Survival without Quality of Life Deterioration in the GORTEC 2014-04 "OMET" Randomised Phase 2 Trial in Head and Neck Cancer Patients with Oligometastases using Stereotactic Ablative Radiotherapy (SABR)-alone or chemotherapy SABR.

Purpose: Patients with oligometastasis may have prolonged survival with multisite stereotactic ablative radiotherapy (SABR). Evidence to support this paradigm is scarce in squamous cell carcinomas of the head and neck cancers (HNSCC). The multicentre open-label randomised, GORTEC 2014-04 (NCT03070366) phase II study assesses survival without definitive quality of life (QoL) deterioration of omitting upfront chemotherapy in oligometastatic HNSCC patients by using SABR-alone.

Methods And Materials: Eligible participants (≥18 years-old with 1-3 oligometastases, ECOG score 0-2), were randomly assigned (1:1) to receive chemo-SABR or SABR-alone. Salvage treatments were left to physician's appreciation. The standard therapy was considered to be systemic therapy and SABR (chemo-SABR; EXTREME regimen). The primary endpoint was one-year (± 3 months) OS rate without definitive deterioration (i.e. without subsequent better QoL score) of the global QLCQ-C30 QoL score.

Results: Between Sept, 2015 & Oct, 2022, 69 participants were assigned to receive chemo-SABR (N=35) or SABR-alone (N=34); 57 had lung-only metastases (82.6%), 40 had isolated metastasis (58.0%). Median baseline QoL score was 66.7 (IQR[50.0-83.3]). Median follow-up was 55.3months (95%CI:45.0-69.7). Of participants (N=59) evaluable for the primary endpoint, 16/29 (55.2%, 90%CI:0.38-0.71), and 16/30 (53.3%, 90%CI:0.37-0.69) were alive and free of QoL deterioration at one year in the SABR-alone and chemo-SABR arms. However, QoL deterioration was deeper with chemo-SABR (50.0;IQR[41.7-66.7] than SABR-alone (16.7;IQR[16.7-41.7]). In intent-to-treat analysis (N=69), median survival was 42.3 months (95%CI:26.5-not reached) with chemo-SABR and 41.1months (95%CI:32.1-66.9) with SABR-alone; median PFS were 12.9 (95%CI:7.5-17.3) and 7.4months (95%CI:4.2-15.6) in the chemo-SABR and SABR-alone arms, respectively. Rates of severe treatment-related toxicities were 21/35 (60.0%) with chemo-SABR and 3/34 (8.8%, no grade 5) with SABR-alone.

Conclusion: Using SABR-alone, omission of upfront EXTREME-based chemotherapy and maintenance cetuximab in oligometastatic HNSCC patients resulted in similar survival but much less severe QoL deterioration and fewer toxicity rates. SABR alone could be a reasonable alternative in oligometastatic HNSCC patients.