Authors and Disclosures
Endometriosis and Cancer Risk
Women with endometriosis appear to be more likely to develop certain types of cancer. What scientists know about the link — and why it might occur — were the focus of a session at the inaugural symposium of the Endometriosis Foundation of America.
“We’ve got pretty good evidence that there’s some increase in the risk for ovarian cancer” with endometriosis, said Louise Brinton, PhD, Chief of the Hormonal and Reproductive Epidemiology branch at the National Cancer Institute, in an interview with Medscape following the session. “But there are still other cancers that need further study.”
Dr. Brinton’s interest in the long-term effects of endometriosis led her to Sweden about 20 years ago. Using the country’s national inpatient register, she identified more than 20,000 women who had been hospitalized for endometriosis. After an average follow-up of more than 11 years, the risk for cancer among these women was elevated by 90% for ovarian cancer, 40% for hematopoietic cancer (primarily non-Hodgkin’s lymphoma), and 30% for breast cancer. Having a longer history of endometriosis and being diagnosed at a young age were both associated with increased ovarian cancer risk.
“We found an increased risk for tumors with increasing years of follow-up,” said Dr. Brinton, “making it unlikely that the ovarian cancer diagnoses were related to increased surveillance during endometriosis treatment.” Also of special interest was the finding that “women whose site of origin of endometriosis was the ovary … had a particularly high risk for ovarian cancer.”
Dr. Brinton and colleagues published their research in 1997. A larger, more recent examination of the Swedish register, published in 2006 by Anna-Sofia Melin and colleagues, produced similar results.