# Endometrial Cancer

Endometrial cancer management hinges on diagnostic histology, extent of uterine and extrauterine disease, and molecular classification. Integrating MMR immunohistochemistry, POLE sequencing, and p53 testing refines hereditary-risk assessment, operative planning, prognosis, and systemic-treatment selection.

**Clinical question:** How should physicians integrate molecular testing, staging evaluation, surgery, and systemic therapy in endometrial cancer?

Updated: 2026-08-24T17:05:59.122544+00:00

## What matters in practice
- Obtain tumor molecular classification with MMR immunohistochemistry, POLE exonuclease-domain mutation testing, and p53 assessment; these define POLEmut, MMRd, p53abn, and NSMP molecular groups. [3][10]
- An abnormal MMR immunohistochemistry result should trigger hereditary-cancer evaluation because germline MMR mutations alter counseling and can change the appropriateness of conservative management. [3]
- Total hysterectomy, bilateral salpingo-oophorectomy, and lymph-node assessment remain the operative standard for patients undergoing surgical treatment; sentinel-node mapping is an established staging approach. [20][21]
- Use MRI principally for local uterine assessment and CT or PET/CT when evaluating suspected extrauterine, nodal, or distant disease; PET/CT does not replace surgical staging. [16][17]
- For platinum-pretreated recurrent or advanced disease, dostarlimab activity is substantially greater in MMRd than MMRp tumors, making MMR status a treatment-selection biomarker. [4]

## Confirm histology and establish the preoperative risk phenotype

Obtain tissue diagnosis first, then use pathology and imaging to plan definitive local therapy.

After endometrial carcinoma is identified on endometrial sampling, document histologic type and grade, then obtain tumor molecular profiling early enough to inform multidisciplinary planning. Histologic type, grade, myometrial invasion, lymphovascular space invasion, and stage remain core clinicopathologic risk variables, but molecular classification now materially refines risk stratification. [18][23]

Order MMR immunohistochemistry, POLE exonuclease-domain mutation testing, and p53 assessment on diagnostic material or the hysterectomy specimen. This practical sequence identifies the four clinically used molecular groups: POLEmut, MMRd, p53abn, and no specific molecular profile (NSMP). MMR immunohistochemistry can identify the MSI phenotype, while p53 immunohistochemistry is a surrogate for TP53 status. [3][10]

Treat abnormal MMR immunohistochemistry as both a tumor-classification result and a hereditary-cancer triage result. Prompt hereditary-cancer referral is particularly consequential in a younger patient considering progestin-based conservative treatment because a germline MMR pathogenic variant, with associated colorectal, uterine, and ovarian cancer risk, may favor definitive surgery rather than fertility-sparing management. [3]
- Record the molecular result in the operative and adjuvant-treatment discussion rather than reporting it as a separate ancillary pathology finding. [10][23]
- Do not infer favorable biology from endometrioid histology alone: POLE-mutated tumors have excellent outcomes, whereas TP53-mutated/copy-number–high tumors have poor prognosis. [18]
- Escalate hereditary-risk assessment when MMR immunohistochemistry is abnormal, particularly before a decision to defer hysterectomy. [3]

*Molecular classification elements that change risk assessment and clinical planning. [3][10][18]*

| Molecular group | Defining practical test result | Clinical implication |
| --- | --- | --- |
| POLEmut | Pathogenic POLE exonuclease-domain mutation [10][18] | Associated with excellent outcomes; incorporate into prognostic and adjuvant-risk discussion. [18] |
| MMRd | Abnormal MMR immunohistochemistry; identifies the MSI phenotype [3][10] | Refer for hereditary-cancer evaluation; predicts materially higher observed dostarlimab response in platinum-pretreated advanced/recurrent disease than MMRp status. [3][4] |
| p53abn | Abnormal p53 assessment used as a surrogate for TP53 mutation status [3][10] | Signals aggressive serous-like biology and poor prognosis; incorporate into risk-directed treatment planning. [18] |
| NSMP | No POLE pathogenic mutation, no MMR abnormality, and no p53 abnormality in the molecular classifier [10] | Use remaining histology, invasion, LVSI, and stage variables for risk stratification. [18] |

## Select imaging according to the staging question

Imaging should answer a specific operative-planning question, not substitute for surgical-pathologic staging.

