Shift work and the risk of cancer–a systematic review

In 2007, the International Agency for Research on Cancer (IARC) classified shift work involving circadian disruption as “probably carcinogenic to humans”. A few epidemiological studies have sought to assess the association between shift work and the risk of cancer, although the results have been inconsistent. Thus, we aimed to conduct a systematic review of prospective cohort studies to summarize the epidemiological evidence of an association between shift work and the risk of cancer. The database used in this review was Medline/PubMed and search terms “shiftwork”, “shift work”, and “night work”. The limitations included text availability (free full text), language (English), search fields (title), and publication between January 2008 and January 2018. The search strategy resulted in twelve articles that met the selection criteria. Three studies presented results related to prostate cancer, two studies were related to lung cancer, four studies to breast cancer, and three studies related to other cancers. In conclusion, there is limited evidence of a causal association between night shift work and breast cancer, while there is insufficient evidence in respect to lung cancer, prostate cancer, and other cancers.