Sarcoma Metastatic
Sarcoma metastatic is a rare and serious condition where cancer that starts in the bones or soft tissues has spread to distant parts of the body, most commonly the lungs.
Table of contents
What is Metastatic Sarcoma?
Sarcoma refers to a broad group of cancers that start in the bones and soft tissues of the body[1]. Soft tissues include muscle, fat, blood vessels, nerves, tendons, and the tissue that surrounds joints[1]. When sarcoma spreads to areas in the body away from the location of the original tumor, doctors call it metastatic soft tissue sarcoma or stage 4 sarcoma[2].
Sarcomas are rare cancers, making up only 1% of all adult cancer diagnoses and about 15% of childhood cancer diagnoses[3]. In 2012, approximately 2,890 new cases of bone and joint cancer and 11,280 new cases of soft tissue cancer were estimated in the United States[4]. Although most sarcomas begin as localized disease, many show a strong tendency to spread, especially to the lungs, liver, bones, tissue under the skin, and lymph nodes[4].
- Muscle
- Fat
- Blood vessels
- Nerves
- Tendons
- Cartilage
- Ligaments
- Bone
How Sarcoma Spreads
In metastatic soft tissue sarcoma, cancer cells break away from the original, or primary tumor, and spread to other areas through the bloodstream or lymphatic system[2]. The lymphatic system is a network of vessels and organs that helps the body fight infection and remove waste. Even if soft tissue sarcoma spreads to another area, such as the lungs or bones, it is still considered soft tissue sarcoma rather than lung or bone cancer[2].
Around 83% of metastatic soft tissue sarcoma occurs in the lungs[2]. The lungs are the most common site for metastasis because cancer cells often travel through the bloodstream to this organ. About 50% of patients with high-grade sarcomas eventually develop lung metastases, and in 70% of these patients, the lungs remain the only organ with metastatic disease[10].
Around 25% of metastatic soft tissue sarcoma cases may occur after initial treatment for the primary tumor[2]. This means that even after successful treatment of the original cancer, some patients may experience the cancer returning and spreading to other parts of the body. About 10% of patients present with synchronous metastatic disease, meaning the cancer has already spread by the time of initial diagnosis[10].
Diagnosis
Doctors may use a biopsy to diagnose metastatic soft tissue sarcoma[2]. A biopsy is a procedure that removes a sample of tissue for testing in a laboratory. A core biopsy uses a wide needle to remove multiple tissue samples for laboratory testing and may be more accurate than a fine-needle procedure[2]. Doctors may use imaging tests, such as ultrasound, to help guide this procedure.
An incisional biopsy removes a tissue sample or part of a lump for laboratory testing[2]. Laboratory tests can help doctors gather specific information about the tissue sample when looking for signs of cancer. These tests examine the appearance and number of cells, certain genes and proteins, changes in chromosomes, and certain antigens, which are substances that trigger an immune response[2].
Doctors may also order several tests to help them stage cancer and find out if and where it has spread[2]. These tests include:
- Chest X-ray to look for lung metastases
- Blood tests, including a complete blood count and blood chemistry tests
- CT scan or MRI scan to create detailed images of inside the body
- PET scan, which identifies cancerous tumor cells in the body
Along with biopsy results, these tests can help doctors stage cancer and decide on appropriate treatment[2].
Treatment Options
Treatment depends on the specific type of soft tissue sarcoma but may involve surgery, chemotherapy, radiation therapy, and targeted therapies[2]. The goal of treatment is to remove as much of the cancer as possible and control its growth.
Surgery
Doctors may try to remove all or most of the primary and metastatic soft tissue sarcoma with surgery[2]. Surgery is most often used to control symptoms caused by the cancer rather than to treat the cancer itself[15]. In rare cases, surgery with wide local removal may be done to remove all of the cancer, including the metastases, when the cancer has only spread to a few places in the lungs[15]. Surgery for other types of metastases may be possible in certain cases.
Chemotherapy
Chemotherapy is usually offered for stage 4 soft tissue sarcoma to help control the growth and spread of the cancer because surgery cannot be done in most cases[15]. Chemotherapy uses drugs to destroy cancer cells. It is also used to relieve symptoms of advanced cancer. Chemotherapy is most often the first treatment and may be used along with radiation therapy[15].
For treating soft tissue sarcoma, chemotherapy may include the drugs doxorubicin and ifosfamide[2]. Doxorubicin is the standard chemotherapy drug used and is usually given alone. It may be given in combination with ifosfamide[15]. If these are not effective, people may receive gemcitabine and docetaxel[2]. Other chemotherapy drugs can be used if doxorubicin does not work[15].
Radiation Therapy
If surgery does not completely remove the cancer, people may also have radiation therapy to help shrink and destroy the tumors[2]. Radiation therapy uses high-energy rays to kill cancer cells. External radiation therapy is most often used. It is given alone or in addition to chemotherapy[15].
Stereotactic body radiation therapy, or SBRT, may be used to treat lung metastases when there are only a few small tumors and surgery cannot be done[15]. In certain cases, it may be used to treat metastases outside the lungs.
Targeted Therapy
Targeted therapy is used to help stop the cancer cells from growing, dividing, and spreading[15]. Pazopanib may be offered after chemotherapy for some types of soft tissue sarcoma. It is used when chemotherapy has already been given or the soft tissue sarcoma continues to grow within one year after treatment[15].
Outlook and Survival
Patients with metastasized soft tissue sarcoma generally have a poor prognosis[4]. The outlook depends on many factors, including the size of the tumor, the grade of the cancer, how deep the tumor is, where the cancer started, the type of tumor, the stage, and the person’s age[18].
The median survival for patients with metastatic sarcoma is 12 months[4]. However, in more recent studies with improved systemic treatment, a median overall survival of 16 to 17 months has been reported[10]. Stage 4 soft tissue sarcoma, or metastatic soft tissue sarcoma, has a poor prognosis[18].
While localized sarcomas can often be cured through surgery and often radiation, about half of metastatic sarcomas are resistant to all current treatment approaches[5]. This shows the extreme need for new therapeutic approaches. Complete responses to chemotherapy in cases where the cancer has spread to other organs are quite rare[14].
Several factors can affect prognosis. Low-grade soft tissue sarcomas are linked with a better prognosis because they are less likely to spread or come back than high-grade sarcomas[18]. Tumors that are 5 centimeters or smaller have a better prognosis than tumors larger than 5 centimeters[18]. People with soft tissue sarcoma who are under the age of 50 tend to have a better prognosis than those over the age of 50[18].
After completion of treatment, people go on a schedule to undergo several imaging scans per year to check if the tumor is coming back. This is called surveillance and lasts approximately 5 years[19].
