"Astrocytomas"
TUMOR TIDBITS, A BIWEEKLY VETERINARY ONCOLOGY E-LETTER
Volume 3; Number 3; January 25, 2002.

Editor: Kevin A. Hahn, DVM, PhD, Dipl - ACVIM (Oncology) & Overall Nice Guy!

ANNOUNCEMENTS

1 - Come Celebrate!  We're having a Celebration of Life reception Saturday March 23rd at 
Gulf Coast Veterinary Oncology.  Bring a picture of your pet to place in our new display 
case.  Sorry, no pets allowed since we will be celebrating in our Deli.  

2 - Free chemotherapy for lymphoma!  Beginning April 15th, we will be offering a free 
chemotherapy trial for dogs diagnosed but previously untreated lymphoma. 

Check our web site regulary for details!!!!


THIS WEEK'S TUMOR TIDBIT:  ASTROCYTOMAS

OVERVIEW OF WHAT'S IN THE TEXTBOOKS:

Astrocytoma is a glial cell neoplasm that develops most often within the piriform lobe in 
dogs and the parietal region in cats. Onset of signs is insidious in some animals, who 
may compensate initially to gradual increases in intracranial pressure and peritumoral 
edema. 

SIGNALMENT 
* Dogs--brachycephalic breeds; most dogs 6-11 years old; no sex predilection 
* Cats--generally old (> 9 years); no strong sex or breed predilection 
* Less common in cats than dogs 

SIGNS 
* Signs on examination depend on tumor location 
* Seizures 
* Behavioral changes 
* Disorientation or wandering in wide circling pattern 
* Loss of conscious proprioception, cranial nerve abnormalities, upper motor neuron 
tetraparesis 

DIFFERENTIAL DIAGNOSES 
* Other primary or metastatic neoplasm 
* Granulomatous meningoencephalitis 
* Trauma 
* Cerebrovascular accident 
* Aberrant parasite migration 
* Meningitis 

DIAGNOSTIC TEST RESULTS
* Laboratory results usually normal 
* Consider computerized tomography, magnetic resonance imaging.
* Radiography of the calvarium rarely aids in detecting brain tumor 
* Consider cerebrospinal fluid analysis--normal to mild increase in protein with or 
without WBC pleomorphism 
* Electroencephalography may indicate location of a lesion. 


TREATMENT GOALS
* Symptomatic 
* Control clinical signs 
* Control seizures 
* Chemotherapy indicated 
* Surgery not indicated 
* Excellent tumor remission and control achieved by radiotherapy in some animals 
* Ultimate prognosis is poor 


SEIZURE CONTROL
* Status epilepticus (emergency): 
   * Mannitol--2 g/kg IV with a second dose 12 hours later 
   * Dexamethasone--2.2 mg/kg IV with a second dose 12 hours later 

Long-term Management: 
* Prednisone (0.5 - 1 mg/kg PO q12h) to reduce associated inflammation and edema 
* Phenobarbital (1-4 mg/kg PO q12h) 

Tumor Control 
* Consider Carmustine (50 mg/m2 IV q6wk) 
* Consider Radiation therapy (protocols vary among oncologists)

CONTRAINDICATIONS/POSSIBLE INTERACTIONS 
* Prednisone and phenobarbital cause polyphagia, polydipsia, and polyuria. 
* Sedation for up to 2 weeks after initiation of phenobarbital 

PATIENT MONITORING 
* Modify phenobarbital dosage according to serum concentrations 5-7 days after initiating 
treatment. 
EDose-limiting side effect of carmustine administration is myelosuppression; a CBC and 
platelet count should be performed in 10-14 days 
* Cumulative dose of 1400 mg/m2 can cause pulmonary toxicity. 
* Seek advice before initiating treatment if unfamiliar with cytotoxic drugs. 

EXPECTED COURSE AND PROGNOSIS 
* Guarded prognosis due to seizure complications regardless of tumor size
* Survival time with no treatment reportedly 2 months 
* Median survival time for carmustine plus prednisone, and phenobarbital as needed, 218 days 


WHAT DO WE DO AT GULF COAST?
* Following CT or MRI localization of the tumor, if appropriate, we consider a craniotomy 
and tumor removal.
* Following tumor removal we consider radiation therapy (3 times per week for 7 weeks) to 
a total tumor delivered dose of 62Gy.
* In about 15 dogs to date, with or without craniotomy, the median survival time is 19 
months with a 35% 2 year survival rate.
* Without surgery or radiation, we consider Carmustine (BCNU) or Lomustine (CCNU) 
palliative chemotherapy.


Don't hesitate to call or email us at Gulf Coast Veterinary Oncology!

ALL THE BEST,

Kevin A. Hahn, DVM, PhD
Diplomate ACVIM (Oncology) & Overall Nice Guy
Gulf Coast Veterinary Specialists
1111 West Loop South, Suite 150
Houston, TX 77027
P: 713.693.1166    
F: 713.693.1167
http://www.gcvs.com   
mailto:drhahn@gulfcoastvetspec.com