjuvant high-dose rate (HDR) brachytherapy ± intermediate-dose postoperative external beam radiation therapy (EBRT)/chemoradiation in this HNC patient population. Materials and Methods: From 2000 to 2018, a total of 152 patients diagnosed with HNC were treated with surgery and adjuvant HDR brachytherapy alone (n = 32) or combined with EBRT ± chemotherapy (n = 120). Patients treated with brachytherapy alone received 32 or 40 Gy in 8 or 10 b.i.d. fractions. Combined modality patients received 16 or 24 Gy of HDR brachytherapy in 4–6 b.i.d. fractions followed by EBRT 45 Gy in 25 fractions ± chemotherapy. Results: Median follow-up was 8.1 years (range, 0.1–21.6). Forty patients (26.3%) developed RTOG grade ≥ 3 adverse events, mainly soft tissue necrosis (11.2%) and osteoradionecrosis (6.6%). The 5-year local and locoregional control rates were 85.5% and 74.9%, respectively. Five-year disease-free survival and overall survival rates were 54.9% and 62.2%, respectively. Conclusion: Adjuvant HDR brachytherapy alone or combined with EBRT is an adequate treatment option for HNC patients who are candidates to receive postoperative radiation/chemoradiation. The results obtained in terms of toxicity and locoregional control are comparable to standard chemoradiation. In addition, this study identifies a subset of patients that may benefit from adjuvant HDR in terms of reduced toxicity, provided that the high-risk CTV does not exceed 15 cm3 and is treated to EQD2-DVH TV100 doses of less than 87 Gy, together with a mandible2cm3 of less than 61 Gy.