Endometrial cancer develops when cells in the endometrium begin to grow out of control and can then invade nearby tissues or spread throughout the body. Large collections of this out of control tissue are called tumors. However, some tumors are not really cancer because they cannot spread or threaten someone's life. These are called benign tumors. The tumors that can spread throughout the body or invade nearby tissues are considered cancer and are called malignant tumors. The distinction between benign and malignant tumors is very important in uterine cancer because there are many benign processes affecting the uterus that may get confused with cancers. Fibroids are very common, benign tumors of the uterus that are not cancerous. They can occasionally cause increased vaginal bleeding, vaginal discharge, or pain. Your doctor may suggest that you have fibroids removed if they are becoming bothersome.
Cancers are characterized by the normal cells from which they form. The most common type of endometrial cancer is called endometrioid adenocarcinoma; it comes from cells that form glands in the endometrium and it has a characteristic appearance under the microscope. Endometrioid endometrial cancer compromises about 75-80% of all endometrial cancers. The second most common form is papillary serous adenocarcinoma (about 10% of all endometrial cancers) and another form is clear cell adenocarcinoma (about 4-5% of all endometrial carcinomas). Both papillary serous and clear cell adenocarcinomas tend to be more aggressive than endometrioid adenocarcinomas, and are often detected at advanced stages. Sometimes an endometrial cancer has features of more than one subtype; this is called a mixed adenocarcinoma and they make up about 10% of all endometrial cancers. There are a few other rare types like mucinous adenocarcinoma and squamous cell adenocarcinoma that each compromise less than 1% of endometrial cancers.
How is endometrial cancer diagnosed and staged?
When a post-menopausal woman has new onset vaginal bleeding, or any woman has symptoms that suggest a possibility of endometrial cancer, their doctors will want to get a sample of their endometrium called an endometrial biopsy. A biopsy is the only way to know for sure if you have cancer, because it allows your doctors to get cells that can be examined under a microscope. Once the tissue is removed, a doctor known as a pathologist will review the specimen. The pathologist can tell if it is cancer or not; and if it is cancerous, then the pathologist will characterize it by what type of tissue it arose from and what subtype of cancer it is, how abnormal it looks (known as the grade), and whether or not it is invading surrounding tissues.
The least invasive method to get a biopsy is to do it in your doctor's office. A thin flexible tube is passed through a woman's vagina and cervix and then into her uterus. A small amount of endometrium is removed; this can be somewhat uncomfortable and sometimes anti-inflammatory medications can help with the pain. Occasionally, your doctor will not be able to get enough endometrial tissue with an office biopsy. In this case, you will need to have a dilation and curettage (D & C). D&Cs are done in the hospital, in the operating room under anesthesia. Your doctor dilates the opening to your uterus and then scrapes and samples some endometrial tissue. This is often done with the aide of a thin scope, so your doctors can see what the inside of your uterus looks like.
Another technique that can help make the diagnosis of endometrial cancer is called transvaginal ultrasound. Ultrasound is an imaging modality that uses sound waves that bounce off of tissues and provide a picture of whatever is being investigated. By inserting an ultrasound probe into a woman's vagina, doctors can get a pretty good look at the thickness of her endometrium. If it appears too thick, then biopsies can be taken.
Endometrial cancer is a type of cancer that needs to be staged during a surgery; it is usually staged and treated during the same operation. In order to guide treatment and offer some insight into prognosis, endometrial cancer is staged into four different groups at the time of the surgery. Surgeons who specialize in gynecologic malignancies go through a careful inspection and sampling of a woman's pelvis during this procedure, and biopsy specimens are sent to a pathologist while the surgeon is still working. The staging system used for endometrial cancer is the FIGO system (International Federation of Gynecologists and Obstetricians). The staging system is somewhat complex, but here is a simplified version of it:
Endometrial cancer confined to the body of the uterus (no cervical spread).
Endometrial cancer which has spread to the cervix (but not outside the uterus).
Endometrial cancer outside the uterus, but confined to the pelvis (but not in the bladder or rectum), cancer may have spread to pelvic lymph nodes.
Endometrial cancer which has spread to the bladder or rectum, or has distant metastasis (spread) to other organs.
Generally, the higher the stage, the more serious the cancer is. Although surgery is required for staging, your physicians may want to order some other tests to better characterize the mass/masses and look for distant spread. Tests like CT scans (a 3-D x-ray) or MRIs (like a CT scan but done with magnets) can examine the pelvis and localized lymph nodes. You may also get a colonoscopy, which uses a lighted scope to examine your rectum and colon, or a barium enema in which dye is inserted into your rectum and an x-ray is taken. These tests are to look for spread of the tumor to your colon and rectum. Your doctor may order a blood test called a CA-125, which if positive, predicts that there is spread of the cancer outside of your uterus. Each patient is an individual so the specific tests people get will vary; but overall, your doctors want to know as much about your particular tumor as possible so that they can plan the best available treatments.