Evaluation of the prognostic impact of postoperative adjuvant radiotherapy on head and neck mucosal melanoma: a meta-analysis

Background: Head and neck mucosal melanoma (HNMM) is a rare type of malignant tumor that frequently exhibits postoperative recurrence and distant metastasis. Many clinicians administer postoperative adjuvant radiotherapy to improve patient prognosis and enhance quality of life; however, the effects of this treatment remain controversial. Therefore, in this study, a meta-analysis was performed to evaluate the practical value of postoperative adjuvant radiotherapy for head and neck mucosal melanoma. Methods: Articles in the PubMed, MEDLINE, Cochrane Library, Web of Science and EMBASE databases were systematically retrieved. Analyses were conducted to compare the impact of treatments involving postoperative radiotherapy with treatments entailing surgery alone on patient overall survival time, local recurrence and distant metastasis. The hazard ratio (HR) was used to evaluate the time-to-event data employing RevMan version 5.2 and Stata/SE version 13.0 software according to the principles specified for systematic reviews of interventions in the Cochrane handbook. Results: Twelve cohort studies involving 1593 patients satisfied the desired conditions. In comparing surgery alone with postoperative radiotherapy, there was no significant difference regarding a decrease in the death risk in HNMM patients (HR, 1.07; 95 % CI, 0.95-1.2; p = 0.903; low heterogeneity, I-2 = 0); this was also the case for sinonasal melanoma after subgroup meta-analysis (HR, 1.04; 95 % CI, 0.8-1.36; p = 0.983; low heterogeneity, I-2 = 0 %). A sensitivity analysis and subgroup meta-analysis showed that disease progression was the main source of the instability in the results. Surgery combined with postoperative radiotherapy reduced the risk of local recurrence (HR, 0.51; 95 % CI, 0.35-0.76; p = 0.155) but did not reduce the risk of distant metastasis (HR, 2.26; 95 % CI, 1.01-5.05; p = 0.006). Conclusions: This study demonstrated that for HNMM patients surgery is recommended if indicated, and surgery combined with postoperative radiotherapy is also recommended for dramatically improved local control of the tumor bed. For patients not suitable for surgical treatment, radiotherapy is still advised. To control distant metastasis and finally lower the risk of death, immunological therapy is another potential option whose therapeutic effect needs to be proved with more data from clinical trials.