Endometriosis and breast cancer- love or hate?

GWAS studies of endometriosis show a decreased risk of breast cancer risk.

Key Points

Highlights:

• If endometriosis has genetic roots, then a reduced breast cancer risk might be compatible.

Importance:

• The Mendelian randomization study found a fundamental relationship between genetically predicted endometriosis and a decreased risk of overall breast cancer, as well as a lower risk for estrogen receptor-positive breast cancer.

What's done here:                            

• Mendelian randomization design was used to explore the causal relationship between genetically predicted endometriosis and breast cancer risk.
• The authors selected Instrumental variables from breast cancer data with a significant relationship with endometriosis at the genome-wide level.
• The data related to endometriosis was obtained from the FinnGen project, including 2953 endometriosis cases and 68,969 control participants.
• Breast cancer data was from the Breast Cancer Association Consortium dataset, with a total of 122,977 cases and 105,974 controls.

Key Results:

• Each standard deviation increase in endometriosis predicted a 5.0% decrease in breast cancer risk.
• In the subtype analysis, each standard deviation increase in endometriosis predicted a decrease in the risk of ER (+) breast cancer by 8%.
• No causal relationship was observed in estrogen receptor-negative type breast cancer patients.
• These findings provide evidence of an association between endometriosis and reduced breast cancer risk, with the strongest correlation observed in ER+ breast cancer.

Limitations:

• The study focused on genetically predicted endometriosis and its causal relationship with breast cancer risk, but it may not capture the full complexity of the relationship between these two conditions.

Lay Summary

Many studies have been conducted to investigate the relationship between endometriosis and breast cancer, but no definitive conclusion has been reached yet.

In the study co-authored by Yan and Li et al, endometriosis-related GWAS data was used to determine the causal relationship between breast cancer risk and endometriosis (EMS). The study used a Mendelian Randomization approach to conduct the analysis.

The results showed that for every standard deviation increase in endometriosis, the risk of breast cancer decreased by 5.0%. Estrogen Receptor negative breast cancer was not associated with a causal relationship. The study also looked at potentially confounding factors such as obesity and smoking to exclude the possibility that the causal inference could be affected by these factors.

This study has several strengths. The first-time use of MR analysis, the exclusion of possible confounding factors, and the use of published GWAS data are all strengths. The study is limited in clinical application, there is a weak protective effect observed and the study population is restricted to European ancestors.

In conclusion, this study provides evidence that Endometriosis is associated with a reduced risk of breast cancer.

Research Source: https://pubmed.ncbi.nlm.nih.gov/37828053/