Endometrioid ovarian cancer is one of the more common ovarian cancer subtypes after high-grade serous, and it often carries a more hopeful outlook because it is frequently caught early and tends to be low grade. Like clear cell cancer, it is linked to endometriosis — and its CA125 levels can be variable, so a normal result is not a guarantee that all is well.

What it is and how common it is

Endometrioid carcinoma is named because its cells resemble the lining of the uterus (the endometrium). It makes up a meaningful minority of ovarian cancers. Like clear cell cancer, it is associated with endometriosis, and the two subtypes share some of the same molecular features, such as ARID1A mutations.

Two other associations are worth knowing. First, endometrioid ovarian cancer sometimes occurs alongside a separate endometrial (uterine) cancer — when both are present and each looks independent, they are often two primary cancers rather than one spreading to the other. Second, endometrioid cancers are among the ovarian cancers linked to Lynch syndrome, an inherited condition that raises the risk of several cancers; a diagnosis can be a reason to consider genetic counseling.

Encouragingly, endometrioid ovarian cancer is frequently diagnosed at an early stage and is often low grade, both of which tend to mean a better prognosis.

How it behaves on a CA125 test

CA125 in endometrioid ovarian cancer is variable. It can be raised, but it may also be normal — particularly when the cancer is small and early stage, which is common for this subtype. As with clear cell cancer, women who have endometriosis may have a mildly elevated CA125 from the endometriosis itself, which further muddies the picture.

The message is consistent across these under-recognized subtypes: CA125 is one piece of information, not a verdict. It is interpreted alongside symptoms and imaging, and no single normal reading should override a persistent concern.

Symptoms and how it’s diagnosed

Endometrioid cancer shares the common symptoms of ovarian cancer, and — because of the uterine connection — abnormal bleeding can sometimes be part of the picture:

Persistent bloating or abdominal discomfort
Pelvic pain or pressure
Abnormal vaginal bleeding, particularly after menopause
Feeling full quickly or changes in appetite

Diagnosis relies on pelvic examination and imaging — transvaginal ultrasound plus CT or MRI as needed. Because of the association with uterine cancer, the endometrium may also be evaluated. If Lynch syndrome is suspected — for instance because of a personal or family history of related cancers — tumor testing and genetic counseling may be offered. A definitive diagnosis comes from a pathologist examining tissue removed at surgery.

Treatment and outlook

Surgery is the foundation of treatment. Because endometrioid cancer is often found early and low grade, surgery alone may be sufficient for some people, while others receive chemotherapy (usually platinum-based) depending on stage and grade. When the tumor is hormone-receptor positive, hormonal therapy is sometimes an option, particularly for low-grade or recurrent disease.

The outlook for endometrioid ovarian cancer is often relatively favorable compared with high-grade serous disease, especially for early-stage, low-grade tumors that are completely removed. As always, stage and grade at diagnosis are the strongest drivers of prognosis, and your care team can give guidance specific to your situation.

Questions to ask your care team

Is my cancer confirmed as endometrioid type, and what grade is it?
Should I be evaluated for a separate uterine (endometrial) cancer?
Given my diagnosis, should I consider genetic counseling for Lynch syndrome?
Was my tumor tested for hormone receptors?
Based on my stage and grade, do I need chemotherapy, or is surgery enough?

Why this matters to us

Endometrioid cancer shows that an ovarian cancer diagnosis is not always the worst-case story — but getting there still depends on looking past a reassuring blood test. The Cure Ovarian Cancer Foundation funds research and supports families across every subtype, common and rare. If this guide helped you, please consider donating so we can keep these resources free for the next person who needs them.

This page is for education and awareness and is not medical advice. Please bring your questions to your own care team, who know your situation best.