"Prognostic Factors in Veterinary Oncology" TUMOR TIDBITS, A BIWEEKLY VETERINARY ONCOLOGY E-LETTER Number 66; August 23, 2002. Editor: Kevin A. Hahn, DVM, PhD, Dipl - ACVIM (Oncology) & Overall Nice Guy! ANNOUNCEMENTS *Did you know that 89% of canine mammary tumors contain estrogen receptors (as published in Pol J Vet Sci 2002;5(1):1-5)? Read below about other useful factors for predicting cancer prognosis! *The Annual Meeting of the Veterinary Cancer Society is coming up soon, check www.vetcancersociety.org for details and notes! *We're revising our web site! Check regularly for updates or call us at any time! ======================================================================= THIS WEEK'S TUMOR TIDBIT: PROGNOSTIC FACTORS IN VETERINARY ONCOLOGY ======================================================================= At the recent AVMA Meeting in Nashville, Dr. Carolyn Henry from the University of Missouri-Columbia did a fantastic job summarizing what we know about determining the prognosis for our pets with common cancers. The information below was obtained from her notes at the meeting and provides a good "Tidbit" that we could all use in our clinic. Canine lymphoma (LSA): Most reports suggest that dogs with Stage I and II disease fare better than those with Stage V. Similarly, those dogs that are clinically ill have a poorer prognosis than those without systemic illness. High to medium grade tumors are associated with a good initial response, but short survival times. T-cell tumors generally warrant a poorer prognosis than B-cell tumors. Cutaneous, alimentary, and bone marrow sites are associated with a poor prognosis, as is male gender, hypercalcemia and previous corticosteroid therapy. Dogs < 15 kg reportedly have a better prognosis than large dogs, likely because dosing chemotherapy drugs on a m2 basis may provide a relatively larger area under the curve (AUC) for the drugs in small dogs. Feline lymphoma: Cats with FeLV have shortened overall survival times compared to aviremic cats. Lower stage disease (I or II) provides a survival advantage over Stage III to V disease. Serum a1-acid glycoprotein (AGP), an acute phase protein, was investigated as a prognostic factor, but did not correlate with response or survival. Likewise, markers including PCNA labeling index and CD3-immunoreactivity (T-cell lymphoma) are apparently not useful in cats with LSA. Clinical illness and poor response to therapy predict poor clinical outcome. Cats that receive doxorubicin in their chemotherapy protocol are more likely to have durable responses. Lung tumors in dogs: The most common canine primary lung tumors are adenocarcinomas (ACA), with squamous cell carcinoma (SCC) reported less commonly. SCC warrants a poorer prognosis, as it tends to be diffuse at the time of diagnosis. Tumor size > 2 inches or 100 cm3, lymph node metastasis, and presence of pleural effusion also warrant a poor prognosis. Of these factors, lymph node involvement is one of the most significant, with a marked survival advantage (12 months vs. 60 days) for dogs with negative nodes. Dogs with peripherally located tumors fare better than those with tumors involving an entire lobe. Canine nasal tumors: Because many studies have included various nasal tumor types, it is difficult to discern true prognostic factors. What seems clear is that metastasis a poor prognostic factor. For ACA, degree of local invasion was of no prognostic value, while presence of metastasis was. Two reports indicated improved survival for dogs with sarcomas vs. carcinomas; ACA reportedly responds better to radiation than SCC or other carcinomas. Canine osteosarcoma: Dogs <5 years of age with OSA reportedly have a poorer prognosis than older dogs. For appendicular OSA, high presurgical total alkaline phosphatase (TALP) and bone-specific alkaline phosphatase (BALP) were associated with shorter disease free interval (DFI) and survival in one study. Failure of BALP to decrease after surgery correlated with shorter DFI and survival time. Another study confirmed the prognostic value of pretreatment ALP, but did not show that post-treatment levels predict survival. Mandibular masses carry a better prognosis than other axial sites. Of appendicular sites, the humerus is associated with poor outcome. Large tumor size and metastatic disease are associated with a poor prognosis. Canine mammary tumors: Approximately 50% of mammary tumors in dogs are malignant. Dogs with high-grade/poorly differentiated tumors have a poor prognosis and those with inflammatory mammary carcinoma or sarcoma rarely survive one year. Small tumor size is a favorable prognostic factor unless lymphatic invasion has occurred. In one study, dogs with tumor invasion into lymphatic or blood vessels had a 97% recurrence or metastatic rate at two years, compared to 19% for tumors limited to the mammary duct system. Nodal metastasis may imply a higher likelihood of tumor recurrence. Peritumoral lymphoid cellular reactivity warrants a better prognosis, likely because it indicates an immune response. Recurrence is almost twice as likely for Grade I tumors lacking this reactivity. Other negative prognostic factors are tumor ulceration, DNA ploidy, S-phase activity, lack of hormone receptor activity, obesity, and young physiologic age. Tumor location, number of tumors, and type of surgery are not prognostic. Feline mammary tumors: Mammary tumors in cats are generally aggressive and highly metastatic. Tumor size is the most significant prognostic factor, as cats with tumors <2-cm diameter have median survival time > 3 years, while those > 3-cm diameter have 4 to 6-month median survival time. Unlike in dogs, radical mastectomy is recommended in cats to reduce the likelihood of local recurrence, but it may not improve survival. Tumor grade is prognostic, as well-differentiated tumors with a low mitotic rate are associated with improved survival. Oral tumors: Prognosis for pets with oral tumors depends upon tumor type. The most common diagnoses are malignant melanoma (MM), SCC, and fibrosarcoma (FSA). Known prognostic factors for oral MM include tumor stage and the success of first surgery in affording local tumor control. Aggressive surgery does not improve survival over a limited, but complete resection. In one report, dogs with Stage I (< 2 cm and no nodal metastasis) MM lived longer than those with larger or metastatic disease. However, a report of maxillary resection for oral tumors showed no significance of clinical stage in 14 dogs with MM. Rostral location is a favorable prognostic factor for canine SCC, while tonsillar or unresectable lingual sites warrant a poor prognosis. Prognostic factors for feline SCC are not established, as the prognosis for all sites and stages appears poor. Prognostic factors for oral FSA are not established. Local control of this tumor is problematic. When all oral tumor types treated with partial maxillary resection were compared, rostral tumor location and tumor-free surgical margins were associated with improved survival. SUGGESTED READING * Proceedings of the American Veterinary Medical Association, 2002, Nashville, TN. * Veterinary Oncology, From "The Practical Veterinarian Series". By Hahn KA. Butterworth-Heinemann Press, 2002. ======================================================================= I hope this info helps and don't hesitate to call or email us at Gulf Coast Veterinary Oncology! Kevin Kevin A. Hahn, DVM, PhD Diplomate American College of Veterinary Internal Medicine (Oncology) & Overall Nice Guy 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 Email: drhahn@gcvs.com