Working night shifts has been associated with obesity, heart disease and even some cancers. According to new evidence published in the journal Cancer Epidemiology, Biomarkers & Prevention, women who work these shifts over a long period of time are more likely to develop cancer, reports Medical News Today.

Investigators conducted a meta-analysis of 61 studies that included 3,909,152 participants and more than 114,000 cancer cases to examine the link between long-term night-shift work and the risk of developing 11 types of cancer. Participants were from Asia, Australia, Europe and North America. Moreover, researchers assessed the relationship between long-term night shifts among female nurses and six cancer types.

Women who worked long-term night shifts had a 19 percent increased risk for cancer. These women specifically had a 41 percent higher risk for skin cancer, a 32 increased risk for breast cancer and an 18 percent greater risk for gastrointestinal cancer. In addition, there was a 3.3 percent rise in breast cancer risk for each additional five years of night-shift work.

Findings from the study on female nurses found that there were greater risks for breast cancer (58 percent), gastrointestinal cancer (35 percent) and lung cancer (28 percent).

“Our study indicates that night serves as a risk factor for common cancers in women,” said Xuelei Ma, PhD, of the West China Medical Center at Sichuan University in China and the study’s coauthor. “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.”

Hopefully, Ma says, these findings will prompt larger group studies to further observe the association between long-term night-shift work and cancer in women.

Click here to learn how losing weight can lower a woman’s breast cancer risk.