Endometriosis/Adenomyosis Status Not an Independent Predictor of Survival in Endometrial Cancer

Although patients with endometrial cancer who had histologically confirmed endometriosis/adenomyosis achieved better overall survival than those without, the benefit was linked to stage, grade, age, and histological subtype.

Endometriosis/adenomyosis status did not appear to be an independent prognostic factor for survival in endometrial cancer despite these patients appearing to have higher overall survival (OS) vs those without (P <.005), according to a study published in the International Journal of Cancer.

Those with endometrial cancer and endometriosis/adenomyosis tended to be younger at the time of diagnosis with earlier disease stage, endometrioid histology, and low-grade tumors. The 5-year OS rates for the endometriosis/adenomyosis cohort was 84.8% (95% CI, 84.6%-88.1%) vs 71.6% (95% CI, 71.1%-72.0%) for the non–endometriosis/adenomyosis cohort (HR, 0.63; 95% CI, 0.59-0.69). Significant confounding factors included age, stage, disease subtype, histologic grading, surgery, and chemotherapy rate (HR, 0.98; 95% CI, 0.90-1.06).

“We found an increased survival in women with endometrial cancer and histological proven endometriosis or adenomyosis. The increased prognosis seems large due to a younger age at endometrial cancer diagnosis, an earlier disease stage, a more favorable histological subtype and more low-grade tumors with higher surgery rate and lower chemotherapy rate in the group of women with endometrial cancer and endometriosis/adenomyosis. Future studies should study the exact mechanism for these more favorable tumor characteristics,” the investigators reported.

The retrospective analysis included patients with epithelial endometrial cancer who had been diagnosed from 1990 to 2015. The control group consisted of patients with endometrial cancer who did not have histologically confirmed endometriosis/adenomyosis. Investigators excluded individuals who were diagnosed with endometriosis/adenomyosis over half a year after their cancer diagnosis.

A total of 41,001 patients were eligible for the analysis, of whom 1755 had endometrial cancer and endometriosis/adenomyosis. Investigators reported that 161 patients had been excluded from the population, including 114 patients without epithelial histology and 47 who received their endometriosis or adenomyosis diagnosis half a year after their cancer diagnosis. The final population included 40,840 patients, of whom 4.2% had histologically proven endometriosis or adenomyosis.

A total of 1236 and 320 patients had adenomyosis and endometriosis, respectively. Among these patients, 145 had both endometriosis and adenomyosis. The median age at endometriosis and adenomyosis diagnosis was 57 years and 61 years, respectively.

The majority of endometriosis/adenomyosis diagnoses (93.7%) were concurrent with the endometrial cancer diagnoses. In cohorts with and without endometriosis/adenomyosis, 40% and 44% of patients, respectively had adenocarcinoma not otherwise specified. Low grade cancers were present in 63% of patients with endometriosis, 57% with adenomyosis, 70% with both endometriosis and adenomyosis, and 52% of the control cohort. Additionally, surgery was more common in the endometriosis/adenomyosis cohort, although they received chemotherapy less often.

The median follow-up from endometrial cancer diagnosis to death, emigration, or end of study was 11 years for the endometriosis/adenomyosis group and 8 years for the control group. Survival differences between the endometriosis and adenomyosis cohorts were not statistically significant. The median OS was 20 years in the endometriosis/adenomyosis cohort compared with 13 years in the control cohort (P <.0005). Moreover, the 5-year OS rates were 82.5% (95% CI, 77.8%-86.2%), 87.2% (95% CI, 85.2%-88.9%), and 89.6% (96% CI, 83.4%-93.6%) in the endometriosis, adenomyosis, and endometriosis/adenomyosis cohorts, respectively.

A total of 35,542 patients were eligible for the analysis, as 5298 had been excluded for missing values. Investigators reported several hazard ratios for comparison of OS vs patients with neither endometriosis or adenomyosis, including 0.68 (95% CI, 0.57-0.82) in the endometriosis cohort, 0.65 (95% CI, 0.59-0.71) in the adenomyosis cohort, and 0.45 (95% CI, 0.33-0.61) in the endometriosis/adenomyosis cohort.


Hermens M, van Altena AM, van der Aa M, et al. Endometrial cancer prognosis in women with endometriosis and adenomyosis: a retrospective nationwide cohort study of 40 840 women. Int J Can. 2022;150(9):1439-1446. doi:10.1002/ijc.33907

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