Endometriosis linked to 3 types of ovarian cancer
Published Tuesday, February 21, 2012 7:19PM EST
Women who suffer from endometriosis may have a higher risk of developing three types of ovarian cancer, a new study says.
Endometriosis is a gynaecological disorder that affects an estimated 10 per cent of women of reproductive age.
The research, published in the online edition of The Lancet Oncology, calculated the association between endometriosis and the risk of the five major types of ovarian cancer: high-grade serous, low-grade serous, clear cell, endometrioid and mucinous carcinomas.
The researchers looked at data from 13 studies that included more than 23,000 women.
Based on their analysis, the researchers estimate that endometriosis is associated with a threefold chance of developing clear-cell cancer, and more than double the risk of developing endometrioid tumours.
The researchers also said that their study is the first to establish a link between endometriosis and low-grade serous cancers, with the researchers finding a twofold risk.
In their study, the researchers caution that despite their findings, "most women with endometriosis do not develop ovarian cancer." However, doctors should be aware of the potential increase in risk among their patients with a history of endometriosis.
In women with the condition, cells that line the uterus grow in other parts of the body, including the ovaries, bowel, bladder or around the pelvis.
Endometriosis can be very painful and cause severe cramping during menstruation, as well as abdominal pain or back pain before and after a woman gets her period. Pain can also occur during sex or a bowel movement, and lead to fertility problems.
Experts believe the cells travel outside the uterus during menstruation, via the fallopian tubes.
Dr. Steven Narod of the Women's College Research Institute said the study "shows beyond any doubt women with endometriosis are at risk of ovarian cancer."
He told CTV News that the risk is still low, and so the findings "should not cause panic."
But it does raise the question for doctors about whether to classify women with endometriosis "to be at high risk of ovarian cancer."
"And," he added, if so, "what should we do?"
In a comment accompanying the study, Charlie Gourley of the University of Edinburgh Cancer Research UK Centre, writes that although the risk demonstrated by the study "is perhaps not in itself sufficient to justify targeted ovarian-cancer screening of patients with a history of endometriosis, the fact that some of the associated histological subtypes (eg, clear-cell) predominantly present at an early stage…makes this a consideration."
Study co-author Dr. Celeste Leigh Pearce, of the University of Southern California Los Angeles, agrees, saying that the findings may help doctors better identify their patients who are at greater risk of developing ovarian cancer, which could lead to more individualized prevention and detection strategies.
Ovarian cancer is difficult to detect in its early stages and, according to Pearce, scientists have yet to develop adequate screening programs for the disease.
Pearce told CTV News that research that is still ongoing is investigating whether increased screening offers any kind of benefit, and those results are expected later this year.
While they aren't sure why endometriosis may lead to cancer, the researchers hope to figure that out with further study.
Pearce said women who have an increased risk for disease can talk to their doctor about preventive strategies, which range from taking oral contraceptives -- which have been proven to offer some protective benefit against ovarian cancer -- to surgery to remove the fallopian tubes and ovaries.
"If you look at the complete body of research on endometriosis and ovarian cancer it does definitely look like endometriosis is a precursor lesion for ovarian cancer," Pearce told CTV.
"And with that knowledge now we can do work in the laboratory to understand how it goes from a benign gynaecological condition into a cancer, and with that info we can develop new treatments and new approaches to screening."
The study was conducted by a team from the Ovarian Cancer Association Consortium (OCAC), which is comprised of more than 40 groups of researchers from around the world who are looking at ovarian cancer and the factors that affect a woman's risk of developing the disease.
With a report from CTV's medical specialist Avis Favaro and producer Elizabeth St. Philip