(HealthDay News) — A history of endometriosis increases the risk of developing ovarian cancer, although the increased risk is restricted to specific subtypes of invasive ovarian cancer, according to a meta-analysis published online Feb. 22 in The Lancet Oncology.
Celeste Leigh Pearce, Ph.D., from the University of Southern California in Los Angeles, and colleagues pooled data from 13 case-control studies, including 13,226 controls and 7,911 women with invasive ovarian cancer, to assess the association between endometriosis and histological subtypes of ovarian cancer.
The researchers found that 818 of the controls and 738 women with ovarian cancer reported a history of endometriosis. Women with borderline ovarian cancer were also included in the analysis, and 168 of 1,907 reported having endometriosis. Self-reported endometriosis correlated with a significantly elevated risk of clear-cell ovarian cancers (20.2 percent of cases versus 6.2 percent of controls; odds ratio [OR], 3.05); low-grade serous ovarian cancers (9.2 percent of cases; OR, 2.11); and endometrioid invasive ovarian cancers (13.9 percent of cases; OR, 2.04). There was no correlation seen between endometriosis and the risk of mucinous ovarian cancer (OR, 1.02; P = 0.93), high-grade serous invasive ovarian cancer (OR, 1.13; P = 0.13), or borderline serous or mucinous tumors (OR, 1.20; P = 0.12 and OR, 1.12; P = 0.45, respectively).
“Clinicians should be aware of the increased risk of specific subtypes of ovarian cancer in women with endometriosis,” the authors write.