Uterine sarcomas (cancers arising from bone or soft tissue) are a very rare form of uterine cancer that develop in muscles 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 prognosisto predict how a disease/condition may progress and what the outcome might be 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 benignnot cancerous, can grow but will not spread to other body parts tumours (adenomas) and uterine sarcomas).
Treatment
If a uterine sarcoma is detected, it will be staged and graded based on size, metastasis, 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 nodessmall bean-shaped structures that filters harmful substances from lymph fluid are also often affected. This is also known as advancedat a late stage, far along 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 (node) 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 testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, 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:
- Hysterectomycomplete or partial removal of the uterus.
- Bilateral salpingo-oophorectomy.
- Unilateral salpingo-oophorectomy.
- Lymphadenectomysurgical removal of lymph node(s).
- Trachelectomycomplete or partial removal of the cervix.
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells.
- Hormone therapymedication that alters the levels of certain hormones in the body, such as oestrogen and progesterone.
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
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.
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.
- Polyuriafrequent 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
If your doctor suspects you have a uterine sarcoma, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Pelvic examination.
- Imaging tests, potentially including:
- MRI (magnetic resonance imaging)a type of medical imaging that uses radiowaves, a strong magnet and computer technology to create detailed images of the body.
- CT (computed tomography) scana type of medical imaging that uses x-rays and computer technology to create detailed images of the body.
- Transvaginal ultrasounda type of pelvic ultrasound that involves inserting a device (known as a transducer) into the vagina to produce sound waves and create images of internal female reproductive organs in greater detail.
- Pelvic ultrasounda type of medical imaging that uses soundwaves to create detailed images of the body .
- Blood teststesting done to measure the levels of certain substances in the blood.
- Hysteroscopyexamination of the uterus with a small, flexible instrument known as a hysteroscope.
- Biopsyremoval of a section of tissue to analyse for cancer cells, potentially including:
- Endometrial (pipelle) biopsya procedure that involves inserting a long, thin plastic tube (pipelle) into the vagina and through the cervix to gently extract a sample of tissue from the uterus for testing.
- Dilation and curettagea minor surgical procedure that involves dilating the cervix and scraping out the lining of the uterus (endometrium) with a small, sharp instrument (curette) (D&C).
