CTLA4 and hereditary clear cell renal cell carcinoma: Second, although the total number of studies was not small, there were still not sufficient eligible studies for us to analyse different types of cancers, such as breast cancer, renal cell carcinoma or lung cancer, more studies are needed to research the potential relationship between the CTLA-4 60G/A (rs3087243) and CTLA-4 -1661A/G (rs4553808) polymorphisms and cancer susceptibility.