This review aims to systematically describe the biogenesis and degradation of circular RNAs (circRNAs), discusses the major functions of circRNAs, introduces the mechanisms by which circRNAs play a role in cancer, comprehensively summarize the relationship between circRNAs and anticarcinogen resistance as well as underlying specific mechanisms in multiple cancers. We screened and analyzed large quantity of scientific papers which associated with circRNAs, noncoding RNAs, function, cancer, drug resistance and chemoresistance, and then summarized in Figures 1 & 2 & Table 1. The biogenesis, degradation and function of circRNAs are specially compared with other noncoding RNAs, it can affect cancer pathogenesis and progression and are implicated in mediating resistance to various anticarcinogens in various types of cancer.