"Surgical Concerns for Insulinoma" TUMOR TIDBITS, A BIWEEKLY EMAIL NEWSLETTER FROM GULF COAST VETERINARY ONCOLOGY Number 101; June 27, 2003. ======================================================================= THIS WEEK'S TUMOR TIDBIT: SURGICAL CONCERNS FOR 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 ======================================================================= SURGICAL CONCERNS FOR INSULINOMA Surgery allows for a definitive diagnosis, prolonged survivals are attained if there is just a solitary nodule, and debulking metastatic disease may improve clinical signs and make medical management easier. Pre-operative treatment: Many dogs with insulinomas will look clinically normal with very low blood glucose levels, and the goal is NOT to get their glucose into the normal range. The goals of pre-operative management are to limit any severe signs of hypoglycemia and to try to prevent post-operative pancreatitis. Small, frequent feedings are helpful, as are glucocorticoids (see medical management) to raise the blood glucose. Fluids are to be administered throughout the evening prior to surgery, both to ensure good pancreatic circulation to help prevent pancreatitis as well as to allow for a continuous infusion of dextrose in a hypoglycemic patient being fasted prior to surgery. Do not use dextrose at > 5% concentration as higher concentrations may over stimulate the pancreatic tumor cells and lead to potentially fatal rebound hypoglycemia. Intraoperative treatment: Pancreatic surgery is a very delicate task and should not be approached lightly. If comfortable with such surgery, the practitioner can be guided by the following information. To begin, the entire pancreas must be examined – both visually and by palpation. Handle the pancreas very gently, but there may be more than one mass, and the mass (or masses) may not be visible. The tumors are approximately evenly divided between the right and left lobes, with only about 10% occurring in the middle lobe. In one study, 3/72 dogs had diffuse islet cell carcinoma throughout the pancreas, identifiable only histologically. If a mass is not found, (which occurred in 20% of 129 cases) intraoperative ultrasound may be of benefit, but has limited availability. The recommendation is to excise 50% of the pancreas, in hopes that the neoplastic tissue will be removed. Send the entire excised portion for histopathology. As critical as removal of the primary tumor is the thorough examination of the entire abdomen for metastasis. Any abnormal tissue should be excised or debulked. Intraoperative cytology can help confirm if a lesion is an insulinoma metastasis or a more benign process. Biopsy any liver nodule or enlarged lymph node if excision is not possible. Lastly, monitor blood glucose regularly (every 30 minutes at least) during surgery. Post-operative complications: Pancreatitis is always a concern post-pancreatic surgery. Try to prevent this complication by presuming it is there postoperatively. Treat the patient with IV fluids, NPO for 24-48 hours and then low-fat food for 1-week post-op. Diabetes mellitus may develop due to atrophy of normal islet cells; these patients may need insulin therapy but only if hyperglycemia and glucosuria last > 2-3 days beyond when dextrose fluids are discontinued. Insulin is usually only needed temporarily. Persistent hypoglycemia is a poor prognostic finding post-op; this indicates functional remaining malignant tissue, and medical treatment is indicated. Post-operative monitoring: In dogs that have all of their tumor removed and are returned to a normoglycemic state, monitor for recurrence over time by checking an 8-hour fasting blood glucose every 1-3 months, if ever less than 70 mg/dl, send serum for an insulin level. Also monitor with abdominal ultrasound every 3 months. Prognosis: 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. The stages are: stage 1 (pancreatic nodule only), stage 2 (regional lymph node metastasis), and stage 3 (distant metastasis, usually liver). In one study of 73 dogs, stage 1 had the longest disease-free interval (no hypoglycemia – median 14 months). Stage 1 and 2 had similar survivals (median of 12-18 months). Stage 3 lived on average 6 months. Some dogs will do very well: 5 patients lived between 24-36 months (2 stage 1, 3 stage 2). Younger dogs lived LESS long than older dogs. 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. ======================================================================= 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