Perform pelvic examination and pelvic ultrasonography as clinical-staging components. For suspected cervical stromal involvement or assessment of local uterine extent, MRI is the most reliable modality among MRI, transvaginal sonography, and diagnostic hysteroscopy for predicting cervical involvement. [6][19]

Use contrast-enhanced pelvic MRI, including diffusion-weighted sequences when relevant, to assess depth of myometrial invasion and local extension. Diffusion-weighted MRI is especially useful when gadolinium cannot be administered and when adenomyosis complicates assessment of myometrial invasion. [17]

Use CT when the primary concern is advanced disease with extrauterine extension, lymphadenopathy, or distant metastases. Reserve PET/CT primarily for metastatic nodal or distant-disease evaluation when that result may change surgical or systemic management; PET/CT has limited value for initial evaluation of early-stage disease and cannot replace surgical staging. [16][17]
- Do not use CT alone to determine depth of myometrial invasion or cervical stromal invasion; reported CT sensitivity and specificity for these local features are limited. [17]
- Interpret PET/CT cautiously in premenopausal patients and in benign endometrial conditions such as hyperplasia, polyps, and adenomyosis because physiologic or benign FDG uptake can confound early-stage evaluation. [17]
- If cervical involvement is uncertain and the result would alter hysterectomy planning, obtain MRI rather than relying on transvaginal ultrasonography alone. [19]

*Imaging selection by the clinical question in endometrial cancer. [16][17][19]*

| Clinical question | Preferred modality | Interpretive limitation or advantage |
| --- | --- | --- |
| Depth of myometrial invasion or local uterine extent | MRI; include diffusion-weighted imaging when contrast is contraindicated [17] | Diffusion-weighted and dynamic contrast-enhanced MRI have similar pooled sensitivity for myometrial-invasion assessment. [17] |
| Cervical stromal involvement | MRI [19] | MRI is the most reliable of MRI, transvaginal sonography, and hysteroscopy for predicting cervical involvement. [19] |
| Extrauterine spread or distant metastases | CT; consider PET/CT for metastatic nodal or distant disease [17] | CT is useful for advanced-disease evaluation; PET/CT is not a replacement for surgical staging. [16][17] |
| Early-stage primary tumor detection | Do not rely on PET/CT for initial local staging [17] | Limited spatial resolution and physiologic or benign FDG uptake reduce its early-stage utility. [17] |

## Plan surgery around resectability, nodal staging, and molecular risk

For operable disease, combine definitive uterine surgery with an intentional nodal-assessment strategy.

For patients selected for primary surgical treatment, total hysterectomy with bilateral salpingo-oophorectomy and lymph-node assessment is standard care. Surgical pathology then supplies the definitive stage and the invasion, LVSI, histologic, and molecular features used for postoperative risk assessment. [20][18]

Use sentinel lymph-node mapping as the nodal-assessment strategy when performed within an appropriate surgical-staging program. Its increasing adoption reflects the need to establish nodal status while avoiding a routine full lymphadenectomy approach in every patient. [20][21]

Integrate molecular classification into postoperative risk assessment rather than using anatomic factors alone. The 2023 FIGO framework incorporates aggressive histologic types and p53 abnormality, and molecular classification is now incorporated into contemporary FIGO-based multidisciplinary decision-making. [10][18][23]
- Ensure the operative plan specifies how nodal status will be assessed before surgery; do not treat nodal evaluation as an incidental intraoperative decision. [20][21]
- Use final pathology to reconcile preoperative grade and histology with definitive tumor type, myometrial invasion, LVSI, stage, and molecular group. [18][23]
- Discuss p53abn disease as a high-risk biologic pattern even when traditional clinicopathologic factors appear less concerning. [18]

