Uterine Leiomyosarcoma

Uterine leiomyosarcoma is a rare and aggressive cancer that develops in the muscle wall of the uterus, accounting for only 2% to 5% of all uterine cancers. Despite often being discovered in early stages, this challenging disease requires specialized treatment and long-term monitoring.

Table of contents

• What is uterine leiomyosarcoma?
• Who gets this disease?
• Signs and symptoms
• Causes and risk factors
• How is it diagnosed?
• Treatment options
• What to expect
• Follow-up care and monitoring

What is uterine leiomyosarcoma?

Uterine leiomyosarcoma, often shortened to uLMS, is a type of cancer that starts in the smooth muscle tissue of the uterus. It belongs to a larger group of cancers called soft tissue sarcomas, which are cancers that begin in the connective tissues of the body^[1].

This cancer is quite rare, making up only 2% to 5% of all cancers that occur in the uterus. Among uterine sarcomas specifically, leiomyosarcoma is the most common type, accounting for about 30% of all uterine sarcomas^[1][6].

Uterine leiomyosarcoma is considered an aggressive tumor, meaning it tends to grow quickly and can spread to other parts of the body. What makes this disease particularly challenging is its resistance to standard treatments. The cancer cells can travel through the bloodstream and spread to any soft tissue in the body^[1][2].

• Uterus (specifically the myometrium or muscle wall)

Who gets this disease?

Uterine leiomyosarcoma most commonly affects women in their 40s through their 60s. The peak incidence occurs around age 50 years^[6]. However, it can occur in younger women as well^[4].

Research has shown that this type of cancer is twice as common in Black women compared to white women^[4]. This is an important health disparity that healthcare providers and patients should be aware of.

Signs and symptoms

One of the challenging aspects of uterine leiomyosarcoma is that many women do not experience symptoms in the early stages of the disease. As the tumor grows, however, certain warning signs may appear^[3].

The most common symptoms include:

• Abnormal vaginal bleeding, including bleeding between menstrual periods or after menopause
• Pelvic pain or pressure
• Abdominal pain or bloating
• A feeling of abdominal fullness
• Frequent urination
• Vaginal discharge that doesn’t improve with medication
• A palpable mass (lump that can be felt) in the pelvis or vagina

General symptoms that can occur with many types of cancer may also appear, including:

• Unintended weight loss
• Fever
• Tiredness or fatigue
• Nausea and vomiting
• A general feeling of being unwell

It’s important to note that these symptoms can also be caused by many other, less serious conditions. However, if you experience any of these symptoms, especially abnormal vaginal bleeding after menopause or persistent pelvic pain, you should contact your healthcare provider^[2][4].

Causes and risk factors

Scientists don’t fully understand what causes uterine leiomyosarcoma. The cancer develops when cells in the smooth muscle of the uterus undergo changes in their DNA—the instructions that tell cells what to do. In healthy cells, DNA tells cells to grow and multiply at a controlled rate and to die at a set time. In cancer cells, these instructions become damaged, causing cells to grow out of control and avoid normal cell death^[3].

Several risk factors have been identified that may increase a woman’s chance of developing uterine leiomyosarcoma:

Prior pelvic radiation: Having received radiation therapy to the pelvis is a documented risk factor. This radiation may have been given for other cancers or, in some older cases, for benign uterine bleeding. The cancer can develop 5 to 25 years after the radiation treatment. This applies to 10% to 25% of cases^[6].

Tamoxifen use: Women who take the drug tamoxifen for breast cancer treatment or prevention face an increased risk. Tamoxifen has an estrogenic effect on the uterus, which may contribute to this risk. The increased risk appears to be associated with taking tamoxifen for five years or longer. Because of this risk, women taking tamoxifen should have regular pelvic examinations and should undergo endometrial biopsy (a test where a small tissue sample is taken from the uterine lining) if they experience any abnormal uterine bleeding^[6].

Some rare inherited genetic conditions have been linked to leiomyosarcoma, though not specifically to the uterine form. These include Gardner syndrome, Gorlin syndrome, hereditary retinoblastoma, Li-Fraumeni syndrome, neurofibromatosis type 1, tuberous sclerosis, and Werner syndrome^[2].

Another rare inherited condition, hereditary leiomyomatosis and renal cell carcinoma syndrome, may also increase risk^[4].

How is it diagnosed?

Diagnosing uterine leiomyosarcoma can be challenging because its symptoms are similar to those of more common, benign (non-cancerous) conditions, particularly uterine fibroids. Sometimes, the cancer is only discovered after a woman has surgery to remove what were thought to be fibroids^[4].

When a healthcare provider suspects uterine leiomyosarcoma, they will begin with a thorough evaluation:

Medical history and physical examination: Your doctor will ask about your symptoms, how long you’ve had them, and your medical history. They will perform a pelvic exam to check for any abnormal masses or signs of disease^[2][4].

Imaging tests: Several types of imaging tests can help visualize what’s happening inside your body:

• Transvaginal ultrasound: A probe inserted into the vagina uses sound waves to create images of the uterus
• CT scan (computed tomography): A specialized X-ray that creates detailed cross-sectional images of your body
• MRI (magnetic resonance imaging): Uses powerful magnets and radio waves to create detailed images of soft tissues
• PET scan (positron emission tomography): Can help identify areas of cancer throughout the body

If a mass is seen on imaging tests, a tissue biopsy will be required to make a definitive diagnosis. During a biopsy, a small sample of tissue is removed and examined under a microscope by a pathologist^[2][4].

