Uterine sarcoma

Uterine sarcomas are forms of soft tissue sarcoma that develop in the uterus, or womb. The most common types of uterine sarcoma grow in the muscle of the uterus, also called the myometrium. Other types of these cancerous tumors form in the endometrium, the tissue that lines the uterus wall.

Uterine sarcomas tend to grow and metastasize (spread) more quickly than other, more common types of uterine cancer and endometrial cancer. They can also return after treatment. When that happens, some affect nearby pelvic lymph nodes and pelvic organs such as the vagina, bladder, rectum, ovaries, and fallopian tubes. Others affect more distant locations such as the liver or lungs.

Uterine sarcomas account for just 2 to 5 percent of uterine cancers, affecting two people per 100,000. They most often occur in women between 50 and 70. Black women tend to be diagnosed with uterine sarcoma more often.

These rare and complex tumors require prompt care from a knowledgeable team with experience in uterine sarcomas. At Penn Medicine’s Abramson Cancer Center, uterine sarcomas are treated by some of the nation’s most experienced providers, from our Sarcoma Program and the Gynecologic Oncology team. These experts work together to develop an optimal treatment plan for each patient.

Uterine sarcoma includes several distinct types of cancer:

• Uterine Leiomyosarcoma: Uterine leiomyosarcoma is the most common type of uterine sarcoma. It forms in the myometrium, or muscle layer, of the uterus and can grow and spread quickly. Black women get this form of uterine sarcoma twice as often as white women. The average age at diagnosis is 50.
• Endometrial Stromal Sarcoma: These tumors grow in the endometrium (uterine lining) in supportive tissue called stroma. They may be low-grade, meaning they are more likely to grow slowly. These low-grade tumors frequently need the hormones estrogen or progesterone to continuing growing. Other endometrial stromal sarcomas are high-grade, meaning they tend to grow quickly and pose more of a challenge.
• Undifferentiated Sarcoma: These less common tumors can develop in the myometrium or the endometrium. They grow and spread quickly.
• Adenosarcoma: Another uncommon uterine sarcoma, these tumors tend to grow slowly. They represent just 5 percent of uterine sarcomas.

Uterine sarcomas can cause a range of symptoms that can vary from one person to the next. These symptoms are similar to those of many non-cancerous conditions, so you should seek medical guidance if you experience:

• Feeling of fullness in the belly
• Irregular periods
• Pelvic pressure or pain
• More frequent urination
• Vaginal bleeding that’s not part of your normal period or that happens after menopause

Doctors often don’t know what causes uterine sarcoma to form. However, some factors may increase the risk of developing one.

Previous radiation therapy to the pelvis for another medical condition may make it more likely to eventually develop uterine sarcoma. Taking the hormone therapy tamoxifen to treat breast cancer can as well.

Some people also inherit genetic changes that raise their risk for developing uterine sarcoma, which include:

• Hereditary retinoblastoma: In addition to raising the risk for the eye cancer retinoblastoma, this syndrome increases the chances that certain soft tissue sarcomas may form, including uterine sarcoma.
• Li–Fraumeni syndrome (LFS): While LFS is mainly tied to rhabdomyosarcoma, it raises the risk for other soft tissue cancers, such as uterine sarcoma.

To diagnose a uterine sarcoma, our doctors perform a thorough exam and talk to you about your symptoms. Part of the evaluation includes a pelvic exam of the reproductive organs and a rectal exam.

To evaluate unusual bleeding, your doctor will often take a tissue sample from the lining of the uterus (endometrium). This may be done by scraping some cells during a procedure called dilation and curettage (D and C) or with a minimally invasive biopsy.

These tests are not able to reach uterine leiomyosarcoma unless the cancer has started in the endometrium or grown into it. For suspicious tumors involving only the wall of the uterus, we may recommend a hysterectomy (removal of the uterus) to make a diagnosis. After the hysterectomy, one of our specialized pathologists analyzes the tumor to see if cancer is present.

If uterine sarcoma is confirmed through tissue sampling or hysterectomy, your doctor will recommend imaging tests to check for signs that the cancer has spread and stage the cancer.

Uterine sarcoma treatment at Penn usually begins with removing the tumor. Doing so often requires taking out the uterus and cervix during a hysterectomy. We may do this with a minimally invasive surgery or an open procedure. In some cases, our surgeons may also recommend removing the ovaries, depending on the type of uterine sarcoma and other factors such as age.

Next steps depend on the type of uterine sarcoma. For some cancers, our team may follow you closely to watch for signs of cancer recurrence. This is often the case with sarcomas that did not grow outside the uterus.

For other uterine sarcomas, our team may recommend radiation therapy, chemotherapy, or hormone-blocking medications.

Researchers are also looking to develop additional treatment options through sarcoma clinical trials. Possible avenues include targeted therapy aimed at cancer growth pathways or immunotherapy to harness the immune system.

At Penn Medicine, our team tests many uterine sarcomas for genetic changes that could make them treatable with newer therapies.