*Primary-treatment decision framework. [18][20][21][23]*

| Decision point | Action | Information needed next |
| --- | --- | --- |
| Operable, apparently uterine-confined disease | Plan total hysterectomy, bilateral salpingo-oophorectomy, and lymph-node assessment. [20] | Final stage, nodal status, histology, invasion, LVSI, and molecular classification guide postoperative risk assessment. [18][23] |
| Nodal status required for staging | Use a sentinel lymph-node mapping strategy within surgical staging. [20][21] | Incorporate nodal findings into definitive stage and adjuvant planning. [18] |
| p53abn or aggressive histologic phenotype | Use molecularly integrated risk discussion rather than anatomy alone. [18][23] | Assess final stage and other high-risk pathologic features in a multidisciplinary setting. [18] |

## Restrict conservative treatment to carefully selected low-risk disease

Conservative management is an exception to definitive surgery and requires molecular and hereditary-risk assessment.

Fertility-sparing management is generally directed to stage IA, well-differentiated (grade 1) endometrioid endometrial carcinoma. Conservative protocols use oral or local progesterone therapy, but eligibility should be reassessed if molecular testing or hereditary evaluation identifies a germline MMR pathogenic variant. [5][3]

Before deferring hysterectomy, establish the extent of disease with pelvic examination and pelvic ultrasonography, and use MRI when local staging—including myometrial or cervical involvement—will determine whether conservative treatment remains appropriate. [6][17][19]

Counsel that an abnormal MMR result has implications beyond tumor response: it prompts hereditary-cancer referral and may alter the balance between time-limited fertility preservation and definitive risk-reducing surgery. [3]
- Limit consideration to stage IA, grade 1 endometrioid carcinoma rather than extrapolating conservative treatment to aggressive histologies or higher-risk local disease. [5]
- Complete MMR assessment before finalizing a progestin-based conservative plan in a young patient. [3]
- Use MRI when invasion depth or cervical involvement would change eligibility for conservative management. [17][19]

## Use MMR status to direct treatment discussion in recurrent or advanced disease

Molecular status is most immediately actionable in platinum-pretreated recurrent or advanced disease.

In recurrent or metastatic endometrial cancer with measurable disease, expected median survival has historically been approximately 12 to 15 months, supporting early reassessment of disease extent and biomarker-directed treatment options at recurrence. [12]

For patients with dMMR recurrent or advanced endometrial cancer previously treated with platinum, the PD-1 inhibitor dostarlimab demonstrated an objective response rate of 42.3% (95% CI, 31%-55%) in 104 patients. In the MMRp cohort, objective response was 13.4% (95% CI, 9.3%-20.1%) among 142 patients, making MMR status clinically discriminating when discussing expected immunotherapy activity. [4]

Do not select niraparib or niraparib plus dostarlimab as a presumed synergistic strategy based on the reported phase II study: the combination did not demonstrate synergistic activity, and homologous-recombination-repair gene status in circulating tumor DNA was not significantly associated with clinical outcome. [4]
- Confirm MMR status in every patient being evaluated for systemic therapy for recurrent or advanced disease. [4]
- Use cross-sectional imaging to define nodal and distant disease before committing to a local versus systemic recurrence strategy. [17]
- Interpret ctDNA-detected homologous-recombination-repair alterations as investigational for treatment selection in this setting rather than as a validated predictor of niraparib benefit. [4]

*Biomarker-directed interpretation of reported systemic-treatment activity in platinum-pretreated recurrent or advanced endometrial cancer. [4]*

| Tumor biomarker | Reported dostarlimab objective response rate | Decision implication |
| --- | --- | --- |
| dMMR | 42.3% (95% CI, 31%-55%) in 104 patients [4] | Discuss PD-1 inhibitor therapy as a biomarker-supported option after platinum treatment. [4] |
| MMRp | 13.4% (95% CI, 9.3%-20.1%) in 142 patients [4] | Recognize lower reported monotherapy activity than in dMMR disease when setting treatment expectations. [4] |
| HRR status in ctDNA | No significant association with clinical outcome in the niraparib study [4] | Do not use ctDNA HRR status alone to predict niraparib benefit. [4] |

## References
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## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.