FIGO Grading and Staging Guidelines for Endometrial Cancer

1. Histopathological Grading

• The FIGO histological grading system classifies endometrioid carcinoma into three grades based on the proportion of solid (non‑squamous, non‑morular) growth: Grade 1 ≤ 5 %, Grade 2 5–50 %, and Grade 3 > 50 %; notable nuclear atypia upgrades the tumor by one grade regardless of architecture【1】【2】【3】.
• When significant nuclear atypia is present, the tumor grade must be increased by one level (e.g., G1 → G2, G2 → G3) to avoid under‑treatment【1】【2】【3】.

Evidence level: Consensus guideline (no formal grading reported).

2. FIGO 2009 Staging System

• The FIGO 2009 surgical staging classification is the most widely used system for endometrial cancer【1】【3】.

Evidence level: Consensus guideline (no formal grading reported).

3. Risk Stratification and Adjuvant Therapy

• Approximately 75 % of patients present with Stage I disease, which is subdivided into three prognostic risk groups that guide adjuvant treatment【1】【2】【3】.

Low‑Risk Disease

• Criteria: Stage Ia or Ib, Grade 1‑2, endometrioid histology【1】【2】【3】.
• Management: No adjuvant therapy required after surgery【2】【4】.

Intermediate‑Risk Disease

• Criteria: (a) Stage Ic, Grade 1‑2, endometrioid; or (b) Stage Ia‑Ib, Grade 3, endometrioid【1】【2】【3】.
• Management: Adjuvant pelvic radiotherapy markedly reduces pelvic/vaginal recurrences but does not improve overall survival【2】【4】【5】. For patients ≥ 60 years with deeply invasive G1‑G2 or superficially invasive G3 tumors where locoregional relapse risk exceeds 15 %, adjuvant radiotherapy is recommended【4】.

High‑Risk Disease

• Criteria: (a) Stage Ic, Grade 3, endometrioid; or (b) any stage with serous, clear‑cell, small‑cell, or undifferentiated histology【1】【2】【3】.
• Management: Combined pelvic radiotherapy plus platinum‑based chemotherapy improves overall survival and progression‑free survival compared with radiotherapy alone【4】.

Evidence level: Mostly Level II–III (prospective cohort and randomized data for radiotherapy; chemotherapy benefit from randomized trials).

4. Surgical Management

• Standard procedure for all patients: Total hysterectomy with bilateral salpingo‑oophorectomy, peritoneal washings, and thorough abdominal exploration【1】【3】.
• High‑risk cases (Grade 3 or non‑endometrioid histology): Retroperitoneal lymph‑node dissection and omentectomy (particularly for serous carcinoma) are recommended, although the survival advantage remains debated【1】【3】.

Evidence level: Consensus guideline; survival benefit of extensive nodal surgery is uncertain (Level III).

5. Additional Independent Prognostic Factors

• Depth of myometrial invasion, histological type, tumor diameter, lymphovascular space involvement (LVSI), endocervical stromal invasion, and patient age are established independent prognostic variables that complement FIGO stage and grade【1】【2】【3】.

Evidence level: Observational studies (Level III).

6. Limitations of Pre‑operative and Intra‑operative Assessment

• Pre‑operative grading reliability: Up to 25 % of endometrial sampling diagnoses change after final pathology, making pre‑operative grade uncertain【1】【2】【3】.
• Frozen‑section assessment: No fully reliable method exists to determine an individual patient’s risk category intra‑operatively; decisions regarding lymphadenectomy should rely on pre‑operative risk assessment rather than frozen‑section findings【1】【2】【3】.

Evidence level: Retrospective analyses (Level III).

7. Special Histological Subtypes

• Serous and clear‑cell carcinomas are automatically classified as high‑risk irrespective of stage or grade and require aggressive treatment with chemotherapy and consideration of pelvic radiotherapy【1】【2】【3】【6】.
• Carcinosarcomas are now regarded as a poor‑prognosis subtype of endometrial carcinoma rather than a separate entity【1】【3】.

Evidence level: Consensus and retrospective cohort data (Level III).

