The Health and Safety Executive (HSE) has commissioned research into the potential link between working night shifts and a greater incidence of *** cancer.

The move follows publication of a new Danish study which concluded that night shift work was associated with a 40 per cent increased risk in women.

The HSE told PM that while no causal link had been established, it had commissioned the University of Oxford to undertake an extensive study into the relationship between shift work and chronic diseases, particularly *** cancer.

The watchdog described the research as “complex and challenging” and estimated that the study would be completed by December 2015.

In England, women currently have a one in eight chance of developing *** cancer during their lifetime, with eight out of 10 cases diagnosed in women over 50 years old.

The World Health Organisation’s International Agency for Research on Cancer said five years ago that shift work which involved disruption to circadian rhythms – biological processes based on a 24-hour cycle – was “probably carcinogenic to humans”.

That prompted Denmark to introduce a compensation system for women suffering from *** cancer who had worked night shifts for longer than 20 years, paid for through employer insurance.

The latest research from the Danish Cancer Society was based on a case-control study of 15,500 women who worked in the military, according to a report in the Guardian.

It found that women who had worked nights at least three times a week for at least six years were more than twice as likely to have the disease as those who had not. But there was “a neutral link” for those who worked only one or two night shifts per week.

The study also investigated whether risk factors were associated with a lack of sun exposure and vitamin D, but discovered that night staff tended to sunbathe more than those who worked during the day.

Commenting on the Danish research, Lisa Wilde, director of research at *** Cancer Campaign, told the newspaper: “Night shift working and *** cancer risk is a hugely complex area and two of the biggest risk factors – diet and physical activity outside of working hours – weren't considered in this study. So, whilst it contributes to the debate, further research is needed to fully understand the link between night shift working, the lifestyle factors and *** cancer.”

Cancer Research UK added that there was strong evidence the risk of *** cancer could be reduced by maintaining a healthy weight, drinking less alcohol and being physically active.