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Today's VeTerinary PracTice | January/February 2016 | tvpjournal.com elemenTs oF oncology Peer reviewed 58 Palliative Chemotherapy chemotherapy is frequently used with palliative intent in veterinary patients. long-term successful outcomes are still possible when chemotherapy is administered with palliative intent, but a reduction in tumor volume or improvement in overall survival time may not be the ultimate goal. Indications Palliative-intent chemotherapy is intended to maximize quality of life by decreasing tumor burden or preventing tumor growth that would impair local function. even in the face of incurable disease, chemotherapy can: • decrease tumor burden, as is often the case with nonresectable or metastatic high-grade mast cell tumors and histiocytic sarcoma • reduce the rate of tumor growth, ultimately preventing potentially life-threatening tumor sequelae, as is often the case with transitional cell carcinoma. Therapeutic Approach noncytotoxic drugs, such as pamidronate and other bisphosphonates, may be useful in palliating bone pain or reducing risk for pathologic fractures associated with osteolysis. These drugs are frequently combined with chemotherapy, radiation therapy, or both in the treatment of canine appendicular osteosarcoma. 33 IN SUMMARY cancer is a complex disease process that requires multimodal treatment, including surgery, radiation, chemotherapy, analgesics, and other nonpharmaceutical therapies. Pain can result not only from the cancer itself but also from the modalities that are employed to treat the cancer. Therefore, multimodal treatment should be used to manage cancer-related pain. as the demand for, and availability of, veterinary cancer care services increase, veterinary practitioners are likely to encounter many of the clinical scenarios outlined in this article. Veterinarians are also likely to encounter pet owners who are interested in pursuing therapy for pets diagnosed with cancer, which requires an understanding of what treatment options are available, when palliative versus defnitive care is indicated, and how to manage pain caused by cancer or its treatment. An 11-year-old, castrated male mixed-breed dog presented for evaluation of changes in mentation, anorexia, and mucohemorrhagic nasal discharge that had been occurring for the previous 3 months. on physical examination, the patient was noted to be circling, and manipulation of the head and nose elicited aggression. The patient had a pain score of 5/5 on the in-clinic scale (See table 3, part 1: pathophysiology & Assessment of Cancer pain, May/June 2015, available at tvpjournal.com). Diagnostic approach Computed tomography (CT) revealed a heterogeneous, contrast-enhancing mass in the nasal cavity, with destruction of the bones of the medial orbit. The mass invaded the cribriform plate and extended caudally for several centimeters into the forebrain, causing meningeal enhancement and lateral shifting of the falx cerebri ( f igure 8). A biopsy of the mass was performed, and squamous cell carcinoma was diagnosed on histopathology. therapeutic approach 1. palliative radiation therapy (4 weekly treatments with an 8-Gy fraction size) was prescribed, using iMRT to spare the eyes and brain. 2. The patient also started receiving prednisone (0.5 mg/kg PO Q 24 H), OTM buprenorphine (120 mcg/kg Q 24 H), and gabapentin (10 mg/ kg PO Q 12 H). When the patient returned 1 week later for the second dose of radiation therapy, the circling behavior had resolved and pain was no longer elicited when the face and head were touched. oTM buprenorphine was discontinued, and the patient was continued on gabapentin and prednisone for the duration of treatment. o utcome The patient was euthanized 3 months after fnishing treatment due to acute progression of neurologic signs and seizures. Consider This Case: Palliative Radiation for Squamous Cell Carcinoma Figure 8. CT scans of a patient with nasal squamous cell carcinoma; note the extensive bony destruction and forebrain invasion. Axial postcontrast CT scan at the level of the cribriform plate and orbit; note the extensive lysis of the medial orbit (*) and lysis of the nasal turbinates (+) (A). Sagittal reconstruction; note the focal contrast enhancement in the forebrain (arrows), destruction of the cribriform plate ( ^), and invasion into the frontal sinus (#) (B). C o A B