Endometrial Cancer Staging and Treatment

Introduction to Endometrial Cancer Staging

• The International Federation of Gynecology and Obstetrics (FIGO) recommends surgically staging endometrial cancer using the FIGO 2009 system, which classifies disease based on myometrial invasion depth, cervical stromal involvement, and lymph node metastases, with treatment centered on total hysterectomy and bilateral salpingo-oophorectomy, followed by risk-stratified adjuvant therapy 7, 8

FIGO 2009 Staging System

• The FIGO 2009 staging system divides endometrial cancer into four main stages, with stage I being the most common, and is used to guide treatment decisions 7, 9
• Stage IA is characterized by no myometrial invasion or invasion to less than half of the myometrium, while Stage IB involves invasion equal to or more than half of the myometrium 7, 9
• Stage II involves cervical stromal invasion, Stage III involves local or regional spread, and Stage IV involves advanced disease with distant metastases 7, 9

Preoperative Evaluation

• The European Society of Gynecologic Oncology recommends a preoperative workup including endometrial biopsy, transvaginal ultrasound, and contrast-enhanced dynamic MRI to assess myometrial invasion and cervical stromal invasion 10, 8
• Laboratory tests, such as complete blood count and liver function tests, and a clinical and gynecological examination are also recommended 10, 8

Surgical Treatment Approach

• The American College of Obstetricians and Gynecologists recommends total hysterectomy with bilateral salpingo-oophorectomy as the cornerstone of treatment, with minimally invasive surgery preferred over laparotomy 11, 8
• The Society of Gynecologic Oncology recommends lymphadenectomy for intermediate-to-high-risk endometrioid cancer, but notes that routine systematic pelvic lymphadenectomy does not improve overall survival or disease-free survival in stage I endometrial cancer 7, 12, 13, 8

Risk Stratification

• The National Comprehensive Cancer Network recommends risk stratification based on stage, grade, and histology, with approximately 75% of patients presenting with stage I disease, which can be subdivided into three risk categories: low-risk, intermediate-risk, and high-risk 10, 9
• Low-risk disease is characterized by stage IA, grade 1-2, endometrioid histology, while intermediate-risk disease involves stage IB, grade 1-2, endometrioid histology, and high-risk disease involves stage IB grade 3, deep myometrial invasion, or non-endometrioid histology 10, 9

Adjuvant Treatment Framework

• The American Society for Radiation Oncology recommends external beam radiation therapy to reduce locoregional recurrence in intermediate-risk disease, but notes that it does not improve overall or disease-specific survival 7, 12, 13
• The American Society of Clinical Oncology recommends platinum-based chemotherapy for stage II-III disease, and notes that it should be considered for high-risk patients 7, 12, 13

Medically Inoperable Patients

• The European Society for Medical Oncology recommends external radiation therapy with or without intracavitary brachytherapy for medically inoperable patients, which is suitable for 5-10% of patients who are not candidates for surgery 7, 12, 13, 8

FIGO Grading and Staging of Endometrial Carcinoma

Grading of Endometrioid Tumors

• Grading assesses the microscopic architecture and cellular characteristics of the tumor itself, providing insight into biological aggressiveness. [14][15]

• The FIGO grading system is applicable primarily to endometrioid histology; serous, clear‑cell, and undifferentiated carcinomas are automatically classified as high‑grade irrespective of their architectural pattern. [14][15]16

Staging (Anatomical Extent)

• Staging determines the anatomical spread of endometrial carcinoma and is established through surgical evaluation, guiding therapeutic strategy. [14][15]16

• Stage II (FIGO):

  • IIa – Tumor involves only the endocervical glands.
  • IIb – Tumor invades the cervical stroma.

Integration with Additional Prognostic Factors

• Established independent prognostic variables (e.g., depth of myometrial invasion, tumor size, lymphovascular space involvement, patient age) are used to refine risk assessment when grade and stage alone do not fully inform treatment decisions. [14][15]

Evidence‑Based Diagnosis, Staging, and Management of Endometrial Carcinoma

Diagnosis and Pre‑operative Workup

• Obtain endometrial tissue by office‑based Pipelle biopsy or dilation and curettage (D&C) to establish a histologic diagnosis; D&C may yield more representative samples when Pipelle is inadequate. 17
• Perform a clinical and gynecologic examination to assess uterine size and possible cervical involvement. 17
• Use transvaginal ultrasound to evaluate endometrial thickness and depth of myometrial invasion. 17, 18
• Employ pelvic MRI with contrast enhancement as the most accurate imaging modality for determining myometrial invasion depth and cervical stromal involvement. 18
• Include complete blood count, liver‑function, and renal‑function panels in the pre‑operative laboratory work‑up. 17, 18
• Consider chest/abdominal CT or FDG‑PET‑CT in high‑risk patients (high‑grade tumor, non‑endometrioid histology, deep myometrial invasion) to detect extrapelvic disease. 17

Standard Surgical Treatment

• Perform total hysterectomy with bilateral salpingo‑oophorectomy as the cornerstone operation for all stages. 17, 18
• Prefer minimally invasive approaches (laparoscopic or robotic) over laparotomy; they provide equivalent oncologic outcomes with shorter hospital stays and fewer complications. 17
• Choose a robotic platform especially for patients with obesity, as it offers technical advantages in this subgroup. 17
• Conduct peritoneal washings and a thorough abdominal exploration at the start of surgery. 17, 18

