Endometrial Cancer

This article discusses the impact of endometrial cancer on women’s health with an emphasis on screening and early detection.  Unfortunately, there is not a long list of symptoms or warning signs for endometrial cancer.  This is why this article focuses more on the normal function, evaluation and treatment options for endometrial cancer.  Endometrial cancer is another term for cancer of the lining of the uterus or simply uterine cancer.  This is a common cancer as is seen below.

The top 10 most common cancers diagnosed in women in the United States from 2003-2007.

Why exactly is the endometrium?

By understanding the anatomy and function of it, disease symptoms and abnormalities will be better understood.  The uterus is a pear shaped organ in women that is found in the pelvis and connects to the vagina via the cervix.  The uterus is a hollow muscle that has the main function of providing a safe and hospitable area for a newly fertilized egg to implant and grow into a fetus and eventually be born.  The uterus is between the bladder (in front of it) and the rectum (behind it).  The uterus is pear shaped but more like an upside-down pear.  The narrow area of the pear is the isthmus that connects to the cervix and vagina.  The “top” of the pear has two wing-like arms that are called fallopian tubes.

These tubes allow passage of an egg from the nearby ovary.  The uterus in most women is a small organ and about 3-5 inches long and 2-4 inches wide.  The average uterus in an adult woman weighs about 50 grams.  After pregnancy the resting state of the uterus can be about 50% to 100% bigger.  During pregnancy the uterus expands greatly up to 25x its original dimensions.  As a woman ages and is no longer fertile (i.e. post-menopausal) the uterus shrinks without production of the usual hormones from the ovary.

The uterus has layers like most other structures in the body.  The innermost layer is called the endometrium.  The middle layer is composed of thick layers of muscle.  This muscle has a generous blood supply with many veins and artery branches.  The outer layer of the uterus has a lining similar to the colon or bladder.  The blood supply to the uterus is a branch of the main artery that supplies the pelvis – the internal iliac artery.  This artery runs very close to the ureter which is the drainage tube from the kidney to the bladder.  This is important for the treating physician to know because often treatments of cancer of the uterus place the ureter at risk for injury.  An injury to the ureter can have devastating consequences.

The hormones that regulate the menstrual cycle (i.e. estrogen and progesterone) also affect the growth and shedding of the endometrium.  Early in the cycle the endometrium grows taller in the proliferative phase.  The average menstrual cycle is about 28 days.  Midway at day 14 is when ovulation occurs.  After this the endometrial lining begins to secrete and become thicker.  This is known as the secretory phase.  If the ovulated egg does not join with a sperm and implant into the thick endometrium then the lining will disrupt at about 28 days.  This disruption or shedding of lining is known as menses or the process of menstruation that occurs monthly for women.  The lining of the uterus, the endometrium, has receptors that respond to stimulation from hormones such as estrogen.  An abnormal growth of the endometrium is most likely to cause bleeding that will simulate a menstruation in an abnormal way.  If there is bleeding apart from a normal period or after the menstrual cycle has ceased this is considered abnormal and a potential symptom of endometrial cancer.  If a woman has had irregular, scarce or no periods for some length of time and then begins to have them heavier or irregularly then this could be a sign of endometrial cancer.

The endometrial lining normally grows in a cyclical way.  In the same manner, the endometrium can grow in an abnormal way without being a true cancer.  As the lining of the endometrium becomes taller and the cells become more dense (also known as endometrial hyperplasia) the potential for cancer to arise in this type of environment increases.  This will also manifest as irregular or post-menopausal bleeding.

The most common scenario that leads to discovery of endometrial cancer is an older woman who has stopped regular periods who begins to get one again.  The most important and common symptom of endometrial cancer is POST-MENOPAUSAL UTERINE BLEEDING.  This refers to bloody discharge form the vagina in an older woman.  It is important to realize that not all irregular bleeding or bleeding that occurs in an older woman is from an endometrial cancer.

Other causes of bleeding that are not cancer include:

  • Infection of the uterus or cervix
  • Wasting of the uterus or lining
  • Injury
  • A foreign body such as a IUD (intra-uterine device)
  • Benign muscle tumor (i.e. uterine fibroid)
  • Medication such as hormone replacement therapy, blood thinners (e.g. warfarin).
  • Bleeding disorders

There are several ways to assess the health and function of the uterus.  A normal menstrual cycle or absence of bleeding in the post-menopausal woman is sign of a healthy uterus.  During a physical examination, a physician can check the position and fullness of the uterus to feel for any abnormalities.  Another way to check the health of the uterus is with an ultrasound to measure the thickness of the lining.   An ultrasound can measure the size of the uterus and the thickness of the endometrium as well as look for irregularities in the “landscape” of the endometrium.

A normal endometrium is only a few millimeters and should not have much irregularity.  If an older woman with new onset bleeding is examined and also has an ultrasound that shows a tall or irregular endometrium, than this is very concerning for endometrial cancer.  Another way to assess the health of the uterus and its inner lining the endometrium is to take a sample of it with a needle or similar device.  Taking a sample of cells from an area of the body is also called a biopsy.  A biopsy of the endometrium allows examination of a small part of the uterine lining to look for irregularities or for cancer.  If cancer is seen, the type of cancer can also be determined.  Further treatment involves checking to see if there is any disease outside of the uterus and usually results in surgery to remove the uterus (also known as hysterectomy).

REFERENCES: 

  1. www.cancer.gov/cancertopics/types/endometrial
  2. www.nlm.nih.gov/medlineplus/ency/article/000910.htm
  3. Katz, VL; Lentz GM; Lobo RA; Gershenson DM. (2007) Katz: Comprehensive Gynecology, 5th ed. Chapters 3, 32. Philadelphia, PA: Mosby Elsevier
  4. Townsend Jr, CM; Beauchamp RD; Evers BM; Mattox KL. (2008) Townsend: Sabiston Textbook of Surgery, 18th ed.  Chapter 75.  New York, NY: Saunders.
  5. This article was originally published on September 3, 2012 and last revision and update was 9/4/2015.