SOFT TISSUE SARCOMAS (MALIGNANT SOFT TISSUE TUMOURS)

Soft tissue sarcomas are much less common than benign soft tissue tumors. The incidence of malignant soft tissue tumors has been reported to be 15-35 per million and they account for 1-2% of all cancers.

Soft tissue sarcomas can arise from a variety of tissues, including fat, muscle (smooth or striated), fibrous tissue, bone, nerves, and blood vessels. There are many different types. The most common types are: undifferentiated pleomorphic sarcoma, liposarcoma, leiomyosarcoma, fibrosarcoma, rhabdomyosarcoma, snovial sarcoma, malignant peripheral nerve sheath tumor, and celar cell sarcoma. Although it can occur in any part of the body, it is most commonly seen in the extremities (often in the thigh of the lower extremity).

Although soft tissue sarcomas can be seen at different ages, they most commonly occur after the age of 40 and are slightly more common in men. However, rhabdomyosarcoma is more common in children under the age of 10, snovial sarcoma in young adults, and undifferentiated pleomorphic sarcoma in the elderly.

Symptoms

Patients with soft tissue sarcoma usually seek medical attention because of a recent rapid increase in the size of a slowly growing lump.

The fact that the swelling has been present for many years and has not changed in size does not necessarily mean that it is benign. Pain in the area of the swelling is rarely present (snovial sarcoma, malignant nerve sheath tumor, etc.). The absence of pain may lead to the assumption that the tumor is benign and delay the diagnosis. Very large masses may cause vascular and nerve compression and may present with neurovascular findings (numbness, burning, weakness, etc.). Malignant soft tissue tumors are usually deeply localized and large in size, but being superficial and small does not necessarily mean that it is benign.

Diagnosis

Radiologic evaluation of patients with soft tissue sarcomas should begin with direct radiography (x-ray). The most commonly used imaging modality for soft tissue malignancies is contrast-enhanced magnetic resonance imaging (MRI). MRI provides information about size, borders, internal structure, proximity to major vessels and nerves, and surrounding edema. MRI is also used to evaluate response to adjuvant treatment (chemotherapy, radiation), plan surgery, and monitor recurrence after surgery.

Patients with soft tissue sarcoma are diagnosed with a biopsy after clinical and radiologic evaluation. The biopsy is often performed closed or rarely open with specialized needles. Because there are many different subtypes of malignant soft tissue tumors, it is important that the orthopedic surgeon performing the biopsy and the pathologist interpreting the biopsy have experience with bone and soft tissue tumors. The patient diagnosed with a malignant soft tissue tumor will be staged (examined) for the presence of metastasis (spread). PET-CT, CT scan and whole body MRI can be used for screening. These tumors usually metastasize via the hematogenous (blood) route, but some (synovial sacroma, epithelioid sarcoma, clear cell sarcoma, rhabdomyosarcoma, and angiosarcoma) metastasize via the lymphogenous (lymph) route. The most common site of metastasis is the lung.

Treatment

The primary treatment for soft tissue sarcomas is surgical removal of the tumor with wide margins. The tumor that is not cleanly removed with wide margins has a nearly one hundred percent recurrence rate and is prone to metastasis. For this reason, it is critical that the surgeon performing the surgery be an orthopedic oncologist with experience in this area.

Radiotherapy (radiation therapy) is used before or after surgery to facilitate surgery, to contain the tumor from adjacent vascular nerves, and to reduce recurrence. Although there are advantages and disadvantages to using radiation before or after surgery, there is no absolute superiority of one over the other. The most common side effect of radiotherapy is the risk of developing wound problems (infection, wound dehiscence, skin stiffness, etc.). Chemotherapy is not routinely used in the treatment of malignant soft tissue tumors. Chemotherapy is used especially in the presence of metastases, certain subtypes (rhabdomyosarcoma, synovial sarcoma, etc.), deep-seated and large tumors. Patients treated for malignant soft tissue tumors should be followed for many years at regular intervals for recurrence and metastases.