Tumors & Conditions for which a Radiation Therapy Consultation should be considered:

Acanthomatous Epulis Adamantinoma Adenocarcinoma Ameloblastoma Anal Sac Tumors Bone Tumors (Palliation) Brain Tumors Ceruminous Gland Tumors Fibrosarcoma Granular Cell Tumors

Granulomatous Meningoencephali tis Hemangiopericy toma Histiocytoma Lick Granuloma Localized Lymphoma Malignant Fibrous h’istiocytnma Mast Cell Tumors Melanoma Ocular Tumors M yzo sa rcoma

This listing avoids the general terms of radioresistant or radiosensitive as they are no longer considered ad- equate based on histology alone. Further, new tech- niques and modalities continue to be developed which can change the likelihood of control for a particular tumor. Individual tumors and conditions must be evaluated with respect to cell type and grade, stage, location, therapeutic intent and types of treatment (in- cluding concomitant or adjuvant surgery or chemo-

Nasal Cavity Tumors Nerve Sheath Tumors Osteosarcoma Perianal Tumors Pituitary Tumors PI asmac y toma Prostate Tumors Rectal Carcinoma Salivary Gland Tumors Sarcoid Sebaceous Gland Tumors Seminoma

Soft tissue Sarcomas Spinal Cord Tumors Squamous Cell Carci

Sweat Gland Tumors Synovial Cell Tumors Thymoma Thyroid tumors

a Transitional Cell

Transmissible Venereal

noma

Carcinoma

Tumor

therapy) available. Total excision remains the treat- ment of choice if it can be accomplished with accept- able level of risk for morbidity and mortality and if a tumor free zone around the tumor can be established. When this cannot be accomplished, we strongly rec- ommend a radiation therapy consultation for complete evaluation for treatment of the above tumors and con- di tions.

Submitted by Dr. Ronald Burk, Plantation, Florida

Radioiodine Usage At the 1992 meeting of the Society of Veterinary Ra- diation Oncology, interest was expressed in collecting data on dose protocols currently used for treatment of hyperthyroidism in cats. A survey was sent out to each of the institutional practices in the United States and Canada, and to ten private practitioners who were either known to be licensed to use radioactive materi- als or were members of the Society of Veterinary Nu- clear Medicine. Responses were received from 27 practices in time for inclusion in this report. Fourteen institutions indicated they did not currently offer radioiodine therapy, but many indicated that they planned to do so in the fu- ture. Five individuals and eight institutions provided information on their protocols, which is summarized below.

Route of Administration # responses oral capsule 1 IV injection 12

The majority of respondents administer a fixed dose of lnlI to cats with benign hyperplasia, and three adminis- ter a range of doses, as shown in the two charts below

Fixed Dose for Dose Ranges for Benign Disease Benign Disease

2 4 6 8 1 0 Dose in rnCi

a b c Respondent

Of the nine who treat cats suspected or known to have malignant thyroid carcinoma, five give a fixed dose and four give a range of doses:

Fixed Dose for Dose Ranges for Malignant Disease Malignant Disease

10 20 30 40 Dose in mCi

a b c d Respondent

Criteria used to select the dose for Benign Disease, if variable:

4 T4 level 2 previous thyrotoxic drugs 1 thyroid scan findings 1 nodule size 1 patient's condition 1 concurrent diseases

Criteria used to select dose for Malignant Disease: 1 1 thyroid scan findings 1 body weight

tumor mass & whether surgically dcbulked

Many criteria were used to distinguish between be- nign and malignant disease:

7 scan appearance 2 biopsy 4 2 symptons 3 T4 3 chest/long mass on radiographs 1 2 no distinction made

biopsy if scan or history suspicious

failure to respond to low dose 1311

The wide variety of protocols in use suggests the need for further studies to clarify the appropriate radioiodine dose for treatment of feline hyperthyroidism. My thanks to all who participated in this survey.

Submitted by Catherine Lustgarfen, DVM, MS,

Radiation Therapy of Canine Brain Masses From the sections of Radiology (SME), Neurology (BDH) and Pathology (TVW), Veterinary Hospital of the University of Pennsylvania, 3850 Spruce St., Phila- delphia, PA 19104, and the Department of Radiation Oncology (WP, GC), Hospital of the University of Pennsylvania, 3400 Spruce St., Philadephia, PA 19104.

The purpose of this study was to determine the re- sults of the definitive treatment of 14 dogs with brain masses using orthovoltage irradiation. Dogs were anesthetized for CT examination, formation of head immobilization and positioning devices, radiation treatment simulation and treatments. Total tumor doses of 39 Gy (nine dogs) or 45 Gy (five dogs) were administered over 25-41 days. Two or three portals (parallel opposed lateral with or without a dorsal field) were used. Treatment volumes included the tumor and peritumoral edema, as determined by CT scan, and a 1 cm margin. '

Histopathologic diagnoses were available in nine of 14 dogs. There were four meningiomas, one lymphosarcoma, one pituitary adenoma, one metastatic anaplastic carcinoma, one anaplastic oligodendroglioma and one dog with granulomatour meningoencephalitis. At the end of radiation therapy, 10 dogs could be evalu- ated for progression of clinical signs: three dogs dete- riorated or failed to improve and seven dogs im- proved. At the time of analysis, all dogs were dead. Mean and median survival times, measured from the beginning of radia tion, were 345 and 489 days, respec- tively. This was compared to mean survival times of 30-81 days reported in the literature for dogs with brain tumors that did not receive treatment. The median survival time of nine dogs treated with 39 Gy was 153 days and 519 days for five dogs that received 45 Gy.

It appears that radiation therapy prolongs survival times for dogs with brain masses. Although megavoltage therapy would be optimal, orthovolage radiation can be applied in total doses of 45 Gy in 3.75 Gy fractions over 28 days without untoward clinical side effects. Histopathologic evidence of multifocal demyelination and astrocytosis may be found.

Sydney M . Evans, V M D , MS Betsy Dayrell-Hart, V M D

William Powlis, M D Gertrude Christy, RTT

Thomas Van Winkle, V M D