Soft Tissue Sarcoma.
Soft tissue sarcomas (STS) consist of a variety of tumours that arise from mesenchymal cells, (e.g. fat, smooth muscle, blood vessels, lymph vessels, skeletal muscle, etc.), and can be either benign (noncancerous) or malignant (cancerous). Soft tissue sarcomas can arise in any part of the body although skin and subcutaneous tumours (the layer of tissue directly underlying the skin) are the most commonly observed. Tumours included in this group are fibrosarcomas, peripheral nerve sheath tumours, and hemangiopericytomas. They usually are slow-growing, but may also come up quite quickly. These tumours are locally invasive, but they are usually not likely to go to other sites (metastasize).
Soft tissue sarcomas compromise around 15 percent of all skin tumours in dogs. They can be found on all shapes and sizes of dogs, with both pedigree and mixed breed dogs being affected in equal measure. They are not considered to be hereditary cancers, although they are seen more commonly in medium to large dogs, with some studies suggesting slightly more bitches being affected. The terms spindle-cell tumours and mesenchymal tumours have also been used to describe these growths. STS are considered to be a single family of tumours because they are all derived from connective tissues and all have a similar biologic behaviour regardless of the type.
Diagnosis involves either cytological (fine needle aspirate) or histopathological (biopsy) evaluation. If your dog is diagnosed with a STS, the primary treatment recommendation is complete surgical removal of the mass. The feasibility of surgery will depend on the size and the location of the tumour. Because these tumours can be very invasive, diagnostic imaging such as a CT scan can be used to help to identify the extent of the mass prior to surgery.
These tumours present as solitary masses in the subcutaneous tissues and can occur anywhere on the body. They are locally invasive tumours that will grow along tissue planes, often infiltrating deep into surrounding flesh. Invasion into bone is uncommon. The potential for metastasis depends on the grade of the tumour with low to intermediate grade tumours having a metastatic rate of less than 15% and high-grade tumours having a metastatic rate of up to 45% (Kuntz 1997, Selting 2005). The most common site of metastasis is the lung followed by lymph node. Most dogs affected are older to middle-aged with no breed predilection.
Because these soft tissue sarcomas deeply invade adjacent tissues, the most commonly recommended treatment is aggressive initial surgery to remove the tumour along with wide margins of healthy tissue, (3 to 5 cm margins are commonly referred to), to prevent local tumour recurrence.
The prognosis for soft tissue sarcoma is good provided clear margins are removed along with the cancer itself. Local control of the tumour can be very challenging if sufficient clear margins of healthy tissue have not been achieved, and local tumour recurrence rates after surgery (with or without radiation) range from 7% to 32%. Poor prognostic factors for recurrence include large tumour size, incomplete surgical removal and high histologic tumour grade (high grade corresponds with aggressive tumour behaviour). Management of returning soft tissue sarcomas is usually more difficult than surgically removing the original tumour, emphasizing the need for an aggressive excision of the initial tumour.
Soft tissue sarcomas that are low to intermediate grade and can be removed completely with aggressive surgery have an excellent long term prognosis. Some studies indicate a median survival rate of 5 years, with many individuals dying of age-related illnesses rather than due to a recurrence of the cancer.
Survival rates for low grade soft tissue sarcomas that are excised with less than adequate margins and followed by radiation therapy are also very good. Approximately 85% of these patients are tumour free three years after treatment.
By comparison, the majority of dogs with incompletely excised soft tissue sarcomas that receive surgery without follow-up radiation therapy will have their tumours regrow by 1 year after surgery. Many of these tumours often regrow within the first few months after surgery.
For more information on this form of cancer, take a look at this comprehensive website from the West Los Angeles Animal Hospital here.
Soft tissue sarcomas (STS) consist of a variety of tumours that arise from mesenchymal cells, (e.g. fat, smooth muscle, blood vessels, lymph vessels, skeletal muscle, etc.), and can be either benign (noncancerous) or malignant (cancerous). Soft tissue sarcomas can arise in any part of the body although skin and subcutaneous tumours (the layer of tissue directly underlying the skin) are the most commonly observed. Tumours included in this group are fibrosarcomas, peripheral nerve sheath tumours, and hemangiopericytomas. They usually are slow-growing, but may also come up quite quickly. These tumours are locally invasive, but they are usually not likely to go to other sites (metastasize).
Soft tissue sarcomas compromise around 15 percent of all skin tumours in dogs. They can be found on all shapes and sizes of dogs, with both pedigree and mixed breed dogs being affected in equal measure. They are not considered to be hereditary cancers, although they are seen more commonly in medium to large dogs, with some studies suggesting slightly more bitches being affected. The terms spindle-cell tumours and mesenchymal tumours have also been used to describe these growths. STS are considered to be a single family of tumours because they are all derived from connective tissues and all have a similar biologic behaviour regardless of the type.
Diagnosis involves either cytological (fine needle aspirate) or histopathological (biopsy) evaluation. If your dog is diagnosed with a STS, the primary treatment recommendation is complete surgical removal of the mass. The feasibility of surgery will depend on the size and the location of the tumour. Because these tumours can be very invasive, diagnostic imaging such as a CT scan can be used to help to identify the extent of the mass prior to surgery.
These tumours present as solitary masses in the subcutaneous tissues and can occur anywhere on the body. They are locally invasive tumours that will grow along tissue planes, often infiltrating deep into surrounding flesh. Invasion into bone is uncommon. The potential for metastasis depends on the grade of the tumour with low to intermediate grade tumours having a metastatic rate of less than 15% and high-grade tumours having a metastatic rate of up to 45% (Kuntz 1997, Selting 2005). The most common site of metastasis is the lung followed by lymph node. Most dogs affected are older to middle-aged with no breed predilection.
Because these soft tissue sarcomas deeply invade adjacent tissues, the most commonly recommended treatment is aggressive initial surgery to remove the tumour along with wide margins of healthy tissue, (3 to 5 cm margins are commonly referred to), to prevent local tumour recurrence.
The prognosis for soft tissue sarcoma is good provided clear margins are removed along with the cancer itself. Local control of the tumour can be very challenging if sufficient clear margins of healthy tissue have not been achieved, and local tumour recurrence rates after surgery (with or without radiation) range from 7% to 32%. Poor prognostic factors for recurrence include large tumour size, incomplete surgical removal and high histologic tumour grade (high grade corresponds with aggressive tumour behaviour). Management of returning soft tissue sarcomas is usually more difficult than surgically removing the original tumour, emphasizing the need for an aggressive excision of the initial tumour.
Soft tissue sarcomas that are low to intermediate grade and can be removed completely with aggressive surgery have an excellent long term prognosis. Some studies indicate a median survival rate of 5 years, with many individuals dying of age-related illnesses rather than due to a recurrence of the cancer.
Survival rates for low grade soft tissue sarcomas that are excised with less than adequate margins and followed by radiation therapy are also very good. Approximately 85% of these patients are tumour free three years after treatment.
By comparison, the majority of dogs with incompletely excised soft tissue sarcomas that receive surgery without follow-up radiation therapy will have their tumours regrow by 1 year after surgery. Many of these tumours often regrow within the first few months after surgery.
For more information on this form of cancer, take a look at this comprehensive website from the West Los Angeles Animal Hospital here.
