Table 1.

Evolution of FIGO endometrial cancer staging classification over time⁴

	FIGO staging, 1961–1971	FIGO staging, 1988	FIGO staging, 2009
Basis	Clinical	Surgical-Pathologic	Surgical-Pathologic
Stage 0	Histological findings suspicious for malignancy, but not proven
Stage I	Carcinoma confined to uterine corpus *IA: Length of uterine cavity is ≤8 cm *IB: Length of uterine cavity is >8 cm	IA: Tumor limited to endometrium IB: Invasion limited to less than half of myometrium IC: invasion of half or greater of myometrium	Tumor confined to corpus uteri IA: No myometrial invasion or invasion to less than half of myometrium; endocervical glandular involvement only IB: Invasion of half or greater of myometrium
Stage II	Carcinoma involves uterine corpus and cervix	IIA: Endocervical glandular involvement only IIB: Cervical stromal invasion	Tumor invades cervical stroma but does not extend beyond uterus
Stage III	Carcinoma extends outside uterus but not outside the pelvis	IIIA: Tumor invades serosa and/or adnexa and/or positive peritoneal cytology IIIB: Vaginal metastases IIIC: Metastases to pelvis and/or para-aortic lymph nodes	Local and/or regional spread of tumor IIIA: Tumor invades serosa of corpus uteri and/or adnexa IIIB: Vaginal and/or parametrial involvement IIIC1: Positive pelvic lymph nodes IIIC2: Positive para-aortic lymph nodes
Stage IV	Carcinoma extends outside the true pelvis or obviously invades mucosa of bladder or rectum	IVA: Tumor invasion of bladder and/or bowel mucosa IVB: Distant metastases including intra-abdominal and/or inguinal lymph nodes	IVA: Tumor invasion of bladder and/or bowel mucosa IVB: Distant metastases including intra-abdominal and/or inguinal lymph nodes
Histologic grade	*Stage I tumors also subgrouped according to histologic type: G1: highly differentiated adenocarcinomas G2: differentiated adenocarcinomas with partly solid areas G3: predominately solid or entirely undifferentiated carcinomas)	Stage is irrespective of grade G1: ≤5% of non-squamous or non-morular solid growth pattern G2: 6–50% of non-squamous or non-morular solid growth pattern G3: >50% of non-squamous or non-morular solid growth pattern Notable nuclear atypia, inappropriate for architectural grade, raises the grade of a grade 1 or 2 tumor by 1	Stage is irrespective of grade G1: ≤5% of non-squamous or non-morular solid growth pattern G2: 6–50% of non-squamous or non-morular solid growth pattern G3: >50% of non-squamous or non-morular solid growth pattern Notable nuclear atypia, inappropriate for architectural grade, raises the grade of a grade 1 or 2 tumor by 1

FIGO – International Federation of Gynecology and Obstetrics

^*Modifications in 1971