Intra-treatment hypoxia directed major radiation de-escalation as definitive treatment for human papillomavirus-related oropharyngeal cancer.
NANCY Y. LEE, Eric J. Sherman, Heiko Schöder, Rick Wray, Charlie White, Lara Dunn, Tony Hung, David G. Pfister, Alan L. Ho, Sean M. McBride, Yao Yu, Kaveh Zakeri, Noah S. Kalman, Charles E. Rutter, Luc Morris, Bhuvanesh Singh, Jay Boyle, Ian Ganly, Richard J. Wong, Nadeem Riaz
Abstract
6007 Background: We previously reported that surgery to the primary site with hypoxia-directed de-escalated radiation to the neck for human papillomavirus associated oropharyngeal carcinoma (HPV+ OPC) can lead to excellent oncologic outcomes. We now report the results of a successor multi-center phase II trial of hypoxia-directed de-escalated chemoradiotherapy without surgery for HPV+OPC. Methods: HPV+ OPC (T0-2/N1-N2c/AJCC 7 th ) patients were eligible for enrollment. Tumors without evidence of hypoxia on 18 F-FMISO (fluoromisonidazole) PET received de-escalated chemoradiation to 30Gy while those with hypoxia received chemoradiation to 70Gy. The primary objective was achieving a 2-year locoregional control (LRC) of 95% (failure was locoregional recurrence where surgical salvage was unfeasible) with a 7% non-inferiority margin. We enrolled a total of 158 subjects upfront to account for a 5% loss due to death (of reasons other than cancer) or follow-up. Secondary objectives were local failure (LF), regional failure (RF), distant metastasis (DM), overall survival (OS), toxicities, and patient-reported MD Anderson Dysphagia Inventory (MDADI) scores. LF, RF, and DM were estimated using the Cumulative Incidence Function, and OS was estimated using the Kaplan-Meier method. Results were reported up to 1/31/2024. Results: From 4/28/20-4/17/23, 158 HPV+ OPC patients were enrolled where150 patients were eligible for analyses. Patient characteristics: Tonsil (43%); Base of Tongue (47%); unknown primary (10%); >/=10 pack years (22%); T0 (9%), T1 (44%), T2 (47%); N1 (14%), N2a (11%), N2b (59%), N2c (16%). 111 (74%) received 30Gy; 95% cisplatin. With 24 months (8-43) of median follow-up, the 2-year LF, RF, DM rates were 4.2%, 6.9%, 2.0%, respectively. The 2-year overall survival probability was 99%. Only 2 patients could not undergo salvage surgery [one 30Gy (second recurrence); one 70Gy (M1)], both received systemic therapy with durable response. Acute grade 3-4 toxicities were 32% (67% neutropenia). Mean MDADI scores: 92.93 (baseline); 68.24 (3 weeks), 91.45 (4 months) after chemoradiation. Conclusions: These early data indicate that major de-escalation to 30Gy based on hypoxia status achieved significant toxicity reduction without compromise in survival for HPV+ OPC treated with chemoradiation without surgery. Clinical trial information: NCT03323463 .