Danish research suggests post-menopausal PCOS patients are at greater risk of developing the cancer, and developing it earlier.
The chance of an ovarian cancer diagnosis, though small, is doubled after menopause for those who have PCOS, according to new research from Denmark.
Ovarian cancer is rare, but it has a five-year survival rate of only 30-50% because it is not screened for and it’s usually detected only at an advanced stage.
“Therefore, identification of risk factors may play a crucial role in preventing epithelial ovarian tumours,” the authors wrote. Furthermore, incidence of PCOS was expected to increase due to growing rates of obesity, they said.
The findings, presented at a meeting of the European Society of Human Reproduction and Embryology in Copenhagen last week, showed that prior to menopause, women with PCOS had a similar risk for ovarian cancer to those without PCOS at any age (an age-adjusted incidence rate of 11.7 per 100,000 person-years, compared with 13.2 per 100,000 person-years for those without PCOS). Overall, there were no significant associations between PCOS and epithelial ovarian cancer or epithelial borderline ovarian tumours.
But after menopause, the groups diverged.
Researchers looked at records for all 1.7 million women born in Denmark from 1940 to 1993, 15,000 of whom had PCOS, for a median of 26 years until they reached a median age of 50. In that time, 6490 women were diagnosed with ovarian cancer and 2990 with borderline ovarian tumours.
The results showed more than a doubling in the risk of ovarian cancer diagnosis in postmenopausal women with PCOS compared to those without the condition (HR 2.28 95% CI 1.02-5.09).
Additionally, the study found more than twice the risk of serous borderline ovarian tumours, abnormal cells associated with cancer down the track, in women with PCOS of any age (pre- or post-menopause) compared with women without PCOS (HR 2.34 95% CI 1.21-4.53).
“Importantly, low statistical precision is a crucial limitation of our study and in previous studies and larger studies with longer follow-up are therefore warranted,” the authors noted.
Researchers took into account the potential confounders of education level, obesity and diabetes mellitus type II diagnoses, use of oral contraceptives, infertility treatment and birthing status.
The study’s findings that the risk differed only after menopause is different to other published findings which found an increased risk in pre-menopausal women and, in the authors’ words, “is not easily explainable”. They hypothesised that it could be due to a lesser risk in the early years of menopause, which then grows again with age and can only be detected in a very long study.
Moreover, the authors pointed out that it is not known exactly whether some elements of PCOS drive development of ovarian cancer – such as long-term exposure to hyperandrogenism, metabolic disorders and giving birth – and others – like oral contraceptive use and anovulation – protect against it.
“Thus, our results regarding the risk of ovarian cancer in women of all ages with a history of PCOS remain somewhat inconclusive and difficult to reconciliate with previous studies,” they wrote.
But they said the findings should be considered when formulating guidelines for the long-term healthcare of people with PCOS, which currently don’t include anything about the risk of ovarian cancer.
