Frequent working at night could place shift workers at increased cancer risk because of the suppression of the hormone melatonin, Canadian researchers have found.
Scientists from the University of Quebec looked at a population-based control study in Montreal between 1979 and 1985, which analysed job histories, including work hours, from 3137 men with incident cancer and 500 clear of the disease.
Compared with men who never worked at night, male night-shift workers were almost three times as likely to develop prostate cancer. The latter were also more than twice as likely to develop pancreatic cancer, rectal cancer and non-Hodgkin’s lymphoma.
It is believed that working night shifts could suppress melatonin, which helps regulate sleep patterns. More of the hormone is produced at night to help induce sleep, but working regular night shifts could disrupt this process and encourage tumour growth, according to researchers.
The study found no evidence that risk increased in line longer periods of night work.
Previous studies have identified a link between working night shifts and a rise in breast cancer among women.
The results of the Canadian study were published in the American Journal of Epidemiology.
