What's the Difference Between Uterine Cancer and Fibroids?
- Uterine cancer occurs when cancer cells form in the muscles of the uterus or tissues that support the uterus. Cancers that develop in the uterus are types of sarcomas.
- A uterine fibroid is a common, benign (not cancerous) tumor that occurs on the smooth muscle of the wall of the uterus. Fibroids can develop inside the uterus, within the uterine muscle, or on the outside of the uterus.
- Symptoms of uterine cancer and uterine fibroids that are similar include pain or feeling of fullness in the abdomen or frequent urination.
- Symptoms of uterine cancer that are different from uterine fibroids include abnormal vaginal bleeding (bleeding that is not part of a menstrual period, bleeding after menopause), or a mass in the vagina.
- Fibroids may not have any accompanying symptoms. When symptoms of fibroids are present, they may include increased menstrual bleeding, urinary urgency, constipation, pelvic pressure, increased waist size (clothing size may go up but not due to weight gain), infertility, and a pelvic mass.
- Causes of uterine sarcoma include exposure to X-rays, past radiation treatment to the pelvic area, and treatment with tamoxifen for breast cancer.
- The cause of fibroids is unknown. Fibroids are often hereditary. Other risk factors include African ethnicity, being overweight or obese, never having given birth, and onset of the menstrual period before age 10.
- Treatment for uterine sarcoma includes surgery, radiation therapy, chemotherapy, and hormone therapy. Clinical trials may also be available.
- Treatment for fibroids depends on the size and location of the fibroids, the patient’s symptoms, and other factors. In most cases when there are no symptoms or the fibroids are small, no treatment is needed. When treatment is required it may involve dilation and curettage (D&C), hormonal medications such as oral contraceptives, nonsteroidal anti-inflammatory drugs (NSAIDs), gonadotropin releasing hormone agonists, or RU-486. Other procedures to remove or shrink fibroids include surgery (myomectomy), hysterectomy, uterine artery embolization, and magnetic resonance guided focused ultrasound.
- Many factors affect the prognosis and survival rate for uterine sarcomas. The outlook depends on the stage of the cancer, the size and type of the tumor, the patient’s overall heath, and whether the cancer is newly diagnosed or has recurred.
- The prognosis for uterine fibroids depends on the severity of the fibroid(s) prior to treatment and the chosen treatment. Fibroids may affect fertility and may be symptomatic during pregnancy. In rare instances fibroids may become cancerous.
What Is Uterine Cancer?
Uterine sarcoma is a disease in which malignant (cancer) cells form in the muscles of the uterus or other tissues that support the uterus.
The uterus is part of the female reproductive system. The uterus is the hollow, pear-shaped organ in the pelvis, where a fetus grows. The cervix is at the lower, narrow end of the uterus, and leads to the vagina. Uterine sarcoma is a very rare kind of cancer that forms in the uterine muscles or in tissues that support the uterus. Uterine sarcoma is different from cancer of the endometrium, a disease in which cancer cells start growing inside the lining of the uterus.
Types of uterine sarcoma include:
- Leiomyosarcoma (LMS) - tumors start in the muscular wall of the uterus (the myometrium)
- Endometrial stromal sarcoma (ESS) - tumors start in the supporting connective tissue (stroma) of the lining of the uterus (the endometrium)
- Undifferentiated sarcoma – may start in the endometrium or the myometrium
What Are Uterine Fibroids?
A uterine fibroid is the most common benign (not cancerous) tumor of a woman's uterus (womb). Fibroids are tumors of the smooth muscle found in the wall of the uterus.
They can develop within the uterine wall itself or attach to it. They may grow as a single tumor or in clusters. Uterine fibroids can cause excessive menstrual bleeding, pelvic pain, and frequent urination.
- These growths occur in up to 50% of all women and are one leading cause of hysterectomy (removal of the uterus) in the United States. An estimated 600,000 hysterectomies are performed in the US annually, and at least one-third of these procedures are for fibroids. Medications and newer, less invasive surgical treatments are now available to help control the growth of fibroids.
- Fibroids start in the muscle tissues of the uterus. They can grow into the uterine cavity (submucosal), into the thickness of the uterine wall (intramuscular), or on the surface of the uterus (subsersoal) into the abdominal cavity. Some may occur as pedunculated masses (fibroids growing on a stalk off of the uterus).
- Although these tumors are called fibroids, this term is misleading because they consist of muscle tissue, not fibrous tissue. The medical term for a fibroid is leiomyoma, a type of myoma or mesenchymal tumor.
What Are the Signs and Symptoms of Uterine Cancer vs. Uterine Fibroids?
Signs of uterine sarcoma include abnormal bleeding. Abnormal bleeding from the vagina and other signs and symptoms may be caused by uterine sarcoma or by other conditions.
Check with your doctor if you have any of the following:
- Bleeding that is not part of menstrual periods.
- Bleeding after menopause.
