In this context, the term soft tissue refers to tissues that connect, support, or surround other structures and organs of the body. Soft tissue includes muscles, tendons (bands of fiber that connect muscles to bones), fibrous tissues, fat, blood vessels, nerves, and synovial tissues (tissues around joints).

There are many different kinds of soft tissue sarcomas. They are grouped together because they share certain microscopic characteristics, produce similar symptoms, and are generally treated in similar ways. (Bone tumors, also known as osteosarcomas, are also called sarcomas, but are in a separate category because they have different clinical and microscopic characteristics and are treated differently.)

Sarcomas can invade surrounding tissue and can metastasize (spread) to other organs of the body, forming secondary tumors. The cells of secondary tumors are similar to those of the primary (original) cancer. Secondary tumors are referred to as "metastatic soft tissue sarcoma" because they are part of the same cancer and are not a new disease.

Some tumors of the soft tissue are benign (noncancerous). These tumors do not spread and are rarely life-threatening. However, benign tumors can crowd nearby organs and cause symptoms or interfere with normal body functions.

What are the possible causes of soft tissue sarcomas?

Scientists do not fully understand why some people develop sarcomas while the vast majority do not. However, by identifying common characteristics in groups with unusually high occurrence rates, researchers have been able to single out some factors that may play a role in causing soft tissue sarcomas.

Studies suggest that workers who are exposed to phenoxyacetic acid in herbicides and chlorophenols in wood preservatives may have an increased risk of developing soft tissue sarcomas. An unusual percentage of patients with a rare blood vessel tumor, angiosarcoma of the liver, have been exposed to vinyl chloride in their work. This substance is used in the manufacture of certain plastics.

In the early 1900s, when scientists were just discovering the potential uses of radiation to treat disease, little was known about safe dosage levels and precise methods of delivery. At that time, radiation was used to treat a variety of noncancerous medical problems, including enlargement of the tonsils, adenoids, and thymus gland. Later, researchers found that high doses of radiation caused soft tissue sarcomas in some patients. Because of this risk, radiation treatment for cancer is now planned to ensure that the maximum dosage of radiation is delivered to diseased tissue while surrounding healthy tissue is protected as much as possible.

Researchers believe that a retrovirus plays an indirect role in the development of Kaposi's sarcoma, a rare cancer of the cells that line blood vessels in the skin and mucus membranes. Kaposi's sarcoma often occurs in patients with AIDS (acquired immune deficiency syndrome). AIDS-related Kaposi's sarcoma, however, has different characteristics and is treated differently than typical soft tissue sarcomas.

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Improving the management of soft tissue sarcoma - Editorial
From British Medical Journal, 7/11/98 by Anders Rydholm

Diagnosis and treatment should be given in specialist centres

"Musculoskeletal sarcomas comprise 1% of all malignancies and have traditionally been associated with a poor prognosis. However, the past two decades have shown a dramatic improvement in prognosis for osteosarcoma and Ewing's sarcoma when treated by teams of pathologists, radiologists, oncologists, and surgeons who can provide the necessary combination of chemotherapy, surgery, and radiotherapy. A similar evolution has also occurred in some places in the treatment of soft tissue sarcoma. However, whereas no one questions that patients with bone sarcomas should be treated at specialist tumour centres, many patients with soft tissue sarcoma (which is at least twice as common) are treated outside such centres, often with a poor outcome.

Last December Clasby et al reported recent treatment outcomes for soft tissue sarcoma in the South East Thames region of England.[1] The first surgical procedure was a marginal excision (shelling out) in two thirds of cases. Less than half of these patients were given radiotherapy or had a re-excision with wider margins. This means that almost half of the patients had inadequate treatment. Consequently, the local recurrence rate was high and, with longer follow up, recurrence will probably occur in at least a third of the patients. This poor treatment is not unique: most reports from specialist centres all over the world include a substantial proportion of patients first referred after local recurrence because of earlier inappropriate treatment.[2-4] How many patients who are not referred at all is not known. In a Swedish study the local recurrence rate was three times higher in patients treated outside a tumour centre.[5] Local recurrence may be detrimental to the patient and is expensive. In a recent Scandinavian investigation the median cost of operation for local recurrence was 7000 [pounds sterling] (USS 11 000) and a fifth of the patients needed an amputation (C Trovik, personal communication).

