Extra-ovarian malignancies risk among women with endometriosis

What are the risk of endometrial, thyroid, cervical, melanoma, and breast cancer in women with endometriosis?

Key Points

Highlight:

• This article is a meta-analysis to examine the risk of extra-ovarian malignancies in women with endometriosis.

Importance:

• The association between endometriosis and subsequent clear cell or endometrioid ovarian cancer has been reported. However, the association of endometriosis with other types of cancer is not clear.

What's done here:

• A meta-analysis study including 32 published data between 1989 and 2018 to assess the risk of extra-ovarian malignancies among women with endometriosis.
• Data were presented as a summary relative risk (SRR) and 95% confidence intervals (CI) calculated through random effect models.

Data:

• Increased risk of endometrial (SRR 1.38, 95%CI 1.10–1.74) and thyroid cancer (SRR 1.38, 95%CI 1.17–1.63) among women with endometriosis.
• An inverse association with cervical cancer (SRR 0.78, 95%CI 0.60–0.95).
• No association found for breast cancer (SRR 1.04, 95%CI 0.99–1.09) and melanoma (SRR 1.31, 95%CI 0.86–1.96).

Limitation:

• The heterogeneity between the studies was large for breast, endometrial cancer, and melanoma.

Lay Summary

For some time, an association between endometriosis and subsequent cancer risk have been reported. In particular, scientific evidence has shown that endometriosis is linked with risk of certain ovarian cancer subtypes known as clear cell and endometrioid. Since endometriosis is influenced by the female hormone, most studies have mainly examined the risk on malignancies related to the female reproductive system such as the ovarian, endometrial and cervical cancer, or cancers in which estrogen has been suggested including melanoma, breast etc. However, currently, the association between endometriosis and extra-ovarian malignancies is less clear. This article by Gandini et al. from Department of Experimental Oncology, European Institute of Oncology IRCCS, Milan, Italy aimed to conduct a systematic review and meta-analysis of studies which examined the relationship between endometriosis and extra-ovarian malignancies.

The authors searched these published reports in MEDLINE, EMBASE, Science Direct, and the Grey Literature Report websites. The three strings used were: “endometriosis AND cancer”, “endometriosis AND malignancy”, and “endometriosis AND tumour”. A total of 32 papers were then included in this meta-analysis. Studies were conducted between 1989 and 2018 in thirteen different countries.

This analysis found a significant increased risk of endometrial and thyroid cancer in women with endometriosis. In addition, there was an inverse association with cervical cancer risk. There was no association between endometriosis and the risk of breast cancer or melanoma risk.

While the data presented may be important, it should be viewed with caution because of the limitation of the study. Being a meta-analysis study, there was large variability in terms of study design, methods for exposure definition, statistical methods, and other important characteristics which may affect results obtained. Hence, the heterogeneity between the 32 studies must be considered.

Research Source: https://www.ncbi.nlm.nih.gov/pubmed/30771877