ObjectiveTo systematically evaluate the efficacy of adjuvant radiotherapy after thymoma resection. MethodsThe PubMed, EMbase, The Cochrane Library, Web of Science, Wanfang, VIP, CNKI databases were systematically searched to find relevant literature comparing the efficacy and effectiveness of thymoma resection and thymoma resection+postoperative radiation therapy (PORT) for treating thymoma published from inception to January 2024. The Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of included retrospective studies, and Review Manager 5.4 software was used to perform meta-analysis. ResultsA total of 23 articles were included, all of which were retrospective studies. There were a total of 13742 patients, including 6980 patients in the simple surgery group, with 3321 males and 3659 females, and an average age of 54.08 years; 6762 patients in the surgery+PORT group, with 3385 males and 3377 females, and an average age of 53.76 years. The NOS scores of the included literature were all≥7 points. The results of the meta-analysis showed that compared with the simple surgery group, the surgery+PORT group had higher 1-year overall survival rate [OR=0.32, 95%CI (0.25, 0.42), P<0.001], 3-year overall survival rate [OR=0.55, 95%CI (0.48, 0.64), P<0.001], 5-year overall survival rate [OR=0.66, 95%CI (0.58, 0.75), P<0.001], 10-year overall survival rate [OR=0.71, 95%CI (0.57, 0.88), P=0.002], 1-year disease-free survival rate [OR=0.47, 95%CI (0.23, 0.93), P=0.030], 5-year disease-free survival rate [OR=0.61, 95%CI (0.45, 0.84), P=0.003], 3-year disease-specific survival rate [OR=0.44, 95%CI (0.35, 0.55), P<0.001], 5-year disease-specific survival rate [OR=0.53, 95%CI (0.44, 0.63), P<0.001] and 10-year disease-specific survival rate [OR=0.53, 95%CI (0.35, 0.82), P=0.004]. But there was no statistically significant difference between the two groups in terms of 3-year disease-free survival rate [OR=0.86, 95%CI (0.61, 1.22), P=0.400], 10-year disease-free survival rate [OR=0.70, 95%CI (0.47, 1.05), P=0.080] and 1-year disease-specific survival rate [OR=0.83, 95%CI (0.55, 1.26), P=0.380]. ConclusionPORT after thymoma resection has more advantages than simple surgical treatment in terms of 1-, 3-, 5-, and 10-year overall survival, 1- and 5-year disease-free survival, and 3-, 5- and 10-year disease-specific survival.