Soft Tissue Sarcoma (STS)
Soft Tissue Sarcomas (STS) are a group of cancers that originate from the basic elements of body tissues like: muscle, vessels, fatty tissue, fibrous tissue, etc. They may involve any part or any organ of the body. They account for about 1% of all cancers in USA and roughly 6,000 new cases are diagnosed each year in the United states. Average age at the time of diagnosis is 40-60 years. The incidence of STS is higher among persons with certain heritable cancers like Retinoblastoma, etc. Sarcomas are more common in New Zealand than in the United States.
Cause
The actual cause of these cancers is unknown; however, some environmental factors play a role in their development. Exposure to radiation, chemotherapy and certain chemicals can increase the risk of developing such tumors. Thorotrast is a radioisotope that was used for angiography and was found to cause certain cancers, specially in liver. Some agricultural pesticides and herbicides (dioxin) have been linked to these tumors.
Signs and symptoms
Signs and symptoms depend on the origin and location of the cancer.
- Arms or legs - Patients may notice a swelling and a lump
- Abdomen - These cancers can grow for a long time without causing any problems. Most patients are diagnosed in advanced stages and present with any of the following signs: stomach pain, weight loss, nausea or vomiting.
- Inside bowels, involving stomach, small intestines and large bowel and causing bowel obstruction
Diagnosis
These cancers can be detected on physical examination of the involved area. Any suspicious lump should be biopsied. X-rays, CT scan or other studies might be needed to locate the cancer, e.g., endoscopy of the stomach, which allows taking a biopsy at the same time. The STS can refer to any of the following tumors:
- Rhabdomyosarcoma: tumors of voluntary muscles, like the muscles of legs
- Leiomyosarcoma: tumors of involuntary muscles, like the muscles of bowels,
- Chondrosarcoma: tumors cartilage tissue
- Liposarcoma: tumors of fatty tissue
- Angiosarcoma: tumors of blood vessels
- Synovial Sarcoma: tumors of tissues that surround the joints
- Fibrosarcoma: tumors of fibrous tissue
- Lymphangiosarcoma: tumors of lymphatic vessels
- Fibrous Hystiocytoma: tumors of connective tissue ( most common form of STS)
- Retroperitoneal Sarcomas: tumors of the far back of abdomen (refers to the location of tumor and not the type)
These tumors are categorized into three grades (low, intermediate and high). The potential for metastasis ranges from 5% for low grade tumors to 60% for high grade tumors.
Treatment
STS remain as a very difficult group of cancers to treat, mostly due to the various presentations, sites of involvement and their diversity in terms of their pathology, patterns of spread. In treatment of these tumors, one has to use a combination of the following modalities:
Surgery
Management of this disease relies on surgery, attempting to remove most or all of the tumor. Surgery on the limb cancers has to be performed by an experienced surgeon who deals primarily with this kind of cancer. Attempts are made to preserve the functionality of the limb. Certain patients can benefit from removal of tumor metastasis from the lungs, especially when the primary site of cancer is managed aggressively and is under control.
Chemotherapy
Chemotherapy is appropriate for patients in whom the disease cannot be cured with surgery. Adriamycin, Ifosphamide, high dose Methotrexate, Cytoxan, DTIC, VP-16, Cisplatinum are among the most commonly used drugs. These drugs are used in combination and can have moderate to severe toxic effects.
More recently, Chemotherapy is used as Neo-Adjuvant treatment with some success. The goal is to shrink the tumor prior to surgery and increase the chance for cure. This approach at times uses concomitant Radiation therapy as well.
Radiation
Radiation, for the most part, is used in combination with surgery and chemotherapy. Radiation at the time of surgery, referred to as Intraoperative radiation, has not proven to be more effective than external radiation.
Pattern of Spread
If left untreated, or if it fails to respond to treatment, these cancers can spread to the Liver, lymph glands in the abdomen, lungs, bones, and almost anywhere else.
Prognosis
These cancers carry a poor prognosis. This is due to advanced stage of the illness at the time of diagnosis. In such cases, survival may be short. The disease can be cured if caught very early and completely resected.
