Toxicity and Oncologic Outcomes of Proton Radiotherapy for Oropharyngeal Cancer: A Systematic Review and Meta-Analysis
Faculty and Abstracts
Purpose: Intensity modulated radiotherapy (IMRT) for oropharyngeal cancer is associated with acute and late toxicities that impact patient quality of life. Proton RT (PRT) can reduce exposure to surrounding tissues, but the clinical magnitude of this advantage is unclear. The objective of this study is to determine the rates of acute and late toxicities and oncologic outcomes associated with PRT for patients with oropharyngeal cancer.
Methodology: Databases (Pubmed, Embase, Web of Science, Cochrane Library) were queried for peer-reviewed, English language, articles published between 01/01/80 and 11/12/22. Included studies reported toxicity or oncologic outcomes from at least 10 patients treated with PRT for the upfront management of oropharyngeal cancer. Excluded studies lacked full text, reported results from databases/systematic reviews, or included patients treated with re-irradiation. Data were extracted following PRISMA guidelines. Pooled outcomes were estimated using random-effects models. Comparisons between PRT and IMRT were performed using log-odds ratios. Primary outcomes were the pooled rates of adverse events (acute or late), overall survival (OS), and progression free survival (PFS) following with PRT.
Results: A total of 16 studies (14 retrospective, 2 prospective) consisting of 843 patients treated with PRT were identified. Among these studies, pooled rates of acute grade 3+ dermatitis, mucositis, xerostomia, dysphagia, and weight loss were 22%, 38%, 1.6%, 15%, and 1.9%, respectively. Pooled rate of acute hospitalizations was 10%. Among studies reporting late toxicities, the rates of grade 3+ xerostomia and dysphagia were 1.2% and 2.6%, respectively. Compared to IMRT, PRT was associated with lower rates of acute feeding tube use (18% versus 28%, P< 0.001), but not long term feeding tube use (1.4% versus 2.7%, P=0.24). After PRT, OS at 2- and 3-years was 98% and 96%, while PFS at 2- and 3-years was 93% and 86%.
Conclusions: PRT for patients with oropharyngeal cancer is associated with favorable toxicity and oncologic outcomes and may have an improved acute toxicity profile when compared to IMRT. While randomized clinical trials are ongoing, these data provide the highest level of evidence to support PRT in the upfront treatment of oropharyngeal cancer.
