Women with polycystic ovary syndrome (PCOS) who have been through menopause are more than twice as likely to be diagnosed with ovarian cancer, according to a study.

Presenting the study at the ongoing annual meeting of the European Society of Human Reproduction and Embryology (ESHRE) in Copenhagen on June 26, the researchers called for increased awareness when managing the health of patients with PCOS, which affects an estimated one in ten women globally.

The research, also published in the International Journal of Cancer, did not examine why postmenopausal women were more likely to develop ovarian cancer.

However, lead author Dr Clarissa Frandsen from the Danish Cancer Society said PCOS is a complex condition and long-term exposure to potential cancer-causing factors could be behind the finding, such as excess production of male sex hormones.

Ovarian cancer is not as prevalent as breast cancer but is three times more deadly. The analysis by the Danish Cancer Research Center and Herlev Hospital in Denmark focused on epithelial ovarian cancer. The disease starts on the surface of the ovary and accounts for the majority (90 per cent) of ovarian tumours.

The study included all 1.7 million women born in Denmark between January 1, 1940, and December 31, 1993, and followed them for 26 years. The results showed that 6,490 women were diagnosed with epithelial ovarian cancer and 2,990 with borderline ovarian tumours.

While the increased risk was not statistically significant for ovarian cancer and borderline ovarian tumours among women with PCOS, the risk of developing ovarian cancer was significantly greater among postmenopausal women compared to those without PCOS.

In addition, the risk in general was more than double for a type of ovarian tumour known as serous borderline among PCOS patients. These abnormal cells are not classed as cancer but are not completely benign and studies show they can lead to ovarian cancer later on.

“Our results and those from previous studies should be taken into account when revising guidelines on how to manage the health of women with PCOS in the long term,” said Dr Frandsen.

“Unfortunately, there is no effective screening for early detection of ovarian cancer. Both patients and clinicians will benefit from improved knowledge of the potential long-term health risks associated with PCOS,” she added.