Uterine corpus cancer

Histological classification

Epithelial neoplasms of the uterine body feature a variety of histological forms. The most common variant is endometrioid adenocarcinoma. In modern pathologic anatomy, it is customarily subdivided by molecular profile into the following subtypes:

• Tumors with POLE gene ultramutation.
• Neoplasms with impaired DNA mismatch repair system (MMR deficiency).
• Variants associated with p53 gene mutations.
• Tumors lacking a specific molecular profile.

In addition to the endometrioid variant, the classification also includes other histological types: serous, clear cell, mucinous and squamous cell carcinoma. Clinical practice also encounters mixed adenocarcinomas, malignant carcinosarcomas, and carcinomas of varying degrees of differentiation, up to undifferentiated forms.

Morphological structure and malignancy grading

At the microscopic level, adenocarcinoma can form diverse tissue patterns. Depending on the architectural structure of the parenchyma, the following are distinguished:

• tubular (consisting of tubular elements);
• trabecular (forming trabecular interlacing networks);
• alveolar;
• papillary (in the form of branching papillae);
• cystic structures.

The grade of malignancy of the neoplasm is typically assessed using the 1989 FIGO grading system. It is based on the severity of tissue and cellular atypia, dividing tumors into three groups:

1. G1 — well-differentiated carcinoma, the cells of which retain resemblance to normal epithelium.
2. G2 — moderately differentiated carcinoma.
3. G3 — poorly differentiated carcinoma, possessing the highest aggressive potential and having lost the characteristic features of the original tissue.

Clinical and morphological staging

Determination of the disease stage is carried out using the TNM (8th edition, 2017) and FIGO systems. Historically, there is a division into two FIGO systems, which are applied depending on available data.

Clinical classification (FIGO, 1971) is relevant for patients at the preoperative diagnostic stage or in cases where surgical intervention is impossible:

• Stage 0: non-invasive carcinoma (in situ).
• Stage I: the tumor process is strictly confined to the uterine body.
• Stage II: the neoplasm spreads to the cervix but does not extend beyond the organ.
• Stage III: tumor spread is confined within the lesser pelvis.
• Stage IV: invasion into adjacent organs or extension beyond the pelvic boundaries (IVA — invasion into the rectum or urinary bladder, IVB — presence of distant metastatic foci).

Morphological classification (FIGO, 1988/2009) requires a detailed evaluation of surgical material and histological data:

• IA: the lesion is localized exclusively within the endometrium.
• IB: the tumor invades the myometrium, involving no more than half of its thickness.
• IC: the depth of invasion into the muscular layer exceeds half of its thickness.
• IIA: the tumor involves the glandular apparatus of the cervix.
• IIB: deep invasion into the cervical stromal tissue is observed.
• IIIA: invasion of the uterine serosa, involvement of the fallopian tubes or ovaries, as well as the detection of malignant cells in peritoneal washings.
• IIIB: the tumor process extends to the vaginal walls.
• IIIC: metastatic involvement of the lumbar or pelvic lymph nodes is recorded.
• IVA: invasion into the mucosa of the rectum or urinary bladder.
• IVB: appearance of distant metastases, including involvement of inguinal lymph nodes.

Class and exam questions

What else to study on this topic

• Molecular profile of endometrioid adenocarcinoma (POLE, MMR, p53)
• Pathogenesis of glandular metaplasia and the influence of estrogens
• Features of lymphogenous and hematogenous metastasis
• Comparison of the TNM and FIGO staging systems

Other topics in the "Additional Topics" section

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