How is endometrial cancer diagnosed ?
In cases of suspected endometrial cancer, the gynecologist will ask the patient about any symptoms she may be experiencing. They will inquire about the patient’s medical history and potential risk factors for cancer. The gynecologist will also ask if any family members have had benign conditions (fibroids, polyps, endometriosis) or malignant uterine diseases, as well as other types of cancer within the family.
A full clinical examination will be performed, including an assessment of the breasts, abdomen, and lymph node areas. A vaginal examination and rectal examination will be conducted to evaluate the reproductive organs and nearby structures such as the bladder and rectum. The presence of a mass in the uterus will raise concerns.
A Pap smear will also be performed. A transvaginal ultrasound may be conducted, possibly followed by a biopsy. A colposcopy, which allows examination of the vagina and cervix using a binocular magnifying device (colposcope), may also be prescribed. For women with recurring symptoms or when an abnormality in the endometrium is detected during the transvaginal ultrasound, a diagnostic hysteroscopy will be performed.
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Diagnostic hysteroscopy can be performed on an outpatient basis (without hospitalization). It is most often done under general anesthesia. The procedure involves inserting a thin optical instrument called a hysteroscope into the uterus after dilating the cervix. This instrument allows direct visualization of lesions, their localization, and guidance for biopsies.
Endometrial biopsies performed after a transvaginal ultrasound or diagnostic hysteroscopy enable the pathologist to determine the exact nature of the malignant tumor under a microscope (histological analysis). In more than 90% of cases, the cancer develops from endometrial cells, which is why the term endometrial cancer is almost synonymous with uterine cancer.
Malignant endometrial tumors
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There are several categories of endometrial cancer ( histological types ). The most common type is endometrioid adenocarcinoma , accounting for approximately 80% of cases. This cancer typically appears early after menopause, during the fifth or sixth decade of life.
It more often affects women with obesity, hypertension, or type 2 diabetes. It is also more frequent in women who had an early onset of menstruation, late menopause, or few or no pregnancies.
This type of cancer is usually diagnosed at an early stage, and the prognosis is favorable. Other types are classified as non-endometrioid cancers, accounting for about 20% of cases. These cancers tend to affect older, non-obese women in their seventh or eighth decade of life. They are often diagnosed at a more advanced stage and have a less favorable prognosis (source: arcagy.org).
Histological analysis also allows the pathologist to determine the tumor grade, which ranges from 1 to 3. The higher the grade, the more the appearance of cancer cells differs from normal cells, and the more aggressive the cancer cells are.
Determining the grade of a cancer
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Grade 1 cancers (well-differentiated cancers) have cells that appear relatively normal and multiply slowly. Grade 3 cancers (poorly differentiated cancers) have highly abnormal cells that multiply rapidly. Grade 2 cancers (moderately differentiated cancers) exhibit intermediate characteristics between grade 1 and grade 3 cancers.
If the suspicion of endometrial cancer is confirmed, additional tests will be performed before starting treatment. This pre-treatment evaluation often includes an MRI (Magnetic Resonance Imaging) to assess the depth of tumor invasion into the myometrium. This exam will also help determine any possible lymph node involvement and locate any potential spread of the disease beyond the uterus.
For patients with high-grade tumors (grade 3), a CT scan of the chest, abdomen, and pelvis will be performed to check for any metastases distant from the uterus.
For patients diagnosed before the age of 50 or those with a personal or family history (first-degree relatives) of colorectal, ovarian, stomach, small intestine, or biliary or urinary tract cancers, suggesting a Lynch syndrome (a genetic condition that increases the risk of certain cancers), the doctor will prescribe specific tests to determine if the tumor cells have genetic instability and microsatellite instability.
These tests are performed in a pathology laboratory on the tumor cells or in a molecular biology laboratory on the tumor DNA. They will help determine if the patient may potentially benefit from immunotherapy.
Genetic instability, microsatellite instability and MSI status
Expert perspective
When cells divide, the DNA of the daughter cells must be identical to that of the mother cell.
However, errors can occur during this division. Normal cells have a system to repair these errors (the MMR system , or MisMatchRepair ). This system functions through four key proteins: MLH1, PMS2, MSH2, and MSH6 .
Sometimes, one of these proteins is deficient, and the cell becomes unable to repair its DNA ( Mismatch Repair Deficiency , or MMR-D ). This deficiency can be sporadic or hereditary, leading to a condition known as Lynch syndrome .
This deficiency causes multiple mutations, and the cells with these defects are said to have genetic instability . These mutations often occur in highly repetitive DNA sequences called microsatellites . Cells with these multiple mutations in microsatellites are said to have microsatellite instability (MSI) . These mutations contribute to a stronger stimulation of the immune system.
As a result, patients with a tumor that has a deficiency in the repair system ( MMR-D tumor ) leading to genetic instability and microsatellite instability ( MSI tumor ) may benefit from immunotherapy (discussed further below). Therefore, it is important to determine the MSI status of a tumor , which involves assessing whether a tumor has a deficiency in the repair system, leading to genetic instability and microsatellite instability.
The tests conducted to establish the diagnosis and perform a pre-therapy assessment will help determine the stage of the cancer. This stage can also be determined after the surgical intervention and the histological examination of the various surgical specimens.
Determining the stage of cancer
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Determining the stage of cancer is primarily of therapeutic interest , as knowing the stage will help establish the most appropriate treatment for the patient. It will also predict the most likely progression of the disease ( prognostic interest ).
The stage of cancer is determined based on three criteria. The first criterion depends on the characteristics of the tumor ( T ); the second criterion depends on the number of affected lymph nodes N for Node ]; the third criterion depends on the presence of metastases and the number of organs affected by them ( M ). These three criteria help define the stage of cancer according to an internationally recognized classification ( TNM classification ).
Stage 1 cancers are tumors limited to the endometrium.
Stage 2 cancers are tumors that affect the cervix.
Stage 3 cancers are tumors that extend beyond the uterus, including those that invade the vagina but remain within the pelvic region.
Stage 4 cancers are tumors that reach the bladder or rectum or spread beyond the pelvic region.
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Article updated on Jan 23, 2025
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