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Today's VeTerinary PracTice | January/February 2016 | tvpjournal.com elemenTs oF oncology Peer reviewed 48 • The goal in definitive treatment is long-term control of the cancer and potentially long- term, pain-free survival; iatrogenic pain is to be expected as a consequence of definitive treatment. • The goal in palliative treatment is to relieve cancer pain and slow, or minimize, the rate of cancer progression. Table 1 (page 52) lists pain medications discussed in this article, including dosing and frequency of administration. ACUTE/IATROGENIC CANCER PAIN DUE TO DEFINITIVE TREATMENT as noted, iatrogenic pain induced by defnitive- intent treatments is to be expected. However, the cost of iatrogenic pain in these patients is outweighed by the beneft of longer-term survival. The pain management plan varies depending on the treatment modality used. Defnitive Surgery s urgery is often used to treat localized cancer, and employed with defnitive intent in a number of clinical scenarios, including: • removal of tumors, such as low- to intermediate-grade soft tissue sarcomas or mast cell tumors in which there is adequate room to remove a wide and deep margin (2 cm lateral + 1 fascial plane) • amputation of a limb to remove the anatomic compartment encompassing the tumor (radical surgery). 2-4 Pre- and intraoperative pain control for these types of surgeries is similar to pain management used for orthopedic and soft tissue surgeries (eg, fracture repair, amputation due to traumatic injury). For example, the following medications are often administered: • opioids and maropitant for anesthetic premedication • opioids (with or without ketamine), lidocaine, and dexmedetomidine as intraoperative constant- rate infusions (cris) • opioids or local anesthetics for regional anesthesia techniques, such as nerve blocks. Postoperative pain management is also similar, and frequently involves use of nonsteroidal anti-infammatory drugs (nsaids) and other analgesics, such as opioids. acute surgical pain management techniques have been reviewed extensively elsewhere and are not reviewed in detail here. However, see Consider This Case: Surgical Treatment of Osteosarcoma (page 50) for a case presentation that demonstrates the use of defnitive surgery to treat osteosarcoma. Defnitive Radiation defnitive-intent radiation therapy for residual local neoplastic disease is becoming increasingly common in veterinary medicine. This type of radiation therapy is: • Frequently indicated for treatment of microscopic cancer left behind following first- attempt surgical excision of tumors, including soft tissue sarcomas and mast cell tumors • distinguished by the large size of the total dose delivered and the small size of the dose given at each treatment session (called a fraction). Treatment is typically delivered monday through Friday, with breaks on the weekend, for a total of Use of nerve Blocks In humans, cancer pain management frequently includes nerve blocks, in which analgesic is injected into or around a nerve or into the spinal cord to block pain; nerves may also be transected surgically to relieve cancer pain. 1 These modalities have not been used routinely in veterinary patients but may be worth exploring when other options are limited. For more information on nerve blocks in dogs and cat, read Surgical Skills: local anesthesia for the Distal extremity (September/October 2014), available at tvpjournal.com. U s e o Recent studies have called into question the analgesic effectiveness of tramadol in dogs. 5 Tramadol's analgesic effect for acute/ traumatic pain may be minimal due to lack of metabolic activation of the metabolite (M1) that is needed for mu agonism. In addition, the nonopioid mechanisms of tramadol, including inhibition of serotonin and norepinephrine reuptake, may or may not exist in dogs and cats. Clinically, many cancer patients are geriatric and have comorbidities, such as renal disease, that preclude use of NSAIDs for mild to moderate pain. Therefore, options for at-home pain management are limited. Despite its shortcomings and questions about effcacy, tramadol is widely used due to its convenience, safety, and perceived long duration of action. tramadol: e ffectiveness as a Pain Medication & administration in Cancer Patients