CLOCK and cancer: Epidemiological studies have linked shift work and circadian disruption to a number of diseases that involve epithelial stem cells, including skin diseases and cancer.28 Systematic analysis across 32 human cancers revealed widespread clock gene alterations and disrupted circadian rhythms that correlated with oncogenic pathways and survival.29 Consistent with these findings, studies in mice have shown that jet lag paradigms or genetic circadian disruption accelerate lung30 and intestinal31,32 tumorigenesis.