- A mass in the vagina.
- Pain or a feeling of fullness in the abdomen.
- Frequent urination.
Most fibroids, even large ones, produce no symptoms. These masses are often found during a regular pelvic examination.
When women do experience symptoms, the most common are the following:
- an increase in menstrual bleeding, known as menorrhagia, sometimes with blood clots;
- pressure on the bladder, which may cause frequent urination and a sense of urgency to urinate and, rarely, the inability to urinate;
- pressure on the rectum, resulting in constipation;
- pelvic pressure, "feeling full" in the lower abdomen, lower abdominal pain;
- increase in size around the waist and change in abdominal contour (some women may need to increase their clothing size but not because of a significant weight gain);
- infertility, which is defined as an inability to become pregnant after 1 year of attempting to get pregnant; and/or
- a pelvic mass discovered by a health care practitioner during a physical examination.
What Causes Uterine Cancer vs. Fibroids?
Being exposed to X-rays can increase the risk of uterine sarcoma.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk with your doctor if you think you may be at risk. Risk factors for uterine sarcoma include the following:
- Past treatment with radiation therapy to the pelvis.
- Treatment with tamoxifen for breast cancer. If you are taking this drug, have a pelvic exam every year and report any vaginal bleeding (other than menstrual bleeding) as soon as possible.
The exact reasons why some women develop fibroids are unknown. Fibroids tend to run in families, and affected women often have a family history of fibroids. Women of African descent are two to three times more likely to develop fibroids than women of other races.
Fibroids grow in response to stimulation by the hormone estrogen, produced naturally in the body. These growths can show up as early as age 20, but tend to shrink after menopause when the body stops producing large amounts of estrogen.
Fibroids can be tiny and cause no problems, or they also can grow to weigh several pounds. Fibroids generally tend to grow slowly.
The following factors have been associated with the presence of fibroids:
- Being overweight, obesity
- Never having given birth to a child (called nulliparity)
- Onset of the menstrual period prior to age 10
- African American heritage (occurring 3-9 times more often than in Caucasian women)
What Is the Treatment for Uterine Cancer vs. Fibroids?
Different types of treatments are available for patients with uterine sarcoma. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer.
When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Four types of standard treatment are used:
Surgery is the most common treatment for uterine sarcoma, as described in the Stages of Uterine Sarcoma section of this summary.
Even if the doctor removes all the cancer that can be seen at the time of the surgery, some patients may be given chemotherapy or radiation therapy after surgery to kill any cancer cells that are left. Treatment given after the surgery, to lower the risk that the cancer will come back, is called adjuvant therapy.
Radiation therapy is a cancer treatment that uses high energy X-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy:
- External radiation therapy uses a machine outside the body to send radiation toward the cancer.
- Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer.
The way the radiation therapy is given depends on the type and stage of the cancer being treated. External and internal radiation therapy are used to treat uterine sarcoma, and may also be used as palliative therapy to relieve symptoms and improve quality of life.
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the cerebrospinal fluid, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). The way the chemotherapy is given depends on the type and stage of the cancer being treated.
Hormone therapy is a cancer treatment that removes hormones or blocks their action and stops cancer cells from growing. Hormones are substances produced by glands in the body and circulated in the bloodstream.
Some hormones can cause certain cancers to grow. If tests show the cancer cells have places where hormones can attach (receptors), drugs, surgery, or radiation therapy is used to reduce the production of hormones or block them from working.
Treatment for uterine sarcoma may cause side effects.
Patients may want to think about taking part in a clinical trial. For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.
Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.
Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.
Patients can enter clinical trials before, during, or after starting their cancer treatment.
Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.
Clinical trials are taking place in many parts of the country.
Follow-up tests may be needed.
Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. Some tests will be repeated in order to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests.
Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.
Treatment for fibroids depends on the symptoms, the size and location of the fibroids, age (how close the person is to menopause), the patient's desire to have children, and the patient's general health.
In most cases, treatment is not necessary, particularly if the woman has no symptoms, has small tumors, or has gone through menopause. Abnormal vaginal bleeding caused by fibroids may require surgical scraping of the uterine cavity in a procedure known as a dilation and curettage (D&C). If no malignancy (cancer) is found, this bleeding often can be controlled by hormonal medications. The following treatment options should be discussed with a health care practitioner.
The woman's doctor may follow the size and growth of the fibroids over time to make sure no indicators of cancer are present. If the person does not have symptoms such as vaginal bleeding or pelvic pain, and if the fibroid is not growing rapidly, no treatment may be needed. Some patient's may, however, require more frequent pelvic exams, such as every 6 months, to check on changes with the fibroid(s).
Patients may be given nonsteroidal anti-inflammatory drugs, oral contraceptives (birth control pills), gonadotropin releasing hormone agonists, or RU-486.
- Nonsteroidal anti-inflammatory agents, such as ibuprofen (Advil is one example), have been shown to relieve pelvic pain associated with fibroids.
