Do Women With Endometriosis Subtypes Have Greater Ovarian Cancer Risk?

Researchers assessing a Utah-based cohort of women with and without endometriosis found that women with endometriosis had 4.2-fold higher risk of ovarian cancer compared with women without endometriosis. Further, when looking at endometriosis subtypes, women with ovarian endometriomas and/or deep infiltrating endometriosis had 9.7-fold higher risk of ovarian cancer compared with women without endometriosis.

Although the association between endometriosis and an increased risk of ovarian cancer is well known, the associations between endometriosis subtypes and ovarian cancer histotypes are not well understood.

Enter Barnard and colleagues, who developed a population-based cohort study using data from the Utah Population Database (UPD) to determine whether there are associations between endometriosis subtypes and incidence of ovarian cancer. They developed the cohort by matching 78,893 women with endometriosis in a 1:5 ratio to women without endometriosis.

Researchers used electronic health records to identify the endometriosis cases, which were then broken down into four categories: (1) superficial endometriosis, (2) ovarian endometriomas, (3) deep infiltrating endometriosis, and (4) other.

Among the cohort, the mean age at first endometriosis diagnosis was 36 years, and there was a total of 597 women with ovarian cancer. The results indicated that women with endometriosis were 4.2 times more likely to develop ovarian cancer than those without endometriosis (95% CI, 3.59 to 4.91). Additionally, women with endometriosis were 7.48 times more likely to develop type I ovarian cancer (95% CI, 5.80 to 9.65) and 2.7 times more likely to develop type II ovarian cancer (95% CI, 2.09 to 3.49) compared with women without endometriosis. Ovarian cancer risk was highest for women with deep infiltrating endometriosis and/or ovarian endometriomas. Indeed, women with deep infiltrating endometriosis had the highest risk of ovarian cancer, overall—9.66 times the risk compared with women without endometriosis (95% CI, 7.77 to 12.00).

“When endometriosis subtypes and ovarian cancer histotypes were evaluated together, the strongest association was between deep infiltrating endometriosis and/or ovarian endometriomas and type I ovarian cancer, although risks were elevated for all endometriosis subtypes for both type I and type II ovarian cancer,” Barnard and colleagues explained.

This study had limitations, most notably, that misclassification of endometriosis was possible due to the researchers not having a biomarker for diagnosis, temporal changes in the procedures available to diagnose subtypes, and the challenge in diagnosing endometriosis among women without symptoms or access to care.

“Ovarian cancer risk was markedly increased among women with ovarian endometriomas and/or deep infiltrating endometriosis,” the researchers concluded. “This population may benefit from counseling regarding ovarian cancer risk and prevention and could be an important population for targeted screening and prevention studies.”

Reference:
Barnard ME, Farland LV, Yan B, et al. Endometriosis typology and ovarian cancer Risk. JAMA. 2024;332(6):482-489. doi:10.1001/jama.2024.9210