Endometriosis does not seem to significantly affect ovarian cancer prognosis and survival in patients of reproductive age, a small study suggests.
However, more research is needed to identify factors associated with the progression of endometriosis to cancer and also to identify women who would benefit from more aggressive endometriosis treatment.
The study, “Endometriosis-associated ovarian cancer is not a distinct clinical entity among young patients: A 12-year cohort study,” was published in the European Journal of Surgical Oncology.
Ovarian cancer risk factors include a number of variables, such as age, weight, menstrual history, pregnancy history, smoking, inheritance of certain mutations, and benign gynecological conditions, including endometriosis.
Specific risk incidences vary depending on the type of cancer, but according to a study published in The Lancet, overall, endometriosis was estimated to increase ovarian cancer risk by nearly 50%.
However, it remains unclear whether there is a meaningful clinical difference between ovarian cancer in a person with endometriosis (endometriosis-associated ovarian carcinoma, EAOC) and the same type of cancer in a person without endometriosis (non-endometriosis-associated ovarian cancer, non-EAOC).
This is of particular interest in younger individuals, since age itself is independently associated with different ovarian cancer prognoses (younger age seems to be a prognostic factor for improved survival). Moreover, endometriosis is most common in people between 25 and 35 years old, according to the authors of the study.
The researchers analyzed medical records of people 40 years of age or younger who were treated for ovarian cancer at the Peking Union Medical College Hospital in China between 2006 and 2017.
Specifically, the researchers compared cases of EAOC, comprising either ovarian endometrioid carcinoma (OEC) or ovarian clear cell carcinoma (OCCC), with non-EAOC cases.
The studied group included 94 people with ovarian cancer — 40 with endometriosis (EAOC group) and 54 without (non-EAOC group). All of them were treated surgically; most also received chemotherapy.
In terms of outcomes, “a total of 77 (81.9%) patients were alive with no evidence of residual tumour at the time of the last visit, 4 (4.3%) patients were alive with the recorded disease, and 13 (13.8%) were dead of the recorded disease. There were no obvious differences between the two groups in terms of these variables,” the researchers wrote.
Further statistical analyses demonstrated that endometriosis was not significantly associated with an altered risk of disease progression or death. Another factor was, most notably, whether there was residual disease after initial treatment.
On the whole, there were “no differences in clinicopathological [disease-causing] or prognostic features,” between ovarian cancer in people with or without endometriosis, according to the researchers.
There was one exception: painful periods, or dysmenorrhea, which was reported by a much higher percentage of people with endometriosis than without (45% vs. 3.7%). But, the researchers said, this “is a typical symptom of patients with endometriosis,” and, as a result, most likely isn’t tied to the ovarian cancer.
This was a fairly small study of patients treated at a single center, so the results shouldn’t be generalized yet — there is still a need for further research to understand both endometriosis and ovarian cancer, and the intersection of both diseases.
“Endometriosis is not an independent prognostic predictor in patients with OCCC and OEC when age is confined to under 40 years. It is premature to consider ovarian cancers arising from endometriosis as a distinct entity,” the researchers concluded.
“This analysis also suggests that reproductive-aged women with early-stage OEC and OCCC should be offered conservative treatment,” they said. “Future research should focus on the identification of factors that are associated with the malignant transformation of endometriosis and how to identify women for whom more definitive endometriosis treatment would be appropriate to prevent ovarian cancer.”