How to accurately identify factors of cancer occurrence and to provide intervention early are the key issues that urgently needs to be addressed in cancer prevention and treatment. Mendelian randomization (MR) analysis uses genetic variants as instrument variables for exposures of interest, which compensates the shortcomings of traditional observational studies and clinical trials. This review introduced the current application status of MR analysis on cancer etiology and treatment researches in details, including assessment of cancer risk factors, exploration of cancer treatment targets, and evaluation of drug efficiency and adverse reactions. The scopes and dimensions of cancer etiology and treatment researches are greatly expanded because of various MR designs and abundant high-level omics data. As well, it provides a practical and feasible method for constructing cancer etiology networks and drug targeted databases, which are promising for supporting the development of precision cancer prevention and treatment.
Incidence rate is a common effect measure. The incidence rate ratio refers to the ratio of two different incidence rates. It is used to compare the difference in the number of cases per unit person-time between two groups. RevMan software can not perform a meta-analysis with the incidence rate ratio as the effect size at present. A set of simulation data was used to demonstrate a meta-analysis process with the incidence rate ratio as the effect size by using the meta package of R Studio software in this article.