Once uterine leiomyosarcoma is diagnosed, additional imaging tests of the chest, abdomen, and pelvis may be done to determine if the cancer has spread to other parts of the body^[1].

Treatment options

The treatment approach for uterine leiomyosarcoma depends on several factors, including the stage of the disease (how far it has spread), the size of the tumor, and the patient’s overall health and preferences.

Surgery

Surgery is the cornerstone of treatment for uterine leiomyosarcoma, especially when the disease is caught early and hasn’t spread. Surgical removal of the tumor offers the best chance for long-term survival^[1][4].

The most common surgical procedure is a total abdominal hysterectomy, which involves removing the entire uterus. Often, the fallopian tubes and ovaries are also removed in a procedure called bilateral salpingo-oophorectomy. The surgeon aims to remove all visible cancer and achieve “clear margins,” meaning there are no cancer cells at the edges of the removed tissue^[1].

Chemotherapy

The role of chemotherapy—drugs that kill cancer cells—in uterine leiomyosarcoma remains somewhat controversial, particularly for early-stage disease after surgery. Multiple clinical trials have failed to demonstrate a clear benefit on overall survival when chemotherapy is given after surgery in early-stage disease^[1][5].

However, chemotherapy is commonly used for:

• Advanced disease that has spread beyond the uterus
• Recurrent disease (cancer that has come back)
• Cases where surgery couldn’t remove all the cancer

The most commonly used chemotherapy regimens include:

• Doxorubicin-based chemotherapy
• The combination of gemcitabine and docetaxel

These regimens are considered the standard of care for first-line treatment of advanced or recurrent disease^[5].

Radiation therapy

Radiation therapy, which uses high-energy beams to kill cancer cells, is sometimes used in the treatment of uterine leiomyosarcoma. However, its role is limited and is typically reserved for specific situations, such as treating cancer that has spread to certain areas like bones or the brain, or for controlling symptoms^[2].

Targeted therapy and immunotherapy

Researchers are actively studying newer treatment approaches for uterine leiomyosarcoma, including targeted therapy (drugs that target specific features of cancer cells) and immunotherapy (treatments that help the immune system fight cancer). While progress has been made in therapy for advanced and recurrent disease, these remain areas of ongoing research^[1][5].

Clinical trials

Clinical trials test new treatments to find out if they are safe and effective. Many experts recommend considering clinical trials as a first option, particularly before starting standard chemotherapy treatments. Participating in clinical trials not only gives patients access to potentially promising new therapies but also helps advance treatment options for future patients^[1].

What to expect

The outlook for women with uterine leiomyosarcoma depends primarily on the stage of the disease at the time of diagnosis. The majority of patients—about 60%—are diagnosed with early-stage disease^[1].

Unfortunately, regardless of the stage at diagnosis, uterine leiomyosarcoma has a challenging prognosis. It is an aggressive tumor with a tendency to recur (come back) even after apparently successful treatment^[1].

For women with stage I and II disease (cancer confined to the uterus or nearby structures), the 5-year disease-free survival rates are approximately 76% and 60%, respectively. For more advanced disease (stage III and IV), where the cancer has spread further, the 5-year disease-free survival rates drop to about 45% and 29%^[5].

Several factors influence prognosis beyond just the stage:

• Mitotic count: A measure of how rapidly the cancer cells are dividing. Higher mitotic activity (more than 10 mitoses per 10 high-power fields) generally indicates a more aggressive cancer^[1]
• Tumor size
• Whether the cancer has spread to lymph vessels or blood vessels
• Whether clear surgical margins were achieved during surgery

It’s important to note that statistics represent averages and cannot predict what will happen to any individual patient. Some women with uterine leiomyosarcoma do well and live for many years after diagnosis.

Follow-up care and monitoring

After completing treatment for uterine leiomyosarcoma, regular follow-up care is essential. The cancer has a tendency to recur, with studies suggesting it returns in nearly 40% of cases. The risk is highest in the first five years after treatment, so this is when the most intensive monitoring occurs^[14].

A typical follow-up schedule might include:

• Appointments every 3 to 6 months for the first 2 to 3 years after treatment
• Appointments every 6 months for years 3 through 5
• Annual appointments after 5 years, continuing for the rest of your life

During follow-up visits, your healthcare team will:

• Ask about any symptoms you’re experiencing
• Perform a physical examination, checking for lumps, swelling, or other signs of cancer
• Order imaging tests such as CT scans, MRI, or chest X-rays to look for signs of cancer recurrence
• Address any side effects from your treatment

It’s crucial to report any new or concerning symptoms to your doctor right away, including:

• A new lump or swollen area
• Pain, tenderness, or pressure
• Unusual vaginal bleeding or discharge
• Changes in bladder or bowel habits
• Unexplained weight loss, fever, or fatigue

Even many years after being declared cancer-free (a status called NED, or “no evidence of disease”), uterine leiomyosarcoma can recur. This is why lifelong monitoring is recommended^[14].

Follow-up care also includes managing any long-term or late side effects of treatment, supporting your emotional well-being, and helping you maintain the best possible quality of life. Your healthcare team is there to support you throughout your journey with this disease.