Lymph‑Node Assessment

• Omit systematic lymphadenectomy in endometrioid FIGO IA, grade 1‑2 disease where the risk of nodal metastasis is < 5 %. 17
• Perform nodal evaluation (sentinel or systematic) in non‑endometrioid histology, FIGO IB disease, or grade 3 tumors. 17
• Use sentinel lymph‑node biopsy with indocyanine‑green dye as the emerging preferred alternative to full pelvic‑para‑aortic lymphadenectomy, offering high sensitivity for detecting metastases. 17
• Systematic pelvic lymphadenectomy does not improve overall survival in early‑stage disease, as demonstrated by randomized trials. 17, 18 (Level I evidence)

Special Surgical Considerations

• Perform omentectomy for carcinosarcoma and serous‑type endometrial carcinoma. 17
• Consider ovarian preservation in premenopausal patients with FIGO stage IA, grade 1 endometrioid cancer, provided there is no Lynch syndrome or germline BRCA mutation. 17

Risk Stratification and Adjuvant Therapy

Low‑Risk Disease (Stage IA, grade 1‑2 endometrioid)

• No adjuvant therapy is required after surgery. 18

Intermediate‑Risk Disease (Stage IB, grade 1‑2 or Stage IA, grade 3 endometrioid)

• Adjuvant pelvic radiotherapy markedly reduces pelvic/vaginal recurrence but does not improve overall survival. 18 (moderate‑quality evidence)
• Offer pelvic and/or vaginal brachytherapy to patients ≥ 60 years with deeply invasive grade 1‑2 or grade 3 tumors when the estimated locoregional relapse risk exceeds 15 %. 18

High‑Risk Disease (Stage IB, grade 3 endometrioid; any stage serous, clear‑cell, or carcinosarcoma)

• Combined pelvic radiotherapy plus platinum‑based chemotherapy (carboplatin + paclitaxel) improves overall survival and progression‑free survival compared with radiotherapy alone. 18 (Level II evidence)
• Cisplatin + doxorubicin also provides significant gains in progression‑free and overall survival for optimally debulked stage III‑IV disease. 18

Advanced and Recurrent Disease

• Progestational therapy (e.g., medroxyprogesterone acetate 200 mg daily) is active in steroid‑receptor‑positive grade 1‑2 tumors. 18

Management of Special Histologic Subtypes

• For serous and clear‑cell carcinoma, perform omentectomy at initial surgery. 17
• Treat all stages of these high‑risk subtypes with platinum‑based chemotherapy (carboplatin + paclitaxel) combined with radiotherapy. (Evidence implied by guideline consensus)

All statements are derived from cited evidence; citation identifiers correspond to the original references.

Management of High‑Risk Uterine Adenosquamous Carcinoma

Classification & Risk Stratification

• Adenosquamous carcinoma with high‑grade or aggressive histology should be classified with serous, clear‑cell, and carcinosarcoma as a high‑risk malignant epithelial tumor (grade 3 equivalent) according to the NCCN guidelines. 19
• These aggressive variants show a higher rate of extra‑uterine disease at presentation and failure patterns that resemble ovarian cancer. 20

Pre‑operative Evaluation

• Serum CA‑125 measurement is recommended before surgery for high‑risk endometrial tumors by the NCCN and the Society of Gynecologic Oncology (SGO). 19
• Cross‑sectional imaging with MRI or CT is advised to assess extra‑uterine spread; PET may be added to detect occult metastases. 20
• Clinical assessment should include evaluation for pelvic masses, abnormal cervical cytology, or ascites in addition to the typical presentation of postmenopausal bleeding. 19

Primary Surgical Management (Ovarian‑Cancer‑Style Staging)

• Perform total hysterectomy with bilateral salpingo‑oophorectomy. 19
• Obtain peritoneal lavage for cytology. 21
• Conduct omental biopsy or omentectomy. 21
• Take peritoneal biopsies from multiple sites. 19
• Execute pelvic and para‑aortic lymph‑node dissection. 21
• Debulk gross disease maximally when present. 20
• Fertility‑sparing surgery is contraindicated because of the high risk of distant metastasis even in apparently early disease. 19

Adjuvant Therapy

Stage IA (No Myometrial Invasion)

• Options include observation alone, systemic chemotherapy, or tumor‑directed radiation therapy, selected according to individual risk factors. 19

Stage IB or Higher (All Other Stages)

• Preferred regimen is platinum‑taxane chemotherapy (carboplatin + paclitaxel) with or without tumor‑directed radiation therapy. 19
• Platinum‑taxane regimens improve survival in serous and clear‑cell endometrial cancers and this benefit extends to other high‑risk histologies, including adenosquamous carcinoma. 20
• Combined chemotherapy (with or without radiation) is more effective than radiation alone. 19
• Routine whole‑abdominopelvic radiation is no longer recommended as primary treatment because chemotherapy‑based regimens demonstrate superior efficacy. 19

