ENDOMETRIOSIS is linked to ovarian cancer risk, but absolute lifetime risk remains low for most patients.
Endometriosis Ovarian Cancer Risk Is Histotype Specific
Endometriosis, particularly ovarian endometrioma, is associated with an increased risk of ovarian cancer, according to a new review synthesizing epidemiologic, molecular, diagnostic, and clinical evidence. The strongest associations were seen for clear cell and endometrioid ovarian cancers, the subtypes most closely linked to endometriosis associated ovarian carcinomas.
Despite this association, the review emphasizes that the absolute lifetime risk of ovarian cancer in women with endometriosis remains relatively low, estimated at 1.9%. This distinction is clinically important, as relative risk estimates may appear substantial while still translating into a low absolute probability for most patients.
Molecular Clues Point to Shared Pathways
The review highlights shared somatic mutations between endometriosis and selected ovarian cancer subtypes, including alterations in ARID1A, PIK3CA, and KRAS. These findings support a biologically plausible pathway from ectopic endometrial tissue toward malignancy in specific settings.
The ovarian microenvironment may be especially relevant. Ovarian endometriosis cysts contain high levels of free iron, which can promote oxidative stress, while local estrogen metabolism may contribute to DNA damage. Together, these factors may help explain why malignant transformation is more commonly linked to ovarian endometriomas than to extraovarian lesions.
Clinical Decision-Making Must Remain Individualized
Diagnosis and risk stratification remain challenging. Transvaginal ultrasound and MRI have improved the assessment of endometriosis and adnexal masses, but neither can reliably identify malignant transformation. Biomarkers such as CA-125 and HE4 may provide additional information, although limited specificity reduces their value in routine practice.
Long-term combined oral contraceptive use appears to offer meaningful protection against ovarian cancer in women with endometriosis, with benefit persisting for more than a decade after discontinuation. Surgical excision of ovarian endometriomas may also reduce risk, but must be weighed against recurrence, ovarian reserve loss, fertility goals, and quality of life.
The review does not support routine prophylactic salpingo-oophorectomy for endometriosis alone. Instead, it calls for personalized risk prediction models incorporating genetic, clinical, and environmental factors, alongside multidisciplinary care that balances cancer prevention with fertility preservation and patient-centered outcomes.
Reference
Leone Roberti Maggiore U et al. Endometriosis and ovarian cancer: epidemiological evidence, molecular insights, and clinical decision-making. Hum Reprod Update. 2026;doi:10.1093/humupd/dmag011.
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