Multicenter phase 3 trial of late functional, patient-reported, disease control and survival outcomes with IMPT versus IMRT for oropharyngeal cancer

In the phase 3 TORPEdO trial, at 20 UK centers, patients with locally advanced oropharyngeal squamous cell carcinoma (LA OPSCC) were randomized 2:1 to intensity-modulated proton therapy (IMPT; n=136) or intensity-modulated radiation therapy (IMRT; n=69) 70 Gy in 33 fractions for 6.5 weeks, in combination with two cycles of high-dose cisplatin every 3 weeks. Coprimary endpoints at 12 months were gastrostomy-tube dependence or severe weight loss (≥ 20% from baseline). Gastrostomy-tube dependence at 12 months occurred in 2% of patients in each group and severe weight loss in 18% in the IMPT group and 6% in the IMRT group (combined odds ratio 2.80; p=0.079). There were no significant differences for UW-QoL mean physical composite score for saliva, taste, chewing, swallowing, speech, and appearance. There were no treatment-related deaths. At median follow-up of 28.3 months (IQR 26.5-39.3), 24-month freedom from locoregional recurrence rates were 94% in the IMPT group versus 97% in the IMRT group (HR 2.6; p=0.24) and overall survival rates were 95% versus 95% (HR 1.6; p=0.47). The authors conclude that IMPT and IMRT for LA OPSCC had similar late physical quality of life scores, gastrostomy-tube dependence, local control, and overall survival.