'Night shift link' to ovarian cancer
18 March, 2013
Los Angles: US researchers have found a link between working night shifts and the risk of ovarian cancer. A study of more than 3,000 women suggested that working overnight increased the risk of early-stage cancer by 49% compared with doing normal office hours.
One possible explanation was disruption of the sleep hormone melatonin, the researchers said. But experts warned more work was needed and there might be other explanations.
It does however follow an earlier association made between shift work and breast cancer. The International Agency for Cancer Research has previously identified working shift patterns that disrupt the body's natural "clock" as a probable cause of cancer.
In the latest investigation, researchers looked at 1,101 women with advanced ovarian cancer, 389 with borderline or early disease and 1,832 women without the condition.
Overall, a quarter with advanced cancer said they had worked night shifts, compared with a third of those with borderline disease and one in five of the control group.
Analysis of the data showed a 24% increased risk of advanced cancer and 49% increased risk of early-stage disease for night workers compared with those who worked during the day.
But the results were only significant for women over the age of 50, the researchers reported in Occupational and Environmental Medicine.
And the risk did not seem to increase for those who had worked night shifts for the longest.