PER1 and breast cancer: CLOCK1, CRY1, CRY2, NPAS2, PER1, RORA and TIMELESS variants are associated with breast cancer risk [5,28–33], while polymorphisms in BMAL1, CLOCK1, CRY1, CRY2, CSNK1E, NPAS2, PER1, PER2, and PER3 are associated with prostate cancer risk [34–36].