There are strong genetic links between endometriosis and ovarian cancer subtypes, according to new Australian research, increasing scientists' understanding of the diseases.
The release of the new findings coincides with Endometriosis Awareness Month, an annual event observed worldwide to fundraise and build education around the chronic disease.
Endometriosis is an often painful disorder in which tissue similar to the tissue that normally lines the inside of the uterus, the endometrium, grows outside of the uterus. The tissue can be found on the ovaries, fallopian tubes, the tissue lining the pelvis or the intestines, causing pain, menstrual irregularities and sometimes infertility.
It can be a debilitating disease, affecting the health of one in nine women of reproductive age.
As part of the study, researchers from the University of Queensland, Queensland University of Technology, the University of Melbourne and the QIMR Berghofer Medical Research Institute combined meta-analyses - a statistical analysis that combines the results of multiple scientific studies - looking at the genetic factors influencing both endometriosis and ovarian cancers.
Dr Sally Mortlock and Professor Grant Montgomery from the University of Queensland's Institute for Molecular Bioscience carried out a large study to identify a genetic basis for this risk, with the aim of better understanding the biological overlap between the reproductive disorders.
The team used a technique called 'Mendelian Randomisation', in which the use of genetics allows scientists to determine whether one thing causes another, rather than just identifying a link.
The researchers say their findings show a causal link between endometriosis and a risk of multiple types of ovarian cancer, which could support additional ovarian cancer screening for women with endometriosis in the future.
Previous studies have also demonstrated that endometriosis sufferers have a slightly increased risk of developing epithelial ovarian cancer, the most common type of ovarian cancer. This cancer develops in the epithelial tissue, a thin lining that covers the outside of an ovary. Cancer may also form in the lining of a fallopian tube, or it can begin in the peritoneum, the tissue that covers your abdominal organs, according to the Cleveland Clinic.
"More information about how [the diseases] develop, their associated risk factors, and the pathways shared between endometriosis and different types of ovarian cancer has been needed," Dr Mortlock said.
"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."
Although the diseases are genetically linked, the risk of ovarian cancer for those with endometriosis is not substantially increased, Dr Mortlock added.
"Overall, studies have estimated that one in 76 women are at risk of developing ovarian cancer in their lifetime and having endometriosis increases this slightly to one in 55, so the overall risk is still very low," she said.
The study found genes that could be drug targets to treat both endometriosis and epithelial ovarian cancer in the future.
"We explored specific areas of DNA that increase the risk of both diseases and identified genes in ovary and uterus tissue that could be targets for therapy," Dr Mortlock said.
"[They] may be valuable to understand the link between the disorders and to disrupt biological pathways initiating cancer."
The researchers combined large datasets comparing the genomes of 15,000 people with endometriosis and 25,000 with ovarian cancer to find an overlap in risk factors between the two diseases.
The collaboration also involved Associate Professor Kate Lawrenson at Cedars-Sinai Medical Center in Los Angeles, US and Dr Siddhartha P Kar from England's University of Bristol.
The study was published in the journal Cell Reports Medicine this week.
