Uterine sarcomas (cancers arising from bone or soft tissue) are a very rare form of uterine cancer that develop in muscles (myometrium or connective tissue stroma) of the uterus. The uterus is a pear-shaped organ of the female reproductive system where fetal growth and development occur.
The uterus is made up of three layers: the endometrium, myometrium, and perimetrium (mucus layer protecting the uterus). The endometrium is the inner lining of the uterus, and is the layer that grows thick and sheds when fertilisation does not occur. This occurs monthly in a process known as menstruation. Cancers that develop in the endometrium are much more common, and are called endometrial cancers. For more information on endometrial cancers, please visit the Rare Cancers Australia Endometrial (uterine) cancer page.
The myometrium is the muscular, middle layer that makes up most of the uterus. It is responsible for holding the structure of the uterus, expanding to enable fetal growth, and inducing uterine contractions during childbirth. Cancers of the myometrium are considered to be very rare.
Uterine sarcomas are most common in post-menopausal women who are over 60 years old, however it can affect anyone with a uterus – including pre-menopausal women, teenagers, transgender men, non-binary individuals, and intersex people – at any age.
Types of Uterine Sarcomas
There are three different types of uterine sarcomas, which are categorised by the types of cells the cancer originates from.
Leiomyosarcomas
Leiomyosarcomas are the most common form of uterine sarcoma, and develop from the smooth muscle cells of the myometrium. They are often aggressive, often metastasise, and generally have a high recurrence rate. However, leiomyosarcomas can have a good prognosis when caught early. For more information on leiomyosarcomas, please refer to the Rare Cancers Australia Leiomyosarcoma page.
Endometrial Stromal Sarcoma
Endometrial stromal sarcomas are rare malignancies that develop in the connective tissue (or stroma) of the endometrium. These tumours are most often found in pre-menopausal women between the ages of 40 -50. Endometrial stromal tumours are usually non-aggressive, are relatively slow growing, and may have a good prognosis when caught early.
Undifferentiated Uterine Sarcoma
Undifferentiated uterine sarcomas are rare malignancies that can start in either the endometrium or the myometrium. This type of cancer is often considered to be aggressive, often metastasise and may have high recurrence rates. Unfortunately, undifferentiated uterine sarcomas may not have as good of a prognosis as other uterine sarcomas.
Rare types of Uterine Sarcoma
These types of cancers are considered to be very rare:
- Uterine carcinosarcoma (a mixed uterine cancer with features of endometrial cancers and uterine sarcomas).
- Uterine adenosarcoma (a mixed uterine cancer with features of benign tumours (adenomas) and uterine sarcomas).
Treatment
If a uterine sarcoma is detected, it will be staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.
FIGO Staging System
Gynaecological cancers, such as uterine sarcomas, can be staged using the Federation of Gynaecology and Obstetrics (FIGO) system from stage I to IV:
- Stage I: cancer cells are confined to the uterus only. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby organs in the pelvis, such as the ovaries, fallopian tubes, bladder and/or bowel. This is also known as localised cancer.
- Stage III: the cancer has become larger and has spread beyond the pelvis into the lining of the abdomen (peritoneum). Lymph nodes are also often affected. This is also known as advanced or metastatic cancer.
- Stage IV: the cancer has spread to more distant organs, such as the lungs or the liver. This is also known as advanced or metastatic cancer.
TNM Staging System
The TNM system can also be used to classify a uterine sarcoma. The TNM system is comprised of:
- T (tumour) indicates the size and depth of the tumour.
- N (nodes) indicates whether the cancer has spread to nearby lymph nodes.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment Options
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for uterine sarcomas may include:
- Surgery, potentially including:
- Total hysterectomy (removal of the uterus).
- Bilateral salpingo-oophorectomy (removal of both ovaries and fallopian tubes).
- Unilateral salpingo-oophorectomy (removal of one ovary and fallopian tube).
- Lymphadenectomy (removal of affected lymph nodes).
- Trachelectomy (removal of part or all of the cervix).
- Chemotherapy.
- Radiation therapy.
- Hormone therapy.
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia treatment options page.
Uterine Sarcoma Treatment and Fertility
Treatment for uterine sarcoma may make it difficult to become pregnant. If fertility is important to you, discuss your options with your doctor and a fertility specialist prior to the commencement of treatment.
Risk factors
While the cause of uterine sarcomas remains unknown, the following factors may increase the risk of developing the disease:
- Having had radiation for a cancer in the pelvic area.
- Having used the Tamoxifen hormone therapy drug for breast cancer over a long period of time (5+ years).
- Having a genetic mutation in the retinoblastoma tumour suppressor gene (RB1).
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Early symptoms
Symptoms of a uterine sarcoma may include:
- Unusual bleeding in-between periods.
- Bleeding after menopause.
- A mass or lump in the vagina.
- Abdominal pain.
- Pelvic pain.
- Feeling of abdominal fullness.
- Frequent urination.
- Abnormal vaginal discharge.
- Unexplained weight loss.
Not everyone with the symptoms above will have cancer but see your general practitioner (GP) if you are concerned.
Diagnosis/diagnosing
If your doctor suspects you have a uterine sarcoma, they will order a range of diagnostic tests to confirm the diagnosis, and refer you to a specialist for treatment.
Physical examination
Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities.
Pelvic examination
The doctor will inspect the abdomen for any swelling or masses, followed by your genitalia. The doctor will then insert two fingers into your vagina while simultaneously pressing on your abdomen with their other hand to feel your uterus and ovaries. Following this, the doctor may use a device called a speculum into your vagina, which will separate the vaginal walls and allow viewing of your vaginal canal and cervix for any visible abnormalities. You many request a family member, friend, or nurse to be present during this exam.
Imaging & blood tests
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), transvaginal ultrasound and/or positron emission tomography (PET scan), depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.
Biopsy
A biopsy is a procedure that is undertaken to remove a sample of tissue or cells from the body to be tested in a laboratory to detect any abnormalities. To detect uterine sarcomas, a biopsy can be performed in a few different ways:
Endometrial (Pipelle) Biopsy
This type of biopsy can be done in a specialist’s office and can be done without anaesthesia. In this procedure, a long, thin plastic tube (pipelle) is inserted into your vagina and through the cervix to reach the uterus. Cells are then gently extracted from the uterine lining, which will be sent to a laboratory for analysis. This procedure only takes a few minutes, but may cause some discomfort similar to period cramps.
Hysteroscopy & D&C (Dilation and Curettage)
If the results of the endometrial biopsy are unclear, your doctor may request another biopsy to be performed during a hysteroscopy. This procedure involves inserting a thin, flexible tube with a tiny light and camera (hysteroscope) into your vagina and through the cervix to reach the uterus. A specialist is then able to examine the endometrium for any abnormalities. To take a biopsy, an additional procedure called a dilation and curettage (D&C) may be performed, where your doctor dilates your cervix using surgical instruments and extracts some endometrial tissue for analysis. Both procedures are performed as a day surgery in a hospital under general anaesthetic, and may cause some cramping and light bleeding for several days after.
Prognosis (Certain factors affect the prognosis and treatment options)
While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on stage, rate/depth of tumour growth, susceptibility to treatment, age, overall fitness and medical history. Generally, early-stage uterine cancers have a good prognosis and survival rates. However, if the cancer is advanced and has spread, the prognosis may not be as good and there may be a higher risk of cancer recurrence.
References
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.