Endometriosis is a chronic inflammatory disease caused by the growth of the endometrium (lining of the uterus) outside the uterine cavity. This disease affects 11% women of childbearing age according to a study published in 2011 in the journal Fertility and Sterility.
To learn more about how endometriosis subtypes (see box below) affect ovarian cancer risk, 450,906 medical records of women living in Utah, United States (78,476 with and 372,430 without) aged 18 to 55 were studied. These records were drawn from the Utah Population Database (UPDB).
Subtypes of endometriosis
Deep endometriosis:
When the endometrium (mucosa lining the uterus) grows elsewhere than in the uterus, an inflammatory reaction can take place and create lesions more than 5mm deep which can affect neighboring organs.
Ovarian endometrioma: An ovarian endometrioma is a type of ovarian cyst related to endometriosis.
Superficial peritoneal endometriosis: specific form of endometriosis that affects the peritoneum (membrane that covers the abdomen, including the wall and the organs it contains, except the ovaries).
4.20 times greater overall risk of developing ovarian cancer
The results, published on July 17, 2024 in the journal Jama, are consistent with previous observations: women with endometriosis have a higher risk than others of being affected by ovarian cancer, regardless of the histotype (the type of tissue appearing during the growth of a tumor).
The researchers found that people with endometriosis have an overall 4.20 times greater risk of developing ovarian cancer, including a 7.48 times greater risk of developing stage I ovarian cancer, and a 2.70 times greater risk of developing stage II cancer.
Type II cancer tends to be a more aggressive ovarian cancer, detected later, and associated with higher mortality compared to type I.
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Deep endometriosis causes a 19 times higher risk
This result is even more striking in some women. Thus, " People diagnosed with deep infiltrating endometriosis and/or ovarian endometriomas had a 9.66 times higher risk of ovarian cancer than people without endometriosis,” according to researchers.
And this risk differs depending on the stage (type I or II) of cancer. Women with deep infiltrating endometriosis and/or ovarian endometriomas had the highest risk of type I ovarian cancer, almost 19 times greater risk than women without endometriosis. Regarding type II cancer, these people have " four times more risk” to develop one than women without endometriosis. Superficial peritoneal endometriosis was associated with a risk 2.82 times higher for type I and 2.62 times higher for type II.
The results of this study are however limited, even underestimated. Indeed, there are few biomarkers – measurable biological characteristics – allowing the diagnosis of endometriosis, and also few diagnoses of endometriosis in women with no symptoms or no access to care.
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