Endometriosis is a condition where the lining of the
uterus is found at sites outside the uterus, including the ovaries and the
pelvis. It could result in painful periods, pelvic inflammation and even
Endometriosis has been associated with a particular
type of ovarian cancer called invasive epithelial ovarian cancer. This type of
cancer can be of 5 types depending on the biopsy picture - clear-cell,
endometrioid, mucinous, high-grade serous, and low-grade serous.
A study was
carried out to assess which specific type of epithelial ovarian cancer is
associated with endometriosis. For the study, results of 13 previously published
case-control studies on this topic were analyzed. These studies were conducted
in Australia, United States and Europe.
The data was obtained from a total of 23, 144 women,
of which 7911women had invasive ovarian cancer and 1907 women had borderline
ovarian cancer. Other information regarding age, ethnic origin, parity,
breastfeeding, duration of oral contraceptive use, family history of ovarian
cancer, weight, height, and history of tubal ligation was also recorded.
In the study, 9.3% women with invasive epithelial
ovarian cancer and 8.8% women with borderline ovarian cancer had been diagnosed
When the invasive ovarian cancer patients with
endometriosis were classified according to types of cancer, it was found that
20.2% women had clear-cell cancer, 13.9% had endometrioid cancer, 6.0% had
mucinous cancer, 7.1% had high-grade serous cancer, and 9.2% had low-grade
serous type of cancer.
In women with borderline ovarian cancer and
endometriosis, 9% women had borderline serous and 8.5% had borderline mucinous
Conditions like breastfeeding, weight, height, body-mass
index, tubal ligation, and family history of ovarian cancer did not influence
the risk of ovarian cancer in patients with endometriosis.
The study found that endometriosis was not
associated with borderline ovarian cancer. It
was however associated with invasive epithelial ovarian cancer, especially
invasive low-grade serous, endometrioid, and clear-cell types.
A clearer understanding of the topic would help to
screen women with endometriosis regularly for early detection of specific types
of ovarian cancer.
1. Association between endometriosis and risk of histological subtypes
of ovarian cancer: a pooled analysis of case—control studies; Dr.Celeste Leigh
Pearce et al; The Lancet Oncology 2012. DOI:10.1016/S1470-2045(11)70404-1