What are soft tissue sarcomas?

In general terms, soft tissue sarcomas refer to a group of tumours that most often form from the skin and subcutaneous (layer of tissue directly under the skin) tissue. Soft tissue sarcomas are grouped together because they behave in a similar manner. They are named depending on the tumour location:

fat: Liposarcoma
muscle: Rhabdomyosarcoma, Leiomyosarcoma
cartilage: Chondrosarcoma
fibrous connective tissue: Fibrosarcoma
nerves: Schwannoma, Malignant Peripheral Nerve Sheath Tumour, Neurofibrosarcoma)
small blood vessels: Hemangiopericytoma

Soft tissue sarcomas can be benign or malignant and usually affect middle-aged and older dogs, especially larger breeds.

Soft tissue sarcomas are graded as low, intermediate and high. Most tumours are low to intermediate grade and don’t usually spread to other organs. High grade soft tissue sarcomas have a 25 to 40 per cent chance of spreading to other organs such as the lungs, liver, spleen, lymph nodes, kidneys and bone depending on where the tumour originates.

Causes of soft tissue sarcomas

The direct cause of soft tissue sarcomas is unknown.

What are the symptoms of soft tissue sarcomas?

Often, soft tissue sarcomas appear as a firm mass located on the trunk, limbs or in the mouth. The symptoms of soft tissue sarcomas will depend on where the tumour is located and how far the disease has progressed.

For example, if the tumour is located in the gastrointestinal tract, symptoms may include vomiting, diarrhea and/or weight loss. Symptoms of tumours located in the mouth may include bad breath, difficulty swallowing and/or loss of appetite. Tumours that form in the nerves outside of the brain and spinal cord may cause pain, lameness or neurological symptoms such as lack of balance and weakness.

How are soft tissue sarcomas diagnosed?

As with other tumours, soft tissue sarcomas are diagnosed using a fine-needle aspirate and/or a biopsy to confirm the presence of a soft tissue sarcoma and/or to determine its grade. Other tests may include routine blood work, chest x-rays, and abdominal ultrasound to determine how far the disease has progressed and whether the cancer has spread to the surrounding tissue and/or to other organs.

Treatment and prognosis

Surgery is the usual treatment for soft tissue sarcomas. In addition to the tumour, a wide area (margin) around the tumour will need to be removed to ensure removal of all tumour cells. If there is no cancer present in the margins after surgery then no further treatment may be necessary. But, if tumour cells are still present after surgery, then depending on where the tumour is located, a second surgery, radiation therapy and/or chemotherapy may be recommended.

When the tumour cannot be adequately removed or surgery is not an option, radiation therapy can be used to prevent or delay the growth or regrowth of the tumour. Chemotherapy is usually recommended for high grade soft tissue sarcomas to prevent or delay the spread of cancer to other organs.

The prognosis of low to intermediate grade soft tissue sarcomas treated with aggressive surgery and/or radiation therapy is very good — many pets are cancer free from three to five years after treatment. Pets with high grade sarcomas who are treated with surgery and/or chemotherapy will live about a year after treatment.

Unfortunately, some soft tissue sarcomas reoccur on average about a year after surgery. With this in mind, aggressive treatment of the original tumour is advised as are frequent checkups with your vet.

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This page has been reviewed by our Panel of Experts for accuracy. Our Panel of Experts is comprised of practitioners with varying specialties and perspectives. As such, the views expressed here may not be shared by all members of our Panel.

The content on this website is for informational purposes only and is not intended to be a substitute for professional veterinary medical advice, diagnosis or treatment.