ESTRO 2024 - Abstract Book

S1461

Clinical - Head & neck

ESTRO 2024

be 94% in each arm, and compared against an unacceptable rate of 84%. Secondary endpoints included comparisons of OS and progression-free survival (PFS) between arms, and quality of life (QOL) metrics.

Results:

The trial was stopped early per protocol due to two treatment related deaths in the surgical arm. Sixty-one patients were randomized (n=30 in the RT arm and n=31 in the TOS + ND arm), with a median age of 62 years (interquartile range [IQR]: 57-68). The majority were male (n=51; 85%), and 51% (n=31) were never-smokers. The arms were well balanced. Median follow-up was 3.7 years (IQR: 3.1-4.5 years). In the RT arm, two-year OS was 100% (95% confidence interval [CI]: 100-100%), meeting the primary endpoint for acceptability (p=0.006). In the TOS + ND arm, two-year OS was 90% (95% CI: 71-97%), not meeting the primary endpoint (p=0.296), and significantly worse than in the RT arm (p=0.041; Figure 1A). Two-year PFS estimates were 100% (95% CI: 100-100%) vs. 86% (95% CI: 67-95%) respectively (p=0.012 comparing arms; Figure 1B). Mean (±SD) MDADI total scores at 2-years were 89 ± 13 vs. 83 ± 11, respectively (p=0.11), and grade 2-5 toxicity rates were similar (n=21 [70%] vs. n=24 [77%] respectively, p=0.51), with no additional grade 5 events.

Figure 1. Time-to-event outcomes: (a) overall survival, and (b) progression-free survival stratified by treatment arm. Abbreviations: RT - radiotherapy; TOS + ND - trans-oral surgery and neck dissection.

Conclusion:

For treatment de-escalation in patients with T1-2 disease amenable to transoral surgery, a primary RT approach achieved excellent oncologic and functional outcomes and should be tested in phase III de-escalation trials. (NCT03210103)

Keywords: oropharyngeal cancer, radiotherapy, surgery