Studies on breast and prostate cancer on the interaction between night-shift work and circadian genes (Monsees et al., 2012; Grundy et al., 2013; Zienolddiny et al., 2013; Rabstein et al., 2014; Truong et al., 2014; Wendeu-Foyet et al., 2020) reported that polymorphisms in circadian genes ARNTL, CLOCK, CRY2, CSNK1E, NPAS2, PER2, PER3, RORA, and RORB were associated with the disease, particularly in night workers, i.e., individuals who are more subject to the disruption of circadian rhythms. The gene discussed is PER2; the disease is prostate cancer.