"Medical Management of Insulinoma - Part 2" TUMOR TIDBITS, A BIWEEKLY EMAIL NEWSLETTER FROM GULF COAST VETERINARY ONCOLOGY Number 102; July 4, 2003. ======================================================================= THIS WEEK'S TUMOR TIDBIT: MEDICAL MANAGEMENT OF INSULINOMA ======================================================================= Free Cancer Therapy for 4 months! Dogs without lymphoma having a hematocrit between 19% and 37% and a creatinine <1.8 may be eligible for this anemia study. The qualification examination is provided at no cost and eligible dogs may have all services provided at no charge (including any appropriate surgery, radiation, or chemotherapy) for 4 months. Call our offices in Houston (713.693.1166, Ms. Kelly Griffice) or San Antonio (210.822.1913, Ms. Waynette Wheeler) for additional information. Want a copy of our latest Oncology Handbook? A download is available at: http://www.gcvs.com/oncology/download.htm ======================================================================= MEDICAL MANAGEMENT OF INSULINOMA In part two of this Tidbit on Insulinomas, a brief (hence tidbit) review of the medications used in the acute and long-term management of dogs with a diagnosis of insulinoma is provided. Acute management of a dog that presents in a hypoglycemic seizure or coma can be initiated with 2-10ml of 25% dextrose given over 10 minutes IV. Once alert or sternal, the dog should be fed. Prior to any therapy, try to obtain enough blood to be able to confirm your diagnosis. Chronic management of a patient with an insulinoma includes a variety of recommendations and options. Diet plays an important role in these dogs; feed frequent small meals high in fat, protein, and complex carbohydrates. Avoid simple sugars which may lead to increased insulin release and post-prandial hypoglycemia. Exercise should be limited, bearing in mind that quality of life is critical and some dogs will not tolerate low activity levels well. Drug therapy includes treatments to raise blood glucose levels as well as chemotherapy to target the malignant cells. Glucocorticoids antagonize insulin at the cellular level, leading to decreased cell uptake and increased blood glucose, stimulate hepatic gluconeogenesis, and indirectly provide substrates for glycogenolysis. Prednisone at 0.5mg/kg/day divided into 2 to 3 doses may actually resolve the hypoglycemia or at least resolve the clinical signs. The dose will become ineffective over time and may gradually be increased up to 4-6 mg/kg/day as needed to control clinical signs of hypoglycemia. If no benefit is seen, other treatments are needed. Diazoxide, a benzothiadiazide diuretic, works via inhibition of insulin secretion, stimulation of gluconeogenesis and glycogenolysis, inhibition of cellular glucose uptake, and stimulation of epinephrine release. The dose is 5 mg/kg twice daily, and you may gradually increase the dosage but do not exceed 60mg/kg/day. Side effects seen are mainly anorexia and vomiting, which may be prevented by giving the treatment with a meal. Little data is available on the effectiveness of this therapy. It has been reported to be of benefit in a small number of dogs. Unfortunately, this medication is very expensive. Streptozotocin, a nitrosourea chemotherapeutic that is specifically toxic to beta cells, is being evaluated by a number of oncologists. Thought unsafe to give due to nephrotoxicity until recently, streptozotocin can be safely given with aggressive saline diuresis. The drug is also extremely emetogenic -pretreatment with butorphenol is required. In a recent paper, 2/17 dogs treated with streptozotocin developed diabetes mellitus, a potentially serious complication as some dogs with insulinomas may survive for years postoperatively. Compared to a historical control group, the treated dogs did not have a significantly longer period of normoglycemia. Thus, the effectiveness of this therapy has yet to be proven. Cases managed surgically (+/- medical therapy post-op) generally survive longer than with medical therapy alone. Debulking metastatic disease will increase survival times. The median survival with surgery in 26 dogs was 381 days vs. 70 days in 13 dogs treated with medical therapy alone. In another study, 31 dogs with resectable tumor/metastases had a median survival of 258 days. Dogs in that study that were hyperglycemic or normoglycemic post-op had a median survival of 680 days vs. 90 days if they were hypoglycemic. In a third study, dogs that were normoglycemic post-op (18) survived > 435 days. Eleven dogs that were hypoglycemic post-op and treated medically survived a median of 215 days (with one dog alive > 704 days). In summary, stage of tumor and post-operative glucose levels can be used to predict survival times, but there is a range of survivals and some individuals can live 2-3 years with treatment. ======================================================================= As always, we hope this info helps and don't hesitate to call or email us Gulf Coast Veterinary Oncology! Kevin A. Hahn, DVM, PhD, Diplomate ACVIM (Oncology), drhahn@gcvs.com Janet K. Carreras, VMD, Diplomate ACVIM (Oncology), drcarreras@gcvs.com Glen K. King, DVM, MS, Diplomate ACVR (Radiology & Radiation Therapy), drking@gcvs.com Gulf Coast Veterinary Diagnostic Imaging & Oncology 1111 West Loop South, Suite 150, Houston, TX 77027 P: 713.693.1166 F: 713.693.1167 W: www.gcvs.com ======================================================================= Copyright © 2003, Gulf Coast Veterinary Oncology