Definition of Tumor‑Directed Radiation

• Refers to external‑beam radiation and/or brachytherapy aimed at sites of known or suspected tumor involvement, typically the pelvis with optional para‑aortic fields. Whole‑abdominal radiation does not meet this definition. 19

Advanced or Metastatic Disease

First‑Line Chemotherapy Regimens

• Carboplatin + paclitaxel – most commonly used; reported response rate ≈ 40‑54 %. 19
• Cisplatin + doxorubicin + paclitaxel – modest survival advantage (≈ 15 months vs 12 months) but with significantly higher toxicity. 21

Staging System

• Use the FIGO/AJCC 7th‑edition staging system identical to that for endometrial cancers. 20
• All adenosquamous carcinomas with high‑risk features are considered grade 3 tumors regardless of architectural pattern. 20

Critical Pitfalls to Avoid

• Do not manage adenosquamous carcinoma with observation alone unless the disease is truly stage IA without myometrial invasion. 19
• Do not rely solely on sentinel‑lymph‑node mapping; given the high risk of occult metastases, complete nodal assessment is advised. 20
• Do not use whole‑abdominal radiation as primary adjuvant therapy; it is outdated and inferior to chemotherapy‑based approaches. 19

Surgical and Adjuvant Management of Early‑Stage Grade 2 Endometrioid Endometrial Cancer

Primary Surgical Procedure

• The National Comprehensive Cancer Network (NCCN) recommends total abdominal hysterectomy with bilateral salpingo‑oophorectomy as the cornerstone operation for early‑stage endometrioid carcinoma. 22
• Peritoneal washings for cytology should be obtained at the beginning of the case to aid postoperative decision‑making. 23
• A systematic inspection and palpation of the peritoneum, omentum, and visible lymph nodes is advised to detect occult extra‑uterine disease. 24
• When feasible, a minimally invasive (laparoscopic or robotic) approach is preferred over laparotomy because it provides equivalent oncologic outcomes with lower morbidity. 25

Lymph Node Assessment

• Randomized trials have shown that systematic pelvic and para‑aortic lymphadenectomy does not improve survival in early‑stage disease and therefore is not required routinely. 26
• Sentinel lymph‑node (SLN) biopsy is a reasonable option (Category 2B) for surgeons experienced in the technique, offering accurate staging with reduced morbidity. 22
• Full lymphadenectomy may be performed intraoperatively if unexpected high‑risk features are identified (e.g., deep myometrial invasion, cervical involvement, or extra‑uterine spread). 24
• The estimated risk of lymph‑node metastasis in stage IA, grade 2 tumors with < 50 % myometrial invasion is approximately 5–10 %, making routine lymphadenectomy of uncertain benefit. 26

Intraoperative Assessment

• The operating surgeon should visually and manually assess the depth of myometrial invasion to confirm it is < 50 %. 23
• The cervix must be examined for gross involvement, which would upstage the disease to stage II. 22
• Ovaries and fallopian tubes should be inspected for synchronous primary tumors. 23
• Any evidence of extra‑uterine disease (peritoneal implants, nodal enlargement) should be documented as it may alter staging and adjuvant recommendations. 26

Pathologic Evaluation Requirements

• Final pathology must record the depth of myometrial invasion (confirming < 50 %). 22
• Presence and extent of lymphovascular space invasion (LVSI) must be reported, as LVSI status drives adjuvant therapy decisions. 25
• Cervical stromal involvement should be noted, since it impacts staging. 22
• Tumor size and anatomic location are required for risk stratification. 23
• Peritoneal cytology results must be included, even though positive cytology no longer changes FIGO stage, because it may influence adjuvant treatment planning. 22
• If lymph nodes are resected, nodal status (positive vs. negative) must be documented. 23

Risk Stratification & Adjuvant Therapy (ESMO‑ESGO‑ESTRO 2016 Consensus)

• A patient with stage IA, grade 2 disease and < 50 % myometrial invasion is classified as intermediate‑risk. 26

• For patients aged ≥ 60 years, vaginal brachytherapy is strongly recommended even when other risk factors are minimal. 25

Age‑Specific Considerations

• Elderly patients (≥ 60 y) have a higher baseline risk of pelvic recurrence compared with younger women with identical pathology. 26

Avoidable Pitfalls

• Routine systematic lymphadenectomy in apparent stage IA, grade 2 disease should be avoided because it does not improve survival and adds surgical morbidity. 26
• Peritoneal washings must not be omitted; positive cytology can affect adjuvant therapy choices despite not altering FIGO stage. 22