- Oral contraceptive pills are also commonly used in women with fibroids. They often decrease perceived menstrual blood flow and help with pelvic pain.
- Gonadotropin releasing hormone (GnRH) agonists are medications that act on the pituitary gland to decrease estrogen produced by the body. A decrease in estrogen causes fibroids to decrease in size. This type of medication often is used prior to surgery to shrink the fibroid, to decrease the amount of blood loss during surgery, or to improve preoperative blood count. The size of the fibroid can be reduced by 50% in three months with of this type of therapy. But fibroids can regrow once treatment is stopped. Long-term therapy with these medications is limited by the side effects of low estrogen (much like menopause), which include decreased bone density, osteoporosis, hot flashes, and vaginal dryness.
- The antihormonal drug RU-486 (mifepristone) has also been shown to reduce fibroid size by about half. This drug has also been shown to reduce pelvic pain, bladder pressure, and lower back pain. Low doses of this drug may reduce the size of fibroids in preparation for surgery to remove them. It may also help some patients avoid surgery entirely by shrinking the fibroids and the problems they are causing. Side effects related to low estrogen, seen with GnRH analogs, may be less common. RU-486 can induce miscarriage, so this medication should be used with caution if a woman is trying to conceive.
- The drug danazol (Danocrine) has been used to reduce bleeding in women with fibroids, since this drug causes menstruation to cease, but it does not shrink the size of fibroids. Danazol is an androgenic (male) hormonal drug that can cause serious side effects including weight gain, muscle cramps, decreased breast size, acne, hirsutism (inappropriate hair growth), oily skin, mood changes, depression, decreased high density lipoprotein (HDL or 'good cholesterol') levels, and increased liver enzyme levels.
- Another new drug may be useful in treating some uterine fibroids. It is a progesterone receptor modulator named EllaOne. It is used as an emergency contraception drug, but was found to shrink fibroids and reduce bleeding associate with fibroids.
- Surgery options for treatment have both risks and benefits. Be sure to discuss these risks and benefits with the doctor. Some treatment options may not be right for a woman because of the characteristics of the fibroids or other health factors.
- Myomectomy is the surgical removal of the fibroids only. This can be accomplished through hysteroscopy, laparoscopy, or, less frequently, an open procedure (an incision in the abdomen). The surgical approach depends on the size and location of the fibroid. Pretreatment with GnRH analogs has been shown to decrease blood loss and operative time in women undergoing myomectomy. Myomectomy has also been shown to have a decreased likelihood of injury to the bowel, bladder, or ureter than hysterectomy. The uterus is left intact in this type of procedure, and the patient may be able to become pregnant.
- Hysterectomy is the surgical removal of the uterus (and fibroids). It is the most commonly performed surgical procedure in the treatment of fibroids and is considered a cure. Depending on the size of the fibroid, hysterectomy can be performed with incisions through the vagina or abdomen. In some cases the procedure may be performed using laparoscopy. Use of GnRH agonists can reduce the size of the fibroid to allow less invasive surgical techniques. In past experience, less blood loss has occurred using hysterectomy than myomectomy. Hysterectomy with removal of the Fallopian tubes and ovaries (called a salpingo-oophorectomy) may be indicated if there is suspicion of cancer or if ovarian masses are present.
- Uterine artery embolization, or clotting of the arterial blood supply to the fibroid, is an innovative approach that has shown promising results. This procedure is done by inserting a catheter (small tube) into an artery of the leg (the femoral artery), using special X-ray video to trace the arterial blood supply to the uterus, then clotting the artery with tiny plastic or gelatin sponge particles the size of grains of sand. This material blocks blood flow to the fibroid and shrinks it. This method may prove to be a good option for women if other methods have not worked, she does not want surgery, or may not be good candidates for surgery. A specialist known as an interventional radiologist performs this procedure.
- A newer procedure has also shown promise: magnetic resonance guided focused ultrasound. In this procedure, MRI is used to guide an ultrasound beam that heats the fibroids and helps to heat and destroy small areas of fibroid tissue.
What Is the Prognosis for Uterine Cancer vs. Fibroids?
Certain factors affect prognosis (chance of recovery) and treatment options. The prognosis (chance of recovery) and treatment options depend on the following:
- The stage of the cancer.
- The type and size of the tumor.
- The patient's general health.
- Whether the cancer has just been diagnosed or has recurred (come back).
Treatment success and future outcome depend on the severity of the fibroid or fibroids prior to treatment and the chosen treatment. Fibroids may affect fertility, but this depends on the size and location of the fibroids. Many women with fibroids are older than 35 years. This and other factors such as decreased egg quality and decreased ovulation contribute to their inability to become pregnant.
Fibroids rarely turn into cancer. This is more likely to occur in women after menopause. The most common warning sign of cancer is a rapidly growing tumor that requires surgery.
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