What is the FIGO (International Federation of Gynecology and Obstetrics) staging system and treatment for endometrial cancer?

FIGO Staging System for Endometrial Cancer

The current standard FIGO staging system for endometrial cancer is the 2009 version, which uses surgical-pathological staging based on myometrial invasion depth, cervical stromal involvement, and lymph node metastases, though a 2023 update incorporating molecular classification has been introduced but requires broader validation. 1, 2, 3

FIGO 2009 Staging System (Current Standard)

The 2009 FIGO staging system represents the widely accepted framework that transitioned from clinical to surgical staging:

Stage I: Tumor Confined to the Uterus

• Stage IA: No myometrial invasion or invasion to less than 50% of the myometrium 4, 1
• Stage IB: Invasion equal to or more than 50% of the myometrium 4, 1

Stage II: Cervical Involvement

• Stage II: Tumor invades cervical stroma but does not extend beyond the uterus 4, 1

Stage III: Local/Regional Spread

• Stage IIIA: Tumor invades the serosa of the corpus uteri and/or adnexae (ovaries/fallopian tubes) 4, 1, 5
• Stage IIIB: Vaginal and/or parametrial involvement 4, 1
• Stage IIIC1: Positive pelvic lymph nodes 4, 1
• Stage IIIC2: Positive para-aortic lymph nodes with or without pelvic nodes 4, 1

Stage IV: Advanced Disease

• Stage IVA: Tumor invasion of bladder and/or bowel mucosa 4, 1
• Stage IVB: Distant metastases including intra-abdominal and/or inguinal lymph nodes 4, 1

Surgical Staging Requirements

Complete surgical staging is essential and includes total hysterectomy with bilateral salpingo-oophorectomy as the foundation. 4, 1

The pathological assessment must document:

• Depth of myometrial invasion (ratio of invasion to total myometrial thickness) 4
• Systematic pelvic and para-aortic lymphadenectomy for intermediate-high risk disease (Stage IA G3 and IB) 4, 1
• Peritoneal washings/cytology 5
• Assessment of cervical stromal involvement 4

Critical Caveat on Lymphadenectomy

Routine systematic pelvic lymphadenectomy does not improve disease-free or overall survival in Stage I endometrial cancer based on randomized trials (Italian study and ASTEC trial), though it provides important prognostic information for tailoring adjuvant therapy. 4, 1 For intermediate-high risk disease, complete surgical staging with lymphadenectomy is recommended to guide adjuvant treatment decisions 4.

Preoperative Evaluation

The initial workup should include:

• Complete blood count, liver and renal function tests 4, 1
• Chest X-ray 4, 1
• Endometrial biopsy 4
• Contrast-enhanced dynamic MRI when cervical involvement is suspected, as this is the best tool to assess cervical invasion 4, 1, 6

Risk Stratification Based on 2009 Staging

Approximately 75% of patients present with Stage I disease, which can be subdivided into risk categories: 4, 1

• Low-risk: Stage IA, grade 1-2, endometrioid histology, no lymphovascular space invasion (LVSI) 1
• Intermediate-risk: Stage IB, grade 1-2, endometrioid histology 1
• High-risk: Stage IB grade 3, deep myometrial invasion with LVSI, or non-endometrioid histology 1

Treatment Implications by Stage

Stage I Disease

• Total hysterectomy with bilateral salpingo-oophorectomy is the standard surgical approach 4
• Laparoscopic approach provides equivalent disease-free survival and overall survival compared to laparotomy, with shorter hospital stay, less pain, and improved quality of life 4

Stage II Disease

• Radical hysterectomy with bilateral salpingo-oophorectomy and systematic pelvic lymphadenectomy with or without para-aortic lymphadenectomy 4
• Lymphadenectomy is essential to guide surgical staging and adjuvant therapy 4

Stage IIIA Disease with Ovarian Involvement

• Maximal surgical cytoreduction for patients with good performance status 5
• Adjuvant chemotherapy with platinum-based regimens (carboplatin/paclitaxel or cisplatin/doxorubicin) is standard, as it significantly improves progression-free and overall survival compared to radiation alone 5
• Pelvic radiotherapy may be added for locoregional control 5

FIGO 2023 Update: Important Context

A new FIGO staging system was introduced in 2023 that incorporates histological subtypes, lymphovascular space invasion patterns, and molecular classification (POLEmut, MMRd, NSMP, p53abn). 2, 3 This represents a significant departure from traditional anatomical staging systems. 7, 2, 3

However, this 2023 system requires multi-institutional validation and broader adoption before replacing the 2009 system in routine practice. 7 The 2009 staging remains the current standard for clinical use, as existing literature and treatment algorithms are based on this framework. 4, 1

Key Clinical Pitfalls to Avoid

• Do not rely on clinical staging alone—endometrial cancer requires surgical-pathological staging 4, 8
• Do not perform routine systematic lymphadenectomy in low-risk Stage I disease, as randomized trials show no survival benefit 4, 1
• Do not omit MRI when cervical involvement is suspected, as this significantly impacts surgical planning 4, 1
• Recognize that positive peritoneal cytology alone was removed from staging criteria in the 2009 revision 4