Your uterus is the organ where a fetus develops. It’s a pear-shaped organ located behind your bladder and in front of the sigmoid colon. It’s connected to your ovaries by the fallopian tubes. The bottom part, the cervix, connects your uterus to your vagina.
When cells change and begin to grow abnormally in your uterus, it’s called uterine or endometrial cancer.
Uterine cancer is the most common gynecologic cancer in the US. The American Cancer Society estimates that more than 65,000 women are diagnosed each year. Because most uterine cancer is detected early, most women survive the disease.
There are two main types of uterine cancer.
Most uterine cancer starts in the inner lining of your uterus, called the endometrium. Endometrioid adenocarcinomas are the most common subtype. Uterine papillary serous carcinomas and clear cell sarcomas are less common and more aggressive than endometrioid carcinomas.
About 5% of uterine cancer starts in the muscle wall of your uterus. These are called uterine sarcomas. Common types of uterine sarcomas are leiomyosarcoma, adenosarcoma, endometrial stromal sarcoma, and undifferentiated sarcomas. Their behavior and treatment can differ from each other, based on their usual pattern of spread and risk of recurrence.
The most common form of uterine cancer is called endometrioid cancer. It can start when the hormone estrogen triggers cells in the inner lining (endometrium) to grow abnormally. Risk factors for uterine cancer are related to estrogen or to an inherited genetic disorder called Lynch syndrome.
Risks for uterine cancer include:
Fat cells produce estrogen that can stimulate the endometrium. In the US, more than twice the number of overweight women are diagnosed with uterine cancer than normal weight women.
Unopposed estrogen, sometimes given to postmenopausal women, increases the risk of uterine cancer. Giving this therapy with the hormone progesterone lowers risk substantially.
Early Menstruation, Late Menopause, Never Having Been Pregnant
Starting your period before you’re 12, entering menopause after age 55, or not having pregnancies increases your odds of getting uterine cancer.
Using Tamoxifen, a breast cancer treatment and prevention drug, can slightly increase your risk of getting uterine cancer. But the prevention benefit usually outweighs the risks.
Endometrial hyperplasia is a precancerous condition of the endometrium. There are several types of endometrial hyperplasia. Complex atypical endometrial hyperplasia has the highest risk of cancer. It’s usually treated with surgery or with the hormone progesterone.
This inherited genetic syndrome increases your risk of uterine and colon cancer, among others.
The most common sign of uterine cancer is abnormal vaginal bleeding—ranging from a watery and blood-streaked flow to vaginal discharge that contains more blood. For premenopausal women this could be heavy periods and prolonged bleeding. Any kind of bleeding during or after menopause is often a sign of a problem.
Other symptoms can be abnormal Pap test results and pelvic pain.
Most uterine cancer is detected early when it’s very likely to be cured. It’s usually diagnosed with a uterine biopsy. In this test, your doctor will take a small tissue sample from the inside of your uterus. Your doctor can often do this test in their office with little discomfort to you.
In some scenarios in which office biopsy isn’t possible or is not sufficient, you might have an outpatient procedure called a dilation and curettage (D&C) with or without hysteroscopy. This procedure happens in an operating room with you under sedation or anesthesia. Your doctor will use a small tool to dilate (open) your cervix—the lower part of your uterus. Then they’ll use a metal curette tool to sample the endometrial tissue. They may also take a look inside your uterus with a small camera, called hysteroscopy.
Your doctor will send tissue samples to a pathologist, who will look for abnormalities.
If tests indicate you have uterine cancer, they will refer you to a gynecologic oncologist. This doctor is specially trained in gynecologic cancers.
Your gynecologic oncologist may recommend tests that show how far the tumor has grown and spread into your body.
- A CT (computed tomography) scan of your abdomen and pelvis, which converts data from different angles of X-ray images of your body into pictures on a monitor.
- An MRI (magnetic resonance imaging) test, which uses powerful magnetic fields to create a 3D picture of your lower abdomen and pelvis to detect tumors.
- A pelvic ultrasound, which uses sound waves to form images of the body.
Cancer stages indicate whether cancer is confined to its site of origin or has spread into nearby tissues or further into your body. Your cancer’s stage, among other things, will determine your course of treatment.
- IA. Tumor confined to the uterus with less than 50% myometrial invasion
- IB. Tumor confined to the uterus with greater than 50% myometrial invasion
- II. Cervical stromal invasion, but not beyond uterus
- IIIA. Tumor invades serosa or adnexa
- IIIB. Vaginal and/or parametrial involvement
- IIIC1. Pelvic lymph node involvement
- IIIC2. Para-aortic lymph node involvement
- IVA. Tumor invasion of bladder and/or bowel mucosa
- IVB. Distant metastases, including abdominal metastases and/or inguinal lymph node