What Stage III Endometrial Cancer Really Means
When endometrial cancer reaches stage III, the cancer has spread outside the uterus but has not yet traveled to distant parts of the body like the bladder, bowel, or other organs far from the pelvis. This is different from stage IV, where the disease spreads to distant sites. Stage III is considered locally advanced because the cancer remains confined to the pelvic area, even though it has moved beyond its original location in the lining of the uterus.[2][3]
The stage of cancer is determined through a combination of tests including tissue samples taken through endometrial biopsy (removal of a small piece of tissue from the lining of the uterus) or dilation and curettage (a procedure that opens the cervix and scrapes tissue from inside the uterus), imaging tests to see if cancer has spread, and examination of cancer cells under a microscope. Often, the final stage is not confirmed until after surgery, when doctors can remove and closely examine the tumor and nearby lymph nodes (small bean-shaped structures that are part of the body’s immune system).[2][9]
The Three Substages of Stage III
Stage III endometrial cancer is divided into three substages, labeled 3A, 3B, and 3C. These substages describe exactly where the cancer has spread within the pelvis. Lower letters and numbers represent less advanced disease, so stage 3A is less advanced than stage 3B or 3C.[2][3]
In stage 3A, the tumor has grown into the outer covering of the uterus, called the serosa (the smooth outer layer), or has spread to the ovaries or fallopian tubes. At this stage, cancer has not yet reached the lymph nodes or other parts of the body.[2][3]
Stage 3B means the cancer has spread to the vagina, the connective tissue surrounding the uterus called the parametrium (tissue that supports the uterus), or the membrane that surrounds the pelvic organs. Like stage 3A, the lymph nodes and distant body parts remain free of cancer.[2][3]
Stage 3C describes cancer that has spread to nearby lymph nodes. It is further divided into stage 3C1, where cancer has reached the pelvic lymph nodes, and stage 3C2, where cancer has spread to lymph nodes around a major blood vessel called the aorta. In both cases, the cancer has not spread to distant parts of the body.[2][3]
Risk Factors for Endometrial Cancer
Certain factors can increase the chance of developing endometrial cancer. Obesity is one of the most significant risk factors, as excess body fat can produce hormones that stimulate the growth of the uterine lining. Having metabolic syndrome (a cluster of conditions including high blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol levels) also raises the risk.[7][10]
Women who take estrogen alone without progesterone after menopause face increased risk, as estrogen can encourage the growth of the uterine lining. Taking tamoxifen, a medication used to prevent or treat breast cancer, can also increase the risk of endometrial cancer. Other factors include never having given birth, starting menstruation at an early age, entering menopause later in life, and having polycystic ovarian syndrome (a hormonal disorder causing enlarged ovaries with small cysts).[7][10]
A family history of endometrial cancer in a first-degree relative such as a mother, sister, or daughter increases risk. Certain genetic conditions, particularly Lynch syndrome (an inherited condition that increases the risk of several types of cancer), significantly raise the likelihood of developing endometrial cancer. Having a condition called endometrial hyperplasia (abnormal thickening of the uterine lining) and having type 2 diabetes are also associated with higher risk. Age is an important factor, as the chance of getting cancer increases as people get older.[7][10]
Symptoms That May Signal Stage III Disease
The most common symptom of endometrial cancer, including stage III, is unusual vaginal bleeding. This might be bleeding that occurs between menstrual periods, heavier bleeding than normal during periods, or any bleeding after menopause. Vaginal discharge that is not related to menstruation can also be a warning sign.[7][10]
Pain in the pelvic area is another symptom that should not be ignored. Some women experience difficult or painful urination, while others notice pain during sexual intercourse. These symptoms can be caused by endometrial cancer or by other conditions, which is why it is important to check with a doctor if any of these signs appear.[7][10]
Treatment Approaches for Stage III Endometrial Cancer
Surgery is the main treatment for stage III endometrial cancer in women who are otherwise healthy enough to undergo the procedure. The goal of surgery is to remove all visible cancer. This typically involves removing the uterus and cervix in a procedure called hysterectomy (surgical removal of the uterus), along with both ovaries and fallopian tubes. The surgeon may also remove the top portion of the vagina, some surrounding tissue, and lymph nodes in the pelvis. This extensive surgery is called a radical hysterectomy and is performed by a specialist called a gynecologic oncologist (a surgeon who specializes in cancers of the female reproductive organs).[3][15]
Some women may not be able to have surgery because they are not physically well enough, the cancer is too difficult to remove completely, or they choose not to have surgery. In these cases, other treatments may be offered. These can include chemotherapy to shrink the cancer before surgery, a combination of external and internal radiation therapy called brachytherapy (radiation treatment delivered from inside the body) for high-grade cancers, or hormone therapy (treatment that blocks hormones or lowers their levels) if surgery or radiation is not possible.[3][15]
Treatment After Surgery
Stage III endometrial cancer carries a high risk of coming back after surgery. For this reason, additional treatment is usually recommended. Women may receive external radiation therapy combined with chemotherapy, followed by more chemotherapy. Another option is chemotherapy followed by radiation therapy, or chemotherapy alone.[3][15]
Some patients may be eligible for newer treatments including immunotherapy (treatment that helps the immune system fight cancer) or targeted cancer drugs (medications that target specific characteristics of cancer cells). These options depend on individual circumstances and whether other treatments have already been tried. Possible combinations include immunotherapy with chemotherapy, immunotherapy alone, or immunotherapy combined with a targeted drug.[3][15]
A large study found that women with stage III uterine cancer who received combination chemotherapy and radiation therapy had different outcomes compared to those who received only one type of treatment. The choice of treatment depends on many factors including the specific substage, the type of cancer cells, how aggressive the cancer appears under the microscope, and the patient’s overall health and preferences.[12]
How the Body Changes with Stage III Disease
In stage III endometrial cancer, the normal function of the uterus and surrounding pelvic structures is disrupted by the spread of cancer cells. The cancer begins in the endometrium (the inner lining of the uterus) but has grown through the uterine wall and beyond. When cancer cells invade the outer covering of the uterus or spread to nearby organs like the ovaries, fallopian tubes, or vagina, they can interfere with the normal function of these structures.[2][9]
Cancer spread to lymph nodes means that cancer cells have entered the lymphatic system (a network of vessels and tissues that help fight infection and disease). Lymph nodes act as filters, but when cancer cells reach them, the nodes may become enlarged and less able to perform their protective function. The presence of cancer in pelvic lymph nodes or lymph nodes around the aorta indicates that cancer cells are traveling through the body’s drainage system, though they have not yet established themselves in distant organs.[2][9]
The physical presence of the tumor can cause symptoms by pressing on nearby structures, blocking normal pathways, or causing inflammation. Bleeding occurs when cancer cells disrupt the normal blood vessels in the uterine lining or invade blood vessel walls. Pain may result from the tumor pressing on nerves or stretching the tissues surrounding the uterus and other pelvic organs.[2][9]
