Shift work can cause cancer. In the new issue of the Deutsches Ärzteblatt International (Dtsch Arztebl Int 2010; 107: 657-62), Thomas C. Erren and colleagues describe the current state of knowledge in this area and point out the challenges lying ahead.
Although it is well known that short-term disturbances of circadian rhythms, such as jet lag, can impair a person's sense of well-being, researchers only recently began to ask whether chronic disruption of biological rhythms over the long term might promote cancer. The possibility of financial compensation in such cases is already an immediately relevant political issue: in 2008, 38 women in Denmark who had worked the night shift and then developed breast cancer obtained official recognition of their disease as an occupational illness and were awarded compensation for it. The findings of the laboratory experiments performed to date in animals and cell preparations lend plausibility to the postulated link between shift work and cancer, yet there is still no answer to the central question whether these findings are applicable to humans. Even though the connection between shift work and cancer has not yet been definitively established, the authors make a case for recasting old-fashioned shift-work schedules in the light of recently gained insights from occupational medicine and chronobiology.