UTERUS ENDOMETRIUM (ICD‐O‐3 C54.0, 1, 3, 8, 9, C55)

The definitions of the T, N, and M categories correspond to the FIGO stages. Both systems are included for comparison.

Rules for Classification

The classification applies to endometrial carcinomas and carcinosarcomas (malignant mixed mesodermal tumours). There should be histological verification with subdivision by histological type and grading of the carcinomas. The diagnosis should be based on examination of specimens taken by endometrial biopsy.

The FIGO stages are based on surgical staging. TNM stages are based on clinical and/or pathological classification.

Anatomical Subsites (Fig. 424)

Isthmus uteri (C54.0)
Fundus uteri (C54.3)
Endometrium (C54.1)

Regional Lymph Nodes (Fig. 425)

The regional lymph nodes are the pelvic (hypogastric [obturator, internal iliac] (3), common (5) and external (4) iliac, parametrial (2), and sacral (6)) and the para‐aortic nodes (7).

TNM Clinical Classification

T – Primary Tumour

TNM Categories	FIGO Stages	Definition
TX		Primary tumour cannot be assessed
T0		No evidence of primary tumour
T1	I*	Tumour confined to the corpus uteri¹ (Fig. 437)
T1a	IA*	Tumour limited to the endometrium or invading less than half of myometrium
T1b	IB	Tumour invades one half or more of myometrium
T2	II	Tumour invades cervical stroma, but does not extend beyond the uterus² (Fig. 438)
T3	III	Local and/or regional spread as specified below
T3a	IIIA	Tumour invades the serosa of the corpus uteri or adnexae (direct extension or metastasis) (Fig. 439)
T3b	IIIB	Vaginal or parametrial involvement (direct extension or metastasis) (Fig. 439)
N1	IIIC	Metastasis to pelvic or para‐aortic lymph nodes (Fig. 441)
	IIIC1	Metastasis to pelvic lymph nodes
	IIIC2	Metastasis to para‐aortic lymph nodes with or without metastasis to pelvic lymph nodes
T4M1	IVAIVB	Tumour invades bladder/bowel mucosa³ (Fig. 440)Distant metastasis

Notes
¹Endocervical glandular involvement only should now be considered as stage I.

²Positive cytology has to be reported separately without changing the stage.

³The presence of bullous oedema is not sufficient evidence to classify as T4.

Schematic illustration of tumour confined to the corpus uteri. — **Fig. 437**

Schematic illustration of tumour invades cervical stroma, but does not extend
beyond the uterus. — **Fig. 438**

Schematic illustration of Vaginal or parametrial involvement. — **Fig. 439**

Schematic illustration of Metastasis to pelvic or para-aortic lymph nodes. — **Fig. 440**

Schematic illustration of tumour invades bladder or bowel mucosa. — **Fig. 441**

N – Regional Lymph Nodes

NX	Regional lymph nodes cannot be assessed
N0	No regional lymph node metastasis
N1	Pelvic lymph node metastasis
N2	Para‐aortic lymph node metastasis

M – Distant Metastasis

M0	No distant metastasis
M1	Distant metastasis (excluding metastasis to vagina, pelvic serosa, or adnexa, including metastasis to inguinal lymph nodes, intra‐abdominal lymph nodes other than para‐aortic or pelvic nodes)

pTNM Pathological Classification

The pT and pN categories correspond to the T and N categories.

pM1	Distant metastasis microscopically confirmed

Note
pM0 and pMX are not valid categories.

pN0

Histological examination of a pelvic lymphadenectomy specimen will ordinarily include 6 or more lymph nodes. If the lymph nodes are negative, but the number ordinarily examined is not met, classify as pN0.