Endometrial cancer is the most common cancer of the reproductive organs among American women. It can often be cured, especially when diagnosed early. About 46,000 new cases of endometrial cancer are diagnosed every year in this country. Most women with endometrial cancer are diagnosed after menopause, although some women develop the disease earlier, around the time menopause begins.
What is endometrial cancer?
The terms “endometrial cancer” and “uterine cancer” are sometimes used interchangeably, but they don’t mean exactly the same thing.
Endometrial cancer develops from a specific part of the uterus—the endometrium, which is the inner lining of the uterus. During your menstrual cycle, this lining thickens so it’s ready to support an embryo if your egg is fertilized. If the egg isn’t fertilized, the innermost layer of the endometrium is shed. This shedding is your menstrual flow. It’s regulated by the hormones estrogen and progesterone.
Most uterine cancers—more than 95 percent—start in the endometrium. These cancers are called endometrial cancers or endometrial carcinomas. (“Carcinoma” is the term for cancer that starts in one of the body’s linings.) Nearly all endometrial cancers start in the glandular cells of the endometrium. These cancers are called endometrioid adenocarcinomas.
Endometrial cancer occurs when cells in the endometrium begin to grow abnormally. They do not respond to regular cell growth, division, and death signals like they are supposed to. They also don’t organize normally. Instead they grow into a tumor, which may break through underlying layers of the uterus.
Cancer can also start in other parts of the uterus besides the endometrium, such as in the uterus’s thick outer layer of muscle (where it’s called uterine leiomyosarcoma) or in the connective tissue that supports the endometrium (where it’s called endometrial stromal sarcoma). These less common uterine sarcomas are discussed in the uterine sarcoma section.
Cancer can start in the cervix, the narrow part at the bottom of the uterus, too. This is referred to as cervical cancer, not uterine cancer.
Many women who have symptoms of endometrial cancer (vaginal bleeding after menopause or abnormal menstrual bleeding) may have a biopsy that shows precancerous changes of the endometrium, called complex hyperplasia with atypia. Risk is high that 25 to 50 percent of these women will go on to develop endometrial cancer.
To reduce the risk, doctors usually advise women with this condition to have a hysterectomy (surgery to remove the uterus) if they are past childbearing years or do not intend to become pregnant. Many gynecologists refer these women to a gynecologic oncologist for their surgery because of the chance of finding true cancer at the time of the hysterectomy.
For younger patients who hope to preserve their ability to have children, doctors may sometimes take a more conservative approach, using hormone therapy (usually progestins) to reduce cancer risk and doing close follow-up to watch for any signs of cancer.
Endometrial cancer rarely affects women before age 40. Most women with endometrial cancer are 50 years old or older.
Besides age, another important risk factor is your balance of the hormones estrogen and progesterone. Factors that shift your balance toward more estrogen can increase your risk. This is why the following are risk factors:
- Taking hormone replacement therapy (HRT) for menopause with estrogen alone. (Women who have a uterus and who take HRT can take a form that combines estrogen and progestins, which are progesterone-like drugs, to avoid increased risk for endometrial cancer. Discuss your HRT options with your doctor.)
- Having more menstrual periods—starting your period earlier in life or going through menopause later.
- Never being pregnant.
- Being overweight or obese (because body fat raises your estrogen level).
- Taking tamoxifen (Nolvadex) for breast cancer treatment
- Having breast cancer, ovarian cancer, polycystic ovary syndrome, or diabetes
- Eating a high-fat diet
- Having a sedentary lifestyle
- Having a family history of endometrial cancer
- Having Lynch syndrome
- Having had radiation therapy to your pelvic area before
- Having had endometrial hyperplasia, especially complex hyperplasia with atypia
Taking birth control pills lowers your risk for endometrial cancer.
Signs and symptoms
When endometrial cancer is diagnosed, it’s usually because a woman sees her doctor about symptoms.
The most common symptom of endometrial cancer is abnormal vaginal bleeding, such as bleeding or spotting between periods or after menopause. Some women have other abnormal vaginal discharge that doesn’t appear to have blood in it.
The following may be signs or symptoms of endometrial cancer, but they are uncommon:
- Difficult or painful urination
- Pain during intercourse
- Pain in the pelvic area
- A mass in the pelvic area
- Unexplained weight loss
Conditions other than cancer may cause these signs and symptoms. If you have any of these, see your doctor to find out the reason.
If you have signs or symptoms that could be from endometrial cancer (or another problem with your reproductive organs), your doctor will probably start by doing a general physical exam and then a pelvic exam.
To diagnose endometrial cancer, doctors have to remove a small sample of tissue from your endometrium and look at the cells under a microscope.
The most common and most accurate way to diagnose endometrial cancer is with an endometrial biopsy. The doctor inserts a thin, flexible, straw-like tube into your uterus through your cervix and scrapes or suctions out a small amount of endometrium. A pathologist examines the tissue samples. Seattle Cancer Care Alliance has a dedicated pathologist who specializes in the diagnosis of gynecologic cancers.
Less often, women need dilation and curettage (D&C). A narrow instrument called a dilator is inserted into your cervix to open it. Next the doctor uses a spoon-like tool called a curette to scrape some tissue from inside your uterus. The most common reason a woman might need a D&C instead of an endometrial biopsy is because she has cervical stenosis—the passageway through her cervix is too narrow to do a biopsy or it’s completely closed.
The only way to tell whether you have endometrial cancer is to examine samples of tissue. In certain situation, your doctor may also want you to have imaging studies to get more information, such as whether your cancer has spread. These might include an X-ray, ultrasound, computed tomography (CT) scan, and magnetic resonance imaging (MRI) scan.
Once endometrial cancer has been diagnosed, doctors perform tests to determine the stage of the cancer. Staging is the process of determining:
- The grade of your cancer (how abnormal the cells look and how likely the cancer is to grow and spread)
- Whether (and how deeply) it has invaded your uterus’s muscle layer
- Whether it has spread outside your uterus
Doctors use a cancer’s stage as a key factor in making treatment recommendations and estimating a patient’s chance for recovery. For endometrial cancer, staging is typically done at the time of surgery, which means you and your healthcare team will probably need to wait until after surgery to make some of your treatment decisions.
The most common staging system for gynecological cancers is the International Federation of Gynecology and Obstetrics (FIGO) 2010 system. This is the system that gynecologic oncologists at SCCA use.
- Stage I: Cancer is only in the body of the uterus (that is, only in the upper uterus, not in the cervix). It may have spread from the endometrium into the myometrium. There’s no cancer in the supporting connective tissue (stroma) of the cervix or outside the uterus.
- Stage II: Cancer has spread to the supporting connective tissue of the cervix but not beyond the uterus.
- Stage III: Cancer has spread outside the uterus to nearby tissue in the pelvic area—the outer surface of the uterus (serosa), the fallopian tubes, the ovaries, the vagina, the parametrium (tissue around the uterus), or regional lymph nodes (pelvic or para-aortic nodes). It has not spread outside the pelvic area.
- Stage IV: Cancer has spread to the bladder or bowel, lymph nodes in the groin (inguinal nodes), or organs outside the pelvis, such as the lungs, liver, or bones.