Long-term follow up of E3311, a phase II trial of transoral surgery (TOS) followed by pathology-based adjuvant treatment in HPV-associated (HPV+) oropharynx cancer (OPC): A trial of the ECOG-ACRIN Cancer Research Group.
Authors: Barbara Burtness, Yael Flamand, Harry Quon, Gregory S. Weinstein, Ranee Mehra, Joaquin J. Garcia, Seungwon Kim, Bert W. O'malley, Enver Ozer, Wayne Koch, Neil D. Gross, Richard Bryan Bell, Mihir R. Patel, Miriam Lango, Luc Morris, Russell Smith, Daniel Karakla, Jeremy Richmon, Floyd Christopher Holsinger, Robert L. Ferris
Journal: Journal of Clinical Oncology (2024)

6009 Background: E3311 is a phase II trial of TOS by credentialed surgeons with pathology-driven deintensified post-operative management in HPV+ OPC. Intermediate risk patients were randomized between standard and reduced dose radiation. We present mature outcome data, at median follow up of 52.4 months (m). Methods: Patients were eligible who had resectable cT1-2 stage III/IV AJCC7 p16+ OPC without matted neck nodes. Those with clear margins, 0-1 + nodes (LN), and no extranodal extension (ENE) were observed (Arm A, N=38); those with clear margins, 2-4 + LN, or ENE ≤1mm were randomized to 50Gy (Arm B, N=100) or 60Gy (Arm C, N=108); those with involved margins, &gt;4 + LN, or &gt;1mm ENE received weekly cisplatin 40 mg/m 2 and 60-66Gy (Arm D, N=113). Progression-free survival (PFS) and overall survival (OS) were estimated by the Kaplan-Meier method and compared using a log-rank test, stratified by arm for comparisons of primary site and smoking history. Results: Among 359 evaluable patients, 54-m PFS and OS were 90.6% (90% CI: 87.2%, 93.1%) and 95.3% (90% CI: 93.0%, 96.9%). 54-m PFS by arm was: A 93.2% (90% CI: 79.6%, 97.8%); B 94.9% (90% CI: 89.7%, 97.5%); C 90.2% (90% CI: 82.7%, 94.6%) and D 85.5% (90% CI: 77.5%, 90.8%). 54-m OS by arm was: A 97.1% (90% CI: 85.7%, 99.4%); B 97.9% (90% CI: 93.5%, 99.3%), C 95.1% (90% CI: 90.1%, 97.6%) and D 92.5% (90% CI: 86.9%, 95.7%). Among patients in Arm A, 11 had N0 and 27 N1 stage. Median Arm A lymph node yield (LNY) was 29 (11 to 91 LN) and did not differ for patients with/without recurrence (p=0.83). All Arm A recurrences were in N1 patients: 1 at 18 m and 3 at &gt; 40 m. No significant difference in PFS or OS was observed by prescribed radiation dose for intermediate risk patients (Arm B vs. C). Outcome did not differ by primary site of tonsil vs. other OPC (oOPC): 54-m PFS Tonsil 89.3% (90% CI: 84.9%, 92.5%) vs. oOPC 92.9% (90% CI: 87.0%, 96.2%), p=0.28, and 54-m OS Tonsil 94.6% (90% CI: 91.5%, 96.6%) vs oOPC 96.6% (90% CI: 92.4%, 98.5%), p=0.35. Smoking history also did not impact outcome. 54-m PFS was 89.9% (90% CI: 85.9%, 92.9%) for those with ≤10 pack-years (PY) tobacco exposure and 91.7% (90% CI: 83.9%, 95.9%) for those with &gt;10 PY. Conclusions: TOS, neck dissection with deintensified risk-based post-operative management results in outstanding 54-m PFS and OS across all subsites of T1-2 p16+ OPC, irrespective of smoking history. Late recurrence is not increased when post-operative radiation is reduced from 60 to 50Gy for intermediate risk patients. Pathologic &gt;1mm ENE (N=87), involved margin (N=12) or &gt;4 involved LN (N=30) accurately identify patients at increased recurrence risk and outcomes were favorable among such patients. Among patients with favorable pathologic characteristics, a subset with N1 disease are at risk for late recurrence and further characterization of these patients is warranted. Clinical trial information: NCT01898494 .