Women who work night shifts more likely to get cancer, finds study

Risks increases by about 3.3 per cent 'for every five years spent doing regular night shift work'

Night shifts are becoming increasingly common and researchers warn employers must take steps to protect staff health (Getty)

Women who work night shifts are 20 per cent more likely to develop some form of cancer, with nurses being particularly at risk, according to new research.

Breaking down risk by length of time spent working nights, researchers in China predicted that risks increased by about 3.3 per cent “for every five years spent doing regular night shift work”.

They came to the conclusion after analysing 61 studies which examined a link between long-term night shifts and 11 different cancers.

Overall they found that women who worked nights were 20 per cent more likely to have a diagnosis at some point.

“Given the expanding prevalence of shift work worldwide and the heavy public burden of cancers, we initiated this study to draw public attention to this issue,” said lead author, Dr Xueliei Ma, an Oncologist at West China Medical Center of Sichuan University.

Researchers found that the night-shift workers were 41 per cent more likely to have skin cancers and 32 per cent more likely to have breast cancer.

However, the increased risk of breast cancer was only seen in European and North American populations.

The study, published in the journal Cancer Epidemiology, Biomarkers & Prevention, also analysed staff by occupation and found nurses who worked nightshifts had the highest increases in cancer risk of any occupational group.

They were 58 per cent more likely to develop the disease, compared to those who only worked days.

Previous studies have suggested that people who work night shifts are more likely to struggle to find time for exercise. They also have less healthy eating and lifestyle habits, like smoking, which are major risk factors for cancer and a range of other diseases.

But studies have also shown that the disruption night-shifts cause to sleep patterns has an impact that’s seen at a genetic level, and can through biological processes into “chaos”.

​There are around three million regular night shift workers in the UK, and Dr Ma says employers should take steps to offer their staff more regular health checks to mitigate these risks.

Nearly four million women from North America, Europe, Australia, and Asia took part in the studies evaluated by Dr Ma, and there were 114,000 individual cancer cases reported in this group.

Dr Ma speculated this could be because those working in medical roles are more aware of cancer screening programmes and so these are more likely to be picked up.

“Another possible explanation for the increased cancer risk in this population may relate to the job requirements of night shift nursing, such as more intensive shifts,” Dr Ma said. "Our study indicates that night shift work serves as a risk factor for common cancers in women."

She added: “These results might help establish and implement effective measures to protect female night shifters. Long-term night shift workers should have regular physical examinations and cancer screenings."