[Cancer risk among shift workers: a review].

INTRODUCTION: According to IARC, shift work resulting in disruption of circadian rhythm is a probable human carcinogen (Group 2A). METHODS: We examined the scientific literature on the carcinogenic risk among shift workers for risk assessment purposes. RESULTS: Clock genes polymorphisms might contribute with suppression of melatonin synthesis, immuno-suppression from sleep deprivation, individual habits associated with shift work, and low vitamin D levels, in increasing risk of breast cancer, prostate cancer and lymphoma among shift workers. CONCLUSION: Although the epidemiological evidence seems scanty, the hypothesis that shift work-related sleep deprivation would contribute to increasing cancer risk seems based on solid ground.