Furthermore, we detected the expression differences of 32 rhythm genes in cancer samples and normal samples from 14 cancer types, and the results showed that the expression of most of the detected rhythm genes are significantly changed (Figure 2B), among them, OPN4, MTNR1B, MTNR1A, AANTN, NPAS2, ARNTL2, and TIMELESS are significantly upregulated, whereas EGR3, RORB, PER3, PER1, and CRY2 are significantly downregulated in most cancer types (Figure 2C). This evidence concerns the gene PER1 and cancer.