Uterine Cancer, Endometrial
This page has important information about cancer* of the uterus. In the United States, cancer of the uterus is the most common cancer of the female reproductive system. It accounts for six percent of all cancers in women in this country.
This booklet has information about the possible causes, symptoms, diagnosis, and treatment of cancer of the uterus. It will help patients and their families and friends better understand and cope with this disease.
Research is increasing what we know about cancer of the uterus. Scientists are learning more about its causes. They are exploring new ways to prevent, detect, diagnose, and treat this disease. Research has helped to improve patients' quality of life and lower the chance of dying from this disease.
The uterus is part of a woman's reproductive system. It is the hollow, pear-shaped organ where a baby grows. The uterus is in the pelvis between the bladder and the rectum.
The narrow, lower portion of the uterus is the cervix. The broad, middle part of the uterus is the body, or corpus. The dome-shaped top of the uterus is the fundus. The fallopian tubes extend from either side of the top of the uterus to the ovaries.
The uterus and other reproductive organs.
The wall of the uterus has two layers of tissue. The inner layer, or lining, is the endometrium. The outer layer is muscle tissue called the myometrium.
In women of childbearing age, the lining of the uterus grows and thickens each month to prepare for pregnancy. If a woman does not become pregnant, the thick, bloody lining flows out of the body through the vagina. This flow is called menstruation.
Cancer is a group of many related diseases. All cancers begin in cells, the body's basic unit of life. Cells make up tissues, and tissues make up the organs of the body.
Normally, cells grow and divide to form new cells as the body needs them. When cells grow old and die, new cells take their place.
Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.
Tumors can be benign or malignant:
- Benign tumors are not cancer. Usually, doctors can remove them. Cells from benign tumors do not spread to other parts of the body. In most cases, benign tumors do not come back after they are removed. Most important, benign tumors are rarely a threat to life.
Benign Conditions of the Uterus
- Fibroids are common benign tumors that grow in the muscle of the uterus. They occur mainly in women in their forties. Women may have many fibroids at the same time. Fibroids do not develop into cancer. As a woman reaches menopause, fibroids are likely to become smaller, and sometimes they disappear.
- Endometriosis is another benign condition that affects the uterus. It is most common in women in their thirties and forties, especially in women who have never been pregnant. It occurs when endometrial tissue begins to grow on the outside of the uterus and on nearby organs. This condition may cause painful menstrual periods, abnormal vaginal bleeding, and sometimes loss of fertility (ability to get pregnant), but it does not cause cancer. Women with endometriosis may be treated with hormones or surgery.
- Endometrial hyperplasia is an increase in the number of cells in the lining of the uterus. It is not cancer. Sometimes it develops into cancer. Heavy menstrual periods, bleeding between periods, and bleeding after menopause are common symptoms of hyperplasia. It is most common after age 40.
Usually, fibroids cause no symptoms and need no treatment. But depending on their size and location, fibroids can cause bleeding, vaginal discharge, and frequent urination.
Women with these symptoms should see a doctor. If fibroids cause heavy bleeding, or if they press against nearby organs and cause pain, the doctor may suggest surgery or other treatment.
To prevent endometrial hyperplasia from developing into cancer, the doctor may recommend surgery to remove the uterus (hysterectomy) or treatment with hormones (progesterone) and regular followup exams.
- Malignant tumors are cancer. They are generally more serious and may be life threatening. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or lymphatic system. That is how cancer cells spread from the original (primary) tumor to form new tumors in other organs. The spread of cancer is called metastasis.
When uterine cancer spreads (metastasizes) outside the uterus, cancer cells are often found in nearby lymph nodes, nerves, or blood vessels. If the cancer has reached the lymph nodes, cancer cells may have spread to other lymph nodes and other organs, such as the lungs, liver, and bones.
