Criteria

FIGO staging of uterine cancer (2023)[152]

The FIGO staging system for endometrial cancer was updated in 2023 to include advances in pathological and molecular knowledge. New sub-classifications have been added based on histopathological findings, with additional classification included for molecular findings after surgical staging for early endometrial cancer.

Stage I: Non-aggressive histological type without invasion of cervical stroma or substantial LVSI, or aggressive type limited to the endometrium

  • IA1: Non-aggressive limited to a polyp or confined to the endometrium

  • IA2: Non-aggressive involving less than 50% of the myometrium with no or focal lymphovascular space invasion (LVSI)

  • IA3: Low-grade endometrioid carcinomas limited to the uterus with simultaneous low-grade endometrioid ovarian involvement

  • IB: Non-aggressive involving 50% or more of the myometrium with no LVSI or focal LVSI

  • IC: Aggressive, that is, serous, high-grade endometrioid, clear cell, carcinosarcomas, undifferentiated, mixed, and other unusual types without any myometrial invasion

Stage II: Non-aggressive histological type with invasion of cervical stroma or substantial LVSI, or aggressive type with myometrial invasion

  • IIA: Non-aggressive that infiltrates the cervical stroma

  • IIB: Non-aggressive with substantial LVSI

  • IIC: Aggressive with any myometrial invasion

Stage III: Local and/or regional spread of tumour (any histological type)

  • IIIA: Invasion of uterine serosa, adnexa, or both by direct extension or metastasis (IIIA1 ovary or fallopian tube; IIIA2 uterine subserosa or serosa infiltration)

  • IIIB: Metastasis or direct spread to the vagina and/or parametria or pelvic peritoneum (IIIB1 infiltration of vagina/parametria; IIIB2 pelvic peritoneal metastasis)

  • IIIC: Metastasis to the pelvic and/or para-aortic lymph nodes (IIIC1 pelvic lymph node involvement [IIIC1i micrometastasis, IIIC1ii macrometastasis]; IIIC2 metastasis to para-aortic lymph nodes up to the renal vessels, with or without pelvic lymph node involvement [IIIC2i micrometastasis, IIIC2ii macrometastasis]

Stage IV: Tumour invades the bladder and/or bowel mucosa, and/or distant metastases

  • IVA: Locally advanced disease infiltrating the bladder or rectal mucosa

  • IVB: Extrapelvic peritoneal metastasis

  • IVC: Distant metastasis

Molecular classification:

  • IAm(POLEmut): POLE mutation, endometrial cancer confined to uterine corpus or with cervical extension, regardless of LVSI (any histological type)

  • IICm(p53abn): p53 abnormal, endometrial cancer confined to uterine corpus with any myometrial invasion, with or without cervical invasion, regardless of LVSI (any histological type).

Stages III and IV are not modified by molecular classification; however, molecular classification should be recorded for all tumours where known.

International Federation of Gynecology and Obstetrics (FIGO) staging of uterine cancer (2009)[8]

Stage I: tumour limited to the corpus uteri

  • IA: no or <50% myometrial invasion

  • IB: ≥50% myometrial invasion.

Stage II: tumour invades cervical stroma, but does not extend beyond the uterus

  • Endocervical glandular involvement only should be considered as stage I and no longer as stage II.

Stage III: local and regional spread of the tumour

  • IIIA: tumour invades the serosa of the corpus uteri and/or adnexa; positive cytology has to be reported separately without changing the stage

  • IIIB: vaginal and/or parametrial involvement

  • IIIC: metastases to pelvic and/or para-aortic lymph nodes

  • IIIC1: positive pelvic nodes

  • IIIC2: positive para-aortic lymph nodes with or without positive pelvic lymph nodes.

Stage IV: tumour invades the bladder and/or bowel mucosa and/or distant metastases

  • IVA: tumour invasion of the bladder and/or bowel mucosa

  • IVB: distant metastases including intra-abdominal metastases and/or inguinal lymph nodes.

Simplified FIGO staging[153]

The FIGO staging classification is sometimes simplified to:

  • Organ confined

  • Non-organ confined.

Non-organ confined is most commonly divided into:

  • Node-positive

  • Metastatic.

Alternatively, it may be divided into:

  • Early

  • Advanced (locally advanced, inoperable, or recurrent).

Risk stratification criteria

Following clinical evaluation, staging surgery, and histopathology assessment, women with endometrial cancer can be stratified based on risk of recurrence to help guide treatment planning.

Low risk:

  • Stage IA endometrioid carcinoma without myometrial invasion

Intermediate risk:

  • Stage IA endometrioid carcinoma with myometrial invasion

  • Stage IB or II endometrioid carcinoma

High risk:

  • Stages III to IV endometrioid carcinoma

  • Non-endometrioid (type 2) carcinomas (e.g., serous, clear-cell, undifferentiated carcinoma, carcinosarcoma)

Intermediate-risk patients can be further stratified as low- or high-intermediate risk according to age and presence of the following risk factors (based on the GOG-99 study criteria): tumour grade 2 or 3; lymphovascular space invasion; and outer third myometrial invasion:[154]

Low-intermediate risk:

  • Age <50 years and ≤2 risk factors

  • Age 50-69 years and ≤1 risk factor

  • Age ≥70 years and no risk factors

High-intermediate risk:

  • Any age and 3 risk factors

  • Age 50-69 years and ≥2 risk factors

  • Age ≥70 years and ≥1 risk factor.

Stage IB or II disease that is deeply invasive, with gross cervical involvement, and/or grade 3 is often considered high risk.

Other risk stratification criteria for endometrial cancer have been proposed, such as the PORTEC study criteria, but the GOG-99 criteria are commonly used in the US.​​[155]​​​​​​

Molecular studies are encouraged to complement surgical staging.[83]​ Molecular classification (POLE-mutated, MMR-deficient, p53-abnormal, and no specific molecular profile) can be incorporated into conventional histopathological classification and risk stratification.[3][116][123]​​[152]​​

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