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Cancer InDepth: Uterine (Endometrial) Cancer

Uterine cancer is a disease in which cancer cells grow in the uterus (womb).

The uterus is a pear-shaped organ vital to child bearing. During a woman’s fertile years, the uterus prepares each month to receive and nourish a fertilized egg. Hormonal changes direct the uterine lining to thicken. If no fertilized egg arrives, the uterus sheds the additional cells during menstruation. If the egg is fertilized, the developing fetus grows inside the uterus.

Cancer occurs when cells in the body (in this case uterus cells) divide without control or order. Normally, cells divide in a regulated manner. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms. This is called a growth or tumor. The term cancer refers to malignant tumors, which can invade nearby tissues and spread to other parts of the body. A benign tumor does not invade or spread.

The walls of the uterus are made up of the endometrium, the inner lining, and the myometrium, the muscular, outer lining. The most common type of cancer of the uterus begins in the endometrium. There are different types of endometrial cancers. All of these tumors involve the glandular cells. The most common type is endometrioid adenocarcinomas. The other types, papillary serous adenocarcinomas and clear cell adenocarcinomas, grow and spread more rapidly than endometrioid adenocarcinomas.

Uterine Cancer
Uterine Cancer
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Ninety-fine percent of uterine cancers are endometrial cancers. Other, more rare types of uterine cancers include:

  • Stromal sarcomas, which develop in the stroma or connective tissue
  • Carcinosarcomas or malignant mixed mesodermal tumors, which combine characteristics of endometrial cancer and sarcomas
  • Leiomyosarcomas, which begin in the myometrium (muscle wall of the uterus)

The information provided here will focus solely on endometrial cancer. Treatment and prognosis for these rare forms of cancer differ from endometrial cancer.

Who Is Affected

Endometrial cancer is the most common female reproductive-tract cancer. The American Cancer Society estimates 39,300 women will learn they have the disease this year, and 7,400 will die from it. Lifetime risk of developing the disease is 2.45%. Endometrial cancer rarely occurs in women younger than 40. The risk of developing it increases with age.

Causes and Complications

The exact cause of uterine cancer is unknown. Exposure to the hormone estrogen without the counter-balancing effect of the progesterone hormone seems to be strongly related to the development of this cancer.

Excessive bleeding, or hemorrhage, is a complication of uterine cancer. The most common first sign of uterine cancer is passing blood from the vagina in a woman who has already gone through menopause.

Revision Information

  • Abeloff M. Clinical Oncology. 2nd ed. Orlando, FL: Churchill Livingstone, Inc; 2000: 1987-2008.

  • American Cancer Society website. Available at: http://www.cancer.org/ .

  • Bast R, Kufe D, Pollock R, et al, eds. Cancer Medicine. 5th ed. Hamilton, Ontario: BC Decker Inc; 2000.

  • National Cancer Institute website. Available at: http://www.nci.nih.gov/ .

  • Rakel R. Bope E, ed. Conn's Current Therapy. 54th ed. St. Louis, MO: WB Saunders; 2002: 1094-1096.