Curative-Intent Radiotherapy, IMPT Show More Benefits for Oropharyngeal Carcinoma

Analysis shows that the therapy is associated with a reduced acute toxicity burden associated with intensity-modulated radiation therapy.

Curative-intent radiotherapy with intensity-modulated proton therapy (IMPT) for nonmetastatic oropharyngeal carcinoma (OPC) was associated with a significantly reduced acute toxicity burden associated with intensity-modulated radiation therapy (IMRT), with just a few chronic toxic effects and favorable oncologic outcomes, according to the results of a study published in JAMA Network Open.

Investigators called for prospective randomized clinical trials comparing the 2 technologies and patient-reported outcomes.

In the study, 292 individuals with OPC were included, with 87% being men and the median age aged 64 years. Approximately 20% were treated with IMPT and the rest with IMRT. The median follow-up time was 26 months.

Individuals in the study were adults with newly diagnosed nonmetastatic OPC who received curative-intent radiotherapy with IMPT or IMRT at the Memorial Sloan Kettering Cancer Center between January 1, 2018, and December 31, 2021. The follow-up took place through December 31, 2021.

Most patients were treated with a dose of 70 Gy to the primary tumor. Additionally, approximately 98% of those on IMPT and 92% on IMRT had human papillomavirus (HPV)-p16-positive disease.

Investigators found no significant differences in the 3-year overall survival rate in the IMPT group and IMRT group at 97% and 91%, progressive-free survival at 82% and 85%, and locoregional recurrence at 5% and 4%, respectively.

However, they noted that the incidence of acute toxic effects was significantly higher for IMRT at 93% compared with IMPT at 72% for oral pain of grade 2 or greater, dysgeusia of grade 2 or greater at 57% and 28%, grade 3 dysphagia at 12% and 7%, mucositis of grade 3 or greater at 70% and 53%, nausea of grade 2 or greater at 8% and 0%, xerostomia of grade 2 or greater at 29% and 21%, and weight loss of grade 2 or greater at 59% and 37%, respectively.

There were also no differences reported in chronic toxic effects of grade 3 or greater. However, there was a significant difference for chronic xerostomia of grade 2 or higher at 11% for IMPT and 10% for IMRT.

Furthermore, 4 individuals who received IMRT had a percutaneous endoscopic gastrostomy tube for longer than 6 months.

The PEG tube placement was significantly reduced, because of treatment with IMPT during the acute phase and absent during the chronic phase, investigators said.

Investigators also noted limitations of the study, which were consistent with the retrospective nature, limiting the strength of conclusions based on potential associations.

Additionally, they said the results could have been limited to the small number of individuals in the IMPT group.

Likewise, another limitation could be an imbalance of median follow-up time in the IMPT and IMRT groups, because of more individuals being treated with IMPT in later years.

This could have affected the results around locoregional failure and chronic complications that could occur after 2 years, investigators said.

Reference

Youssef I, Yoon J, Mohamed N, Zakeri K, et al. Toxicity profiles and survival outcomes among patients with nonmetastatic oropharyngeal carcinoma treated with intensity-modulated proton therapy vs intensity-modulated radiation therapy. JAMA Netw Open. 2022;5(11):e2241538. doi:10.1001/jamanetworkopen.2022.41538