Soft tissue sarcomas are commoner with increasing age but do occur in younger people. Two thirds of the tumours are situated in the extremities and often present as a lump incidentally noticed by a patient in good general health with no pain or loss of function despite a tumour that may be large: the median size of deep seated extremity sarcomas is 9 cm.[6] This presentation makes soft tissue sarcomas easy to misdiagnose as benign tumours, such as lipomas, or muscle ruptures. Optimal treatment requires preoperative staging, including magnetic resonance imaging of the tumour, chest radiographs, and biopsy (incisional or needle). For a correct diagnosis of the over 50 histological types of soft tissue sarcoma conventional light microscopy often has to be supplemented by immunohistochemistry, electron microscopy, DNA cytometry, and cytogenetics or molecular genetics.

Limb sparing procedures--often with the help of plastic surgery--can be performed in nine tenths of patients and are often combined with radiotherapy. This treatment requires referral before surgery: anatomical staging is impossible after shelling out, and the risk of local recurrence is high even after re-excision with a wider margin.[7] Also open biopsy before referral is dangerous: outside a specialist centre wrong diagnoses are common because of inexperienced surgeons (who do not sample representative tissue) or pathologists (who do not seek second opinions),[8] Patients managed in specialist centres are regularly followed for early detection of recurrence, either local (in 10-15% of patients) or distant (in more than a third, the commonest being pulmonary metastases). Chemotherapy and metastatectomy are increasingly used. With this treatment programme, morbidity and mortality from soft tissue sarcoma have decreased substantially.

How can we ensure that more patients get the benefit of optimal treatment? Twenty five years ago we faced the same problem as Clasby et al and started a sarcoma centre in the southern region of Sweden. We soon realised that the mere existence of a centre was not sufficient: during the first five years of our tumour service data from the Swedish national cancer registry showed that only a third of patients with soft tissue sarcoma were referred before surgery and a third were not referred at all. Most of the patients referred before surgery had been seen by orthopaedic surgeons, whereas general surgeons usually shelled out all lumps for diagnosis--Clasby et al found the same. We lacked clearcut guidelines on which tumours to select for referral from among the overwhelming numbers of benign lesions that were 200 times more common.

Based on epidemiological data we formulated the following simple guidelines: refer to our centre before surgery all patients with soft tissue lesions that are (a) larger than 5 cm or (b) deep seated (muscular) or (c) otherwise suspected of malignancy. We repeatedly lectured at local hospitals explaining the advantage of following these guidelines. We gave the same information to all medical students during their course in pathology and again during general surgery and orthopaedics. Doctors who referred patients with sarcoma before surgery were sent personal letters outlining the specific advantages for their patients. The outcome was remarkable: over the past 10 years over four fifths of all patients in our region with a deep seated soft tissue sarcoma of the extremity or trunk wall have been referred before surgery? This experience exemplifies one strategy for achieving the necessary centralisation of soft tissue sarcoma.

[1] Clasby R, Tilling K, Smith MA, Fletcher CDM. Variable management of soft tissue sarcoma: regional audit with implications for specialist care. Br J Surg 1997; 84:1692-6.

[2] Singer S, Corson JM, Gonin R, Lbow B, Eberlein TJ. Prognostic factors predictive of survival and local recurrence for extremity soft tissue sarcoma. Ann Surg 1994;219:165-73.

[3] Pisters PWT, Leung DHY, Woodruff J, Shi W, Brennan ME Analysis of prognostic factors in 1041 patients with localized soft tissue sarcomas of the extremities. J Clin Oncol 1996; 14:1679-89.

[4] Ueda T, Yoshikawa H, Mori S, Araki N, Myoui A, Kuratsu A, et al. J Bone J Surg Br 1997;79:553-7.

[5] Gustafson P, Dreinhofer KE, Rydholm A. Soft tissue sarcoma should be treated at a tumor center. A comparison of quality of surgery in 375 patients. Acta Orthop Scand 1994;65:47-50.

[6] Gustafson P. Soft tissue sarcoma. Epidemiology and prognosis in 508 patients. Acta Orthop Scand 1994;259 (suppl):1-31.

[7] Davis AM, Kandel RA, Wunder JS, Unger R, Meer J, O'Sullivan B, et al. The impact of residual disease on local recurrence in patients treated by initial unplanned resection for soft tissue sarcoma of the extremity. J Surg Oncol 1997;66:81-7.

[8] Mankin HJ, Mankin CJ, Simon MA. The hazards of the biopsy, revisited. Members of musculoskeletal tumor society. J Bone Joint Surg Am 1996;78:656-63.

[9] Rydholm A. Centralization of soft tissue sarcoma. The southern Sweden experience. Acta Orthop Scand 1997;273(suppl):4-8.

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