Grant: Project Grant - Priority Announcement: Early Detection/Cancer Prevention

Endometriosis is a common chronic condition characterized by lesions resembling uterine tissue found outside the uterus. It affects 10% of people with uteruses and carries a 2 to 4-fold increased risk of two types of ovarian cancer, called clear cell and endometrioid ovarian cancers (herein referred to as -associated ovarian cancers). Research examining endometriosis-associated ovarian cancer has historically relied on a self-reported or clinical diagnosis of endometriosis, however the best diagnostic test for endometriosis is a pathologic diagnosis. We currently do not properly understand how common endometriosis treatments (surgical and hormonal treatments) impact risk for endometriosis-associated ovarian cancer. There is also a suggestion that endometriosis will take on atypical features, which can be identified by specialized gynecologic pathologists in the laboratory, prior to becoming cancer. However, there are few studies of the progression of endometriosis with atypical features over time. Given this uncertainty, no clinical guidelines exist and clinicians are unsure whether to act more aggressively to prevent cancer in these cases. We have built a unique dataset to address these unanswered questions. It includes all people with pathologically confirmed endometriosis in the Vancouver Coastal Health Authority in British Columbia, Canada (population ~1 million) between 2000 and 2008. These data have been linked with population-based administrative datasets in British Columbia, Canada, which includes all treatments received in the universal health care system in the province. We propose to use these data to reassess the association between endometriosis and ovarian cancer, to determine how the surgical and hormonal treatments for endometriosis influence risk for endometriosis-associated ovarian cancer, and to determine rates of endometriosis with atypical features in people who later developed cancer compared to those who never developed cancer.