Soft tissue sarcomas

Overview

Soft tissue sarcoma is a type of cancer that begins in the soft tissues. Soft tissues connect, support and surround other body structures. The soft tissues include muscle, fat, blood vessels, nerves, tendons and the lining of your joints.

Many types of soft tissue sarcoma exist. Some types are more likely to affect children, while others affect mostly adults.  Soft tissue sarcoma can occur anywhere in your body, but the most common types occur in the abdomen and in the arms and legs.

Symptoms

In their early stages, soft-tissue sarcomas usually do not cause symptoms. Because soft tissue is relatively elastic, tumors can grow rather large, pushing aside normal tissue, before they are felt or cause any problems. The first noticeable symptom is usually a painless lump or swelling. As the tumor grows, it may cause other symptoms, such as pain or soreness, as it presses against nearby nerves and muscles. If in the abdomen it can cause abdominal pains commonly mistaken for menstrual cramps, indigestion, or cause constipation.

Causes

In most cases, it's not clear what causes soft tissue sarcoma. In general, cancer occurs when cells develop errors (mutations) in their DNA. The errors make cells grow and divide out of control. The type of cell that develops the mutation determines what type of soft tissue sarcoma such as:

• Alveolar soft part sarcoma
• Angiosarcoma
• Clear cell sarcoma
• Dermatofibrosarcoma protuberans
• Desmoplastic small round cell tumor
• Epithelioid hemangioendothelioma
• Epithelioid sarcoma
• Extrarenal rhabdoid tumor
• Fibrosarcoma
• Gastrointestinal stromal tumor (GIST)
• Hemangiosarcoma
• Infantile fibrosarcoma
• Inflammatory myofibroblastic tumor
• Kaposi's sarcoma
• Leiomyosarcoma
• Liposarcoma
• Lymphangiosarcoma
• Malignant fibrous histiocytoma
• Malignant peripheral nerve sheath tumor
• Myofibrosarcoma
• Myxofibrosarcoma
• Neurofibrosarcoma
• Perivascular epitheliod cell tumor (PEComa)
• Rhabdomyosarcoma
• Synovial sarcoma
• Undifferentiated, unclassified soft tissue sarcomas

Prevention

Factors that may increase risk of sarcoma include:

Inherited syndromes: A risk of soft tissue sarcoma can be inherited from your parents. Genetic syndromes that increase your risk include hereditary retinoblastoma, Li-Fraumeni syndrome, familial adenomatous polyposis, neurofibromatosis, tuberous sclerosis and Werner syndrome.

Chemical exposure: Being exposed to certain chemicals, such as herbicides, arsenic and dioxin, may increase the risk of soft tissue sarcomas.

Radiation exposure: Previous radiation treatment for other cancers can increase the risk of soft tissue sarcomas.

Diagnosis

Tests and procedures used to diagnose soft tissue sarcoma include:

• Imaging tests: Imaging tests, such as X-rays, computerized tomography (CT) scans, magnetic resonance imaging (MRI) and positron emission tomography (PET), may be used to evaluate the area of concern.
• Removing a sample of tissue for testing: Your doctor may perform a biopsy procedure to remove a sample of the suspected sarcoma for testing in a lab. To remove the sample, your doctor may use a long, thin needle. Sometimes a biopsy sample is removed during surgery.

Prognosis

While aggressive treatment is usually necessary, most children with rhabdomyosarcoma will achieve long-term survival. Cure depends on the specific type of tumor, its location, and the amount that has spread. Complications:

• Complications from chemotherapy
• Location in which surgery is not possible
• Metastasis

Treatment

In general, treatment for soft-tissue sarcomas depends on the stage of the cancer, which is based on the size and grade of the tumor, and whether the cancer has spread to the lymph nodes or other parts of the body (metastasized). Treatment options for soft-tissue sarcomas include surgery, radiation therapy, and chemotherapy.

• Surgery is the most common treatment for soft-tissue sarcomas. If possible, the doctor will remove the cancer and a safe margin of the healthy tissue around it. It is important to obtain a margin free of tumor to decrease the likelihood of local recurrence and give the best chance for eradication of the tumor. Depending on the size and location of the sarcoma, it may, rarely, be necessary to remove all or part of an arm or leg.
• Radiation therapy may be used either before surgery to shrink tumors or after surgery to kill any cancer cells that may have been left behind. In some cases, it can be used to treat tumours that cannot be surgically removed. In multiple studies, radiation therapy has been found to improve the rate of local control, but has not had any influence on overall survival.
• Chemotherapy may be used with radiation therapy either before or after surgery to try to shrink the tumor or kill any remaining cancer cells. The use of chemotherapy to prevent the spread of soft-tissue sarcomas has not been proven to be effective. If the cancer has spread to other areas of the body, chemotherapy may be used to shrink tumors and reduce the pain and discomfort they cause, but is unlikely to eradicate the disease. 
• Targeted drugs block specific abnormal signals present in sarcoma cells that allow them to grow. Some of the FDA approved drugs to treat soft tissue sarcomas include:
• Pazopanib (Votrient) - Advanced soft tissue sarcoma (STS) who have received prior chemotherapy
• Eribulin Mesylate (Halaven) - Treatment of patients with unresectable or metastatic liposarcoma who have received a prior anthracyclne-containing regimen
• Trabectedin (Yondelis) - For the treatment of patients with unresectable or metastatic liposarcoma or leiomyosarcoma who received a prior anthracycline-containing regimen
• Olaratumab (Lartruvo) -  In combination with doxorubicin, for the treatment of adult patients with soft tissue sarcoma (STS) with a histologic subtype for which an anthracycline-containing regimen is appropriate and which is not amenable to curative treatment with radiotherapy or surgery.

 Many new targeted drugs are being studied and meanwhile several have received orphan designation.