Data Extraction and Study Quality

According to the PRISMA 2020 standard evaluation process ( Supplementary Material S1 ), each document was screened by two people independently reading the title and abstract, after which another two reviewers read the full text. When two reviewers disagreed, a third person judged. The literature screening process was strictly controlled to ensure the quality of the research. The main information extracted in this study was: the first author of the study, publication date, sample size, gender and age of the research subject, study time of the intended population, country, tumor type, radiotherapy technology and dose, treatment method during radiotherapy, CD3+ T lymphocyte, CD4+ T lymphocyte, and CD8+ T lymphocyte count or percentage. The quality of included articles was evaluated by a modification of the Newcastle-Ottawa Scale (NOS) provided by the Cochrane Collaboration.