As reported in The Lancet by Thomson et al, the UK phase III TORPEdO trial has shown similar outcomes with intensity-modulated proton therapy (IMPT) vs intensity-modulated radiation therapy (IMRT) in patients with locally advanced oropharyngeal squamous cell carcinoma.
Study Details
In the multicenter open-label trial, 205 patients were randomly assigned 2:1 between February 2020 and June 2023 to receive IMPT (n = 136) or IMRT (n = 69); both groups received 70 Gy to the therapeutic target volume and 56 Gy to areas at lower risk of microscopic disease in 33 once-daily fractions over 6.5 weeks, together with two cycles of cisplatin at 100 mg/m² every 3 weeks. Co-primary endpoints at 12 months were gastrostomy tube dependence for nutrition or severe weight loss (≥ 20% from baseline) and University of Washington quality of life (UW-QoL) mean physical composite score (for saliva, taste, chewing, swallowing, speech, and appearance).
Key Findings
At 12 months, gastrostomy tube dependence occurred in 2 (2%) of 119 evaluable patients in the IMPT group vs 1 (2%) of 59 evaluable patients in the IMRT group, and severe weight loss occurred in 20 (18%) of 110 evaluable patients in the IMPT group vs 3 (6%) of 53 evaluable patients in the IMRT group (combined odds ratio = 2.80, 97.5% confidence interval [CI] = 0.75–10.4, P = .079). Mean UW-QoL physical composite scores at 12 months were 78.3 in the IMPT group vs 77.1 in the IMRT group (difference = 1.3, 97.5% CI = –3.7 to 6.2, P = .56).
At a median follow-up of 28.3 months (interquartile range = 26.5–39.3 months), 24-month freedom from locoregional recurrence rates were 94% (99% CI = 86%–98%) in the IMPT group vs 97% (99% CI = 82%–100%) in the IMRT group (hazard ratio [HR] = 2.6, 99% CI = 0.3–20.3, P = .24), and overall survival rates were 95% (99% CI = 86%–98%) in the IMPT group vs 95% (99% CI = 81%–99%) in the IMRT group (HR = 1.6, 99% CI = 0.3–8.8, P = .47).
No acute or late radiation–related grade 4 or 5 adverse events were reported. The most common acute grade 3 adverse events (during radiotherapy until 3 months postradiotherapy) in both the IMPT and IMRT groups were oral or pharyngeal mucositis or pain (37% and 54%), dysphagia (12% and 24%), and weight loss (11% and 10%). The most common late grade 3 adverse events (6–24 months postradiotherapy) in both groups were weight loss (14% and 14%) and hearing impairment (10% and 8%).
The investigators concluded: “IMPT and IMRT had similar late physical quality of life scores, gastrostomy-tube dependence, local control, and overall survival. In health-care settings where IMPT is not used routinely for oropharyngeal squamous cell carcinoma, IMRT remains the standard of care.”
David J. Thomson, MD, of The Christie NHS Foundation Trust, Manchester, UK, is the corresponding author for The Lancet article.
DISCLOSURE: The study was funded by Cancer Research UK. For full disclosures of the study authors, visit thelancet.com.
