Endometriosis and Ovarian Cancer Risk

Ovarian cancer prevalence in women with endometriosis is higher than the general population.

Key Points

Highlight:

• Endometriosis may be a risk factor for ovarian cancer, although it is considered rare and affects approximately 1% of ovarian endometriomas.

Importance:

• There are reported correlations between endometriosis and ovarian cancer according to histology.
• Epidemiological evidence, however, is insufficient to suggest endometriosis as a cause of ovarian cancer to initiate changes to clinical practice.

What's done here:

• This systematic review article summarizes new knowledge and insights about the malignant transformation of endometriosis.
• Related epidemiological, histopathological, and molecular data presented.
• Besides, the author`s retrospective study in 33 patients diagnosed with ovarian cancer presumably from endometriomas summarized to understand the link between endometriosis and ovarian cancer.

Data:

• It is still not well validated that endometriosis may be the precursor of ovarian cancer.
• However, endometriomas should be carefully monitored clinically to identify subsets of women at higher risk of ovarian cancer.
• From the recent retrospective study, the author observed that ovarian cancer developed in the ipsilateral (i.e., same side) ovary in six of the patients after cystectomy for endometrioma.

Limitations:

• Long-term prospective studies in patients with endometriosis will be required to detect the incidence of the malignant transformation to develop prevention, screening and treatment approaches for women with endometriosis.
• "Ovarian cancer" is not a single entity and only the related subtypes of ovarian cancer should be concerned which is not so evident in epidemiological studies.
• "Self-reported" endometriosis may be questionable regarding diagnostic value.

Lay Summary

Ovarian cancer prevalence in women with endometriosis is higher than the general population. It is often hypothesized that endometriosis-associated malignancies can occur from ovarian endometrioma.

This systematic review by Taniguchi highlighted new insights on the relationship between endometriosis and ovarian cancer. On top of describing potential etiology of endometriosis-associated ovarian cancer according to histological findings, this article presented information from other relevant studies. These include: (i) Shizuoka Cohort Study on Endometriosis and Ovarian Cancer Programme in Japan where approximately 0.72% patients with ovarian endometrioma developed ovarian cancer, (ii) a study in the United States of 12,193 infertile women showed 13 of 45 women with ovarian cancers had been associated with endometriosis, (iii) a meta-analysis including 7911 women with ovarian cancer suggesting the association between endometriosis and clear-cell and endometrioid types of ovarian cancer, (iv) Netherlands study suggesting the occurrence of ovarian cancer and ovarian borderline tumors in endometriosis, (iv) study in Japanese women showing ovarian cancer developed in the ipsilateral ovary of six out of 33 patients after cystectomy for endometrioma, (v) other studies warning that endometrioma excision did not prevent the development of ovarian cancer, and that ovarian cancer can develop after cystectomy of endometrioma and more likely to occur from recurrent endometrioma, and (vi) studies showing that oophorectomy may have protective effect against development of ovarian cancer.

Overall, these data suggest an increased risk of certain subtypes of ovarian cancer in endometriosis. However, there is a lack of prospective studies assessing the relationship between endometriosis and ovarian cancer. Hence, the exact rate of malignancy as a result of endometriosis is unknown and current knowledge is insufficient to change clinical practice.

"A precise strategy should be set up for better prevention, early detection, specific diagnosis and treatment targeting molecular pathogenesis to understand the mechanisms of endometriosis-associated ovarian cancer. Endometriomas should be carefully monitored to identify subsets of women at higher risk of ovarian cancer. Clinicians need to be aware of the increased ovarian cancer risk in women with endometriosis." concluded Dr.Taniguchi.

Research Source: https://www.ncbi.nlm.nih.gov/pubmed/28718209