Nurses in North America and Europe who work night shift long-term have a higher risk of developing breast cancer, according to a study to come out of China.

The study’s findings showed female nurses who worked the night shift had an increased rate of breast cancer by 58%, gastrointestinal cancer by 35% and lung cancer by 28% compared to those who did not work night shift.

The study used meta-analysis data from 61 articles, comprising 114,628 cancer cases and 3,909,152 participants from North America, Europe and Australia.

The study analysed for an association between long-term night shift and 11 types of cancers. A further analysis was conducted which specifically looked at night shift work and six types of cancers amongst female nurses.

Of all those the occupations analysed nurses had the highest risk of developing breast cancer if they worked night shift.

“Nurses that work night shift were of a medical background and may have been more likely to undergo screening examination,” said study lead Xuelei Ma from State Key Laboratory of Biotherapy and Cancer Center, West China Medical Center of Sichuan University, Chengdu, China.

“Another possible explanation for the increased cancer risk is that the population may relate to the job requirements of night shift nursing, such as more intensive shifts.”

Ma said that overall the association between night shift and breast cancer risk was found only among female night shift workers in North America and Europe.

According to Ma, the results of this research suggest the need for health protection programs for long-term female night shift workers. “Our study indicates that night shift workers serves as a risk factor for common cancers in women.

“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.” The study was published in Cancer Epidemiology, Biomarkers & Prevention.