A hysterectomy is required to determine the degree of myometrial invasion. The following surgical staging has been adopted by the International Federation of Gynecology and Obstetrics (FIGO) and by the American Joint Committee on Cancer:[1-3]

Stage I

Stage I endometrial cancer is carcinoma confined to the corpus uteri.

• Stage IA: tumor limited to endometrium.
• Stage IB: invasion to less than 50% of the myometrium.
• Stage IC: invasion to greater than 50% of the myometrium.

Stage II

Stage II endometrial cancer involves the corpus and the cervix but has not extended outside the uterus.

• Stage IIA: endocervical glandular involvement only.
• Stage IIB: cervical stromal invasion.

Stage III

Stage III endometrial cancer extends outside of the uterus but is confined to the true pelvis.

• Stage IIIA: tumor invades serosa and/or adnexa and/or positive peritoneal cytology.
• Stage IIIB: vaginal metastases.
• Stage IIIC: metastases to pelvic and/or para-aortic lymph nodes.

Stage IV

Stage IV endometrial cancer involves the bladder or bowel mucosa or has metastasized to distant sites.

• Stage IVA: tumor invasion of bladder and/or bowel mucosa.
• Stage IVB: distant metastases, including intra-abdominal and/or inguinal lymph nodes.

Endometrial cancer can be grouped with regard to the degree of differentiation of the adenocarcinoma, as follows:

• G1: no more than 5% of a nonsquamous or nonmorular solid growth pattern.
• G2: 6% to 50% of a nonsquamous or nonmorular solid growth pattern.
• G3: greater than 50% of a nonsquamous or nonmorular solid growth pattern.

FIGO staging for endometrial cancer:

• Stage IA G123: tumor limited to endometrium.
• Stage IB G123: invasion to less than 50% of the myometrium.
• Stage IC G123: invasion to greater than 50% of the myometrium.
• Stage IIA G123: endocervical glandular involvement only.
• Stage IIB G123: cervical stromal invasion.
• Stage IIIA G123: tumor invades serosa and/or adnexa and/or positive peritoneal cytology.
• Stage IIIB G123: vaginal metastases.
• Stage IIIC G123: metastases of pelvic and/or para-aortic lymph nodes.
• Stage IVA G123: tumor invasion of bladder and/or bowel mucosa.
• Stage IVB: distant metastases including intra-abdominal and/or inguinal lymph nodes.

References

1. Shepherd JH: Revised FIGO staging for gynaecological cancer. Br J Obstet Gynaecol 96 (8): 889-92, 1989.  [PUBMED Abstract]
   
   
2. FIGO staging for corpus cancer. Br J Obstet Gynaecol 99(5): 440, 1992. 
   
   
3. Corpus uteri. In: American Joint Committee on Cancer.: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002, pp 267-73.