The genetic factors that give sufferers of endometriosis a higher risk of ovarian cancer have been explained, and the connection could increase the chances of finding treatments for both.
Endometriosis – where tissue similar to the lining of the womb grows outside the uterus – is among the most under-diagnosed diseases in countries where healthcare is sufficient to identify other common conditions. On average, it takes women suffering from it seven years to get diagnosed, because so many doctors dismiss descriptions of horrifying period pain, nausea, and other symptoms produced when the cells respond to hormones as if they were where they should be. Indeed, it's apparently easier to get funding to study whether having endometriosis makes women more attractive to men than for research to treat its effects.
This neglect may not only leave women to suffer intense pelvic pain and potential infertility, but it could also risk their lives following evidence those with endometriosis also carry a slightly heightened risk of epithelial ovarian cancer. However, a new paper in Cell Reports Medicine offers hope that the link could be turned to the advantage of sufferers of both conditions.
Although rarely directly fatal, the paper notes endometriosis “shares features with cancer, including metastatic-like behavior, tissue invasion, proliferation, angiogenesis [formation of blood vessels], and decreased apoptosis [normal cell death].”
The authors studied the genomes of 25,000 sufferers of ovarian cancer and 15,000 people with endometriosis. Such large sample sizes allowed them to look for features unusually common in both groups.
“Our research shows that individuals carrying certain genetic markers that predispose them to having endometriosis also have a higher risk of certain epithelial ovarian cancer subtypes, namely clear cell and endometrioid ovarian cancer,” lead author Dr Sally Mortlock of the University of Queensland said in a statement.
Rather than a single common gene, the authors found 28 locations within the human genome associated with both conditions, with a shared underlying signal at 19 of them. Identification of those genes offers a set of targets for researchers to work on, either through gene therapy or by identifying the proteins the genes code for.
For the one in nine women with endometriosis, knowing they are also at extra risk of ovarian cancer could add anxiety to everything else they are going through. However, Mortlock notes the extra danger only applies to certain forms of ovarian cancer – clear cell and endometrioid – and consequently the extra risk is small.
“Overall, studies have estimated that 1 in 76 women are at risk of developing ovarian cancer in their lifetime and having endometriosis increases this slightly to 1 in 55, so the overall risk is still very low,” Mortlock said. A very weak correlation was also found with high-grade serous ovarian cancer.
The findings, therefore, could be more important for the research implications than what they say about an individual's personal danger.
Nevertheless, if the message of the connection to cancer sinks in, this might be one way to get more doctors to take patients seriously when they describe endometriosis symptoms, which would be significant indeed.