Endometriosis is a condition where tissue similar to the lining of the uterus grows outside the uterus. Multiple studies have shown that women with endometriosis have a higher risk of developing ovarian cancer compared to women without the condition. This association has been consistently observed across various populations and study design.
A recent study published in the USA examined the relationship between endometriosis and the risk for ovarian cancer.
The study found that individuals with endometriosis had a risk for ovarian cancer that was four times higher than that of women who did not have endometriosis.
Compared to women without endometriosis, those with endometriosis were over seven times more at risk of developing type 1 ovarian cancer, which included cancer types like endometrioid, clear cell, and mucinous.
Clear cell is a relatively rare subtype that accounts for about 5-10% of all ovarian cancers. Women with endometriosis have a significantly higher risk of developing this type.
Endometrioid is another subtype or about 10-15% of ovarian cancers. The risk for this type is also elevated in women with endometriosis.
Other studies report different magnitudes of risk such as a 2-3 times higher risk of ovarian cancer in women with endometriosis compared to those without. For example, a large pooled analysis of 13 case-control studies found that women with self-reported endometriosis had an odds ratio of 1.46 for all ovarian cancers, but this increased to 3.05 for clear cell ovarian cancer and 2.04 for endometrioid ovarian cancer.
Mechanisms that could precipitate the link between endometriosis and ovarian cancer are never having given birth and early menstruation. Other factors such as chronic inflammation, which can lead to DNA damage and promote cancer development, as well as genetic mutations found in endometriosis lesions are also seen in certain ovarian cancers, suggesting a potential common origin or progression pathway. Lastly hormonal factors such as estrogen might play a role in the causative association.
In conclusion, while the association between endometriosis and ovarian cancer is significant and scientifically established, it's important to maintain perspective on the overall risk. Women with endometriosis should be informed about this risk.
Ref :
https://www.medicalnewstoday.com/articles/149109 
