Proton Therapy Cuts Feeding Tube Dependence in Throat Cancer

Results from the phase 3 TORPEdO trial (ISRCTN 16424014) suggest that intensity-modulated proton therapy (IMPT) may offer a functional advantage over intensity-modulated radiation therapy (IMRT) for patients with locally advanced oropharyngeal squamous cell carcinoma, specifically in reducing gastrostomy-tube dependence and severe weight loss at 12 months.¹

Background and Rationale

IMRT with concurrent chemotherapy is the current standard of care for locally advanced oropharyngeal squamous cell carcinoma.^2,3 IMPT has emerged as a promising alternative because it can reduce radiation doses to organs at risk, including the contralateral parotid gland, oral cavity, and swallowing structures, potentially translating into fewer adverse physical effects compared with IMRT.

Trial Design

In this phase 3 randomized controlled trial, patients were assigned in a 2:1 fashion to receive either IMPT (n = 136) or IMRT (n = 69), each delivering 70 Gy with an elective dose of 56 Gy in 33 once-daily fractions over 6.5 weeks. The primary end point was reduction in treatment-related toxicities, with secondary end points focused on biomarker validation.

Key exclusion criteria included feeding tube insertion required before treatment, N3 disease, upfront neck dissection, induction chemotherapy use, contraindication to cisplatin for cycle 1 concurrent chemotherapy, and prior head and neck radiotherapy.

The study population was predominantly male (80%) and White (98%), with a median age of 57.1 years (range, 52.7-62.3). The most common primary disease sites were the tonsil (57%) and base of tongue (42%), with smaller proportions involving the posterior pharyngeal wall and soft palate (1% each). Regarding smoking history, 46% of patients were never smokers, 39% had quit more than 1 year prior, and 4% were current smokers.

Key Findings

The primary outcome of gastrostomy-tube dependence or grade 3 weight loss (at least 20% from baseline) at 12 months was evaluable in 178 patients (87% of 205 enrolled). IMPT significantly reduced this composite end point compared with IMRT (OR, 0.23;95% CI, 0.07–0.73; P =.01).

A closer look at the data reveals an important nuance, however. Event rates, driven primarily by weight loss, were higher in the IMPT group (18%; 97.5% CI, 11–27) than in the IMRT group (7%; 97.5% CI, 2.0-18.0), with an adjusted OR of 2.80 (95% CI, 0.75–10.41; P =.079).

Gastrostomy-tube dependence itself was low in both groups: 2% in the IMPT group and 2% in the IMRT group, a reduction from earlier time points in both arms.

The investigators note that the lower rate of feeding-tube placement with IMPT at the end of treatment, combined with a possible reluctance among patients and clinicians to insert tubes after treatment completion, likely contributed to the greater subsequent weight loss observed in the IMPT group.

Quality of Life and Swallow Function

Mean University of Washington Quality of Life (UW-QoL) scores for swallowing, chewing, taste, and saliva were similar between the groups from week 6 following chemoradiotherapy onward. However, a meaningful subset of patients in both arms reported persistent moderate-to-severe symptoms throughout the follow-up period.

Overall, IMPT and IMRT demonstrated comparable outcomes across late effects, physical quality of life, gastrostomy dependence, swallow function, local control, and overall survival. The TORPEdO trial provides robust, contemporary data on side-effect profiles and their trajectories with modern treatment approaches. The investigators concluded that “both modalities are effective and in settings where IMPT is not used routinely for oropharyngeal squamous cell carcinoma, IMRT remains the standard of care.”

REFERENCES

1. Thomson DJ, Price JM, Tyler M, et al. Proton beam therapy for oropharyngeal cancer (TORPEdO): a phase 3, randomised controlled trial. Lancet. 2026;407(10535):1259-1275. doi:10.1016/S0140-6736(26)00314-4

2. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology. Head and neck cancers. Version 1.2026-December 8, 2025. Accessed April 2, 2026. https://tinyurl.com/4pnr4t72

3. Mehanna H, Evans M, Beasley M, et al. Oropharyngeal cancer: United Kingdom National Multidisciplinary Guidelines. J Laryngol Otol. 2016;130(S2):S90-S96. doi:10.1017/S0022215116000505