Outcomes of postoperative radiotherapy combined with or without chemotherapy for locally advanced oral cancer: A systematic review and meta-analysis

Objective: Radiotherapy combined with chemotherapy or radiotherapy alone is an important treatment for locally advanced oral squamous cell carcinoma. We performed a meta-analysis of published reports about these two treatments. Methods: We performed an extensive exploration of various databases, such as Embase, PubMed, and the Cochrane Library. The study included research on the comparison between postoperative chemoradiotherapy (POCRT) and postoperative radiotherapy (PORT) for oral cancer, with a restriction on the search language to English. The included endpoints consisted of disease-free survival (DFS), overall survival (OS), locoregional control (LRC), and distant metastasis-free survival (DMFS). Results: Sixteen studies were included, including 3 prospective studies and 13 retrospective studies, with 3364 patients. For patients with locally advanced oral cancer, compared with PORT, POCRT had better DFS (HR 0.64; 95 % confidence interval [CI],0.48-0.84; P = 0.001), OS (HR 0.76;95 %CI 0.65-0.89; P = 0.0005), and LRC (HR 0.65;95 %CI 0.44-0.95; P = 0.02). There was a tendency for DMFS (RR 0.95;95 %CI 0.90-1.01; P = 0.09) to exhibit a marginal statistical distinction. The risks of grade 3 or higher acute toxicity, such as oral mucositis (RR 1.36; p = 0.44), dysphagia (RR 1.57; p = 0.13), and severe skin (RR 0.71; p = 0.17), were more frequent in the POCRT group, but the difference was not statistically significant. Conclusions: For patients with oral squamous cell carcinoma, POCRT is beneficial in terms of DFS, OS, and LRC, but there is no significant benefit in DMFS. The group receiving POCRT exhibited a slightly increased likelihood of experiencing oral mucositis and dysphagia, although the disparity did not attain statistical significance.