Endometriosis Increases Risk of Ovarian Cancer
Some subtypes of endometriosis can raise patients’ cancer risk as much as 19-fold
Michael Schubert, PhD, is a veteran science and medicine communicator. He holds graduate degrees in biochemistry and molecular biology with a research focus on chromatin structure and function and has written on subjects from subspeciality pathology to fictional science. In addition to writing and editing, he is co-director of the Digital Communications Fellowship in Pathology and Course Trainer at the Lightyear Foundation, an initiative aimed at making science accessible to all.
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Although the association between endometriosis and ovarian cancer risk is known, the relative risks conferred by different endometriosis subtypes were a mystery—until now. A recent study published in JAMA of almost 460,000 people has revealed that the risk of ovarian cancer is 4.2-fold higher in people with endometriosis than in those without.
Some types of endometriosis, however, conferred a much more significant increase in risk than others; study participants with deep infiltrating endometriosis or endometriomas (fluid-filled cysts that arise from the disease process) exhibited a 9.7-fold higher risk of ovarian cancer overall. These patients had 19 times the risk of developing type I ovarian cancer, which is typically less aggressive and includes clear cell, endometrioid, mucinous, and low-grade serous cancers; their risk of the more aggressive type II (high-grade serous) cancers was 3.7 times that of people without endometriosis.
The study sought to clarify confusion arising from previous research that relied on self-reported diagnoses of endometriosis and failed to consider the potential impact of surgical excision procedures. In addition, the authors wanted to elucidate the importance of screening people with endometriosis for ovarian cancer to ensure the disease is caught early. Currently, because ovarian cancers are often diagnosed late, their five-year survival rates remain well below those of other cancers including breast, uterine, and cervical cancer.
“Given the rarity of ovarian cancer, the excess risk was relatively small, with 10–20 additional cases per 100,000 women,” senior author Karen C. Schliep, associate professor of public health at the University of Utah School of Medicine, said in a recent press release. “Nevertheless, women with endometriosis, notably the more severe subtypes, may be an important population for targeted cancer screening and prevention studies.” Schliep and her colleagues also emphasize the need for a greater understanding of the biology underlying the association between endometriosis and ovarian cancer so that these mechanisms can contribute to potentially lifesaving improvements in prognosis, diagnosis, and treatment selection.