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Treatment Options For A Dog With Myxofibrosarcoma

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Lili Duda, VMD
Last Modified: November 1, 2001

Dear OncoLink "Ask the Experts,"
Our dog has been diagnosed with myxofibrosarcoma. Given the tumor's size, location and aggressiveness, and the consequent difficulty of securing a tumor-free margin without extensive penetration into the chest, we are considering palliative care options. This is where the questions arise:

1. The tumor is pushing out against the skin along his ribs, and we're concerned about ulceration. Is repeated aspiration of the fluids in this type of lump a reasonable and safe method to avoid the problem, especially over many months?
2. Apart from the tumor itself, is the necrosis and minor bleeding described by our doctor causes for concern? That is, is there any likelihood that these conditions could create problems of their own; in the intervening time before the tumor runs its course? If so, is there anything we can do to improve the situation?

Lili Duda, VMD, Editor of the OncoLink Veterinary Oncology Section, responds:

Superficial ulceration of large tumors is a frequent complication. It is unlikely that fluid-filled pockets within a tumor are much of a contributing cause of surface ulceration, and aspiration is not likely to be very helpful. However, in the few cases where a tumor does contain a solitary, large fluid-filled center, aspiration might be helpful to relieve the pressure. Ultrasound is recommended to confirm the presence of a fluid-filled area prior to aspiration. The procedure should be performed using sterile conditions in order to minimize the risk of infection. Another palliative treatment option that might provide temporary relief is radiation therapy. Chemotherapy might also provide short-term palliation in some cases.

For locally invasive tumors that either do not metastasize or metastasize late in the progression of the cancer, tumor associated problems are generally localized problems. The presence of necrosis, ulceration and bleeding are part of the cancer "running its course", and it is these types of complications that often result in a decision for euthanasia. Systemic problems are unlikely to occur unless the localized infection and inflammation at the tumor site become so severe that the problems become systemic. Even if metastasis does occur, it is often asymptomatic—it is the primary tumor that causes the majority of the symptoms in most cases.

For most purposes, low-grade soft tissue sarcomas have a similar clinical course. Some tumors do tend to be firmer and more solid, and some tend to be softer and more fluid. In addition, many tumors, and in particular rapidly growing tumors may have a central area of dead, liquefied tumor cells. However, the particular type of sarcoma (fibrosarcoma vs. myxosarcoma for example) does not make a difference in case management or outcome.