Association between shift work, sleep disorder, and risks of cancers and chronic kidney disease
Night shift work has been classified as a probable carcinogen (cancer-causing substance) to humans in a recent expert review of the scientific literature convened by the International Agency for Research on Cancer (IARC) Monographs On the Identification of Carcinogenic Hazards to Humans (1). There are inconsistent findings from epidemiologic studies whether shift work plays a key role in increasing risk of various cancers such as cancers of breast, prostate, and colon/rectum (2-8). Animal studies also have shown that constant exposure to light increased incidences of liver cancer, lung cancer, and skin cancer (9, 10). IARC has not yet evaluated the evidence regarding the relationship between sleep disorders and cancer risk, however, it has been shown that sleep apnea and sleep-disordered breathing are important factors for cancer risk and cancer death (12-16). There is limited but increasing evidence that both shift work and sleep disorders reduce kidney function and increase risk of chronic kidney disease (17-21). Patients having sleep-related breathing problems usually do not have enough oxygen in their tissues and may develop chronic kidney disease (22). Thus, we propose to conduct epidemiologic studies to investigate whether shift work or sleep disorder is associated with an increased risk of selected cancers or chronic kidney disease.
Findings from our proposed study will provide new evidence regarding the relationships between shift work, sleep disorders and risks of several cancers, as well as chronic kidney disease, which will inform upcoming IARC meeting to evaluate whether they are important risk factors of developing cancers.