When cancer spreads from its original place to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if cancer of the uterus spreads to the lungs, the cancer cells in the lungs are actually uterine cancer cells. The disease is metastatic uterine cancer, not lung cancer. It is treated as uterine cancer, not lung cancer. Doctors sometimes call the new tumor "distant" disease.
The most common type of cancer of the uterus begins in the lining (endometrium). It is called endometrial cancer, uterine cancer, or cancer of the uterus. In this booklet, we will use the terms uterine cancer or cancer of the uterus to refer to cancer that begins in the endometrium.
A different type of cancer, uterine sarcoma, develops in the muscle (myometrium). Cancer that begins in the cervix is also a different type of cancer. This booklet does not deal with uterine sarcoma or with cancer of the cervix. ,/
Uterine Cancer: Who's at Risk?
No one knows the exact causes of uterine cancer. However, it is clear that this disease is not contagious. No one can "catch" cancer from another person.
Women who get this disease are more likely than other women to have certain risk factors. A risk factor is something that increases a person's chance of developing the disease.
Most women who have known risk factors do not get uterine cancer. On the other hand, many who do get this disease have none of these factors. Doctors can seldom explain why one woman gets uterine cancer and another does not.
Studies have found the following risk factors:
- Age.Cancer of the uterus occurs mostly in women over age 50.
- Endometrial hyperplasia. The risk of uterine cancer is higher if a woman has endometrial hyperplasia. This condition and its treatment are described above.
- Hormone replacement therapy (HRT). HRT is used to control the symptoms of menopause, to prevent osteoporosis (thinning of the bones), and to reduce the risk of heart disease or stroke.
Women who use estrogen without progesterone have an increased risk of uterine cancer. Long-term use and large doses of estrogen seem to increase this risk. Women who use a combination of estrogen and progesterone have a lower risk of uterine cancer than women who use estrogen alone. The progesterone protects the uterus.
Women should discuss the benefits and risks of HRT with their doctor. Also, having regular checkups while taking HRT may improve the chance that the doctor will find uterine cancer at an early stage, if it does develop.
- Obesity and related conditions. The body makes some of its estrogen in fatty tissue. That's why obese women are more likely than thin women to have higher levels of estrogen in their bodies. High levels of estrogen may be the reason that obese women have an increased risk of developing uterine cancer. The risk of this disease is also higher in women with diabetes or high blood pressure (conditions that occur in many obese women).
- Tamoxifen. Women taking the drug tamoxifen to prevent or treat breast cancer have an increased risk of uterine cancer. This risk appears to be related to the estrogen-like effect of this drug on the uterus. Doctors monitor women taking tamoxifen for possible signs or symptoms of uterine cancer.
The benefits of tamoxifen to treat breast cancer outweigh the risk of developing other cancers. Still, each woman is different. Any woman considering taking tamoxifen should discuss with the doctor her personal and family medical history and her concerns.
- Race. White women are more likely than African-American women to get uterine cancer.
- Colorectal cancer. Women who have had an inherited form of colorectal cancer have a higher risk of developing uterine cancer than other women.
Other risk factors are related to how long a woman's body is exposed to estrogen. Women who have no children, begin menstruation at a very young age, or enter menopause late in life are exposed to estrogen longer and have a higher risk.
Women with known risk factors and those who are concerned about uterine cancer should ask their doctor about the symptoms to watch for and how often to have checkups. The doctor's advice will be based on the woman's age, medical history, and other factors.
Uterine cancer usually occurs after menopause. But it may also occur around the time that menopause begins. Abnormal vaginal bleeding is the most common symptom of uterine cancer. Bleeding may start as a watery, blood-streaked flow that gradually contains more blood. Women should not assume that abnormal vaginal bleeding is part of menopause.
A woman should see her doctor if she has any of the following symptoms:
- Unusual vaginal bleeding or discharge
- Difficult or painful urination
- Pain during intercourse
- Pain in the pelvic area
These symptoms can be caused by cancer or other less serious conditions. Most often they are not cancer, but only a doctor can tell for sure.