If you are a woman and have been assigned night shifts at workplace for long, be a little concerned about your health. According to new research, continous shifts at irregular hours may increase the risk of common cancers among women. The researchers found that overall, long-term night shift work among women increased the risk of cancer by 19 per cent. Of all the occupations analysed, nurses had the highest risk of developing breast cancer if they worked the night shift. "Our study indicates that night shift work serves as a risk factor for common cancers in women," said Xuelei Ma, co-author of the study from West China Medical Center of Sichuan University in Chengdu, China. For the study, published in the journal Cancer Epidemiology, Biomarkers & Prevention, researchers performed a meta-analysis using data from 61 articles comprising 114,628 cancer cases and 3,909,152 participants from North America, Europe, Australia and Asia. The articles consisted of 26 cohort studies, 24 case-control studies and 11 nested case-control studies. These studies were analysed for an association between long-term night shift work and risk of 11 types of cancer. When analysing specific cancers, the researchers found that this population had an increased risk of skin (41 per cent), breast (32 per cent), and gastrointestinal cancer (18 per cent) compared with women who did not perform long-term night shift work. A further analysis was conducted which looked specifically at long-term night shift work and risk of six types of cancer among female nurses. Among female nurses alone, those who worked the night shift had an increased risk of breast (58 per cent), gastrointestinal (35 percent) and lung cancer (28 percent) compared with those that did not work night shifts. "Nurses that worked the night shift were of a medical background and may have been more likely to undergo screening examinations," the researcher suggested. The 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," Ma noted.