The following summary of their organizations studies concerning their treatment protocols was composed by Dr Page to be shared with all of Sylvia's feline loving friends. Sylvia sends her wet nose kisses to Dr Page for taking time out of his very busy schedule to assist us in our families effort to keep all of Sylvia's feline friends abreast of the very latest information available in the fight against this dreaded disease.

Post-Injection Sarcomas-The North Carolina State University, College of Veterinary Medical Experience

Post injection sarcomas began to impact our program in 1990. In 1989 we treated only 3 cats for sarcomas and these were non-vaccine sites. The number of cats treated has increased each year since then and 95% of all feline sarcomas now arise in the vaccine sites. We have treated over 100 cats since 1990 with various forms of therapy including surgery, radiation and chemotherapy. In 1991 we began to use radiation therapy and surgery together in a planned approach to attempt greater control. At that time little was known about the clinical management of injection-site sarcomas. Only one previous manuscript had been published (in 1979) regarding sarcomas in cats indicated results similar to sarcomas in other species (i.e. surgical control was dependent on aggressive management and the grade of the malignancy). Our combined treatment program was based on the work previously found to be successful in humans with sarcomas of this type. Although radiation therapy and surgery may be combined in several ways, our plan is based on the concept that radiation delivered before surgical removal of the tumor would help to sterilize the margins of the tumor and potentially reduce the size of the tumor thus improving the chances for complete surgical excision.

We have recently summarized our initial results (Cronin et al, Radiation therapy and surgery for fibrosarcoma in 33 cats. Veterinary Radiology and Ultrasound -in press). Since these initial cats were summarized we have treated approximately 60 more cats with this technique, with some modifications based on our previous experience. Although we have not thoroughly evaluated the later group I would like to provide a summary of the first group and our current recommendations for therapy of these tumors.

The group of cats included in the original series were similar to other reports in terms of age, breed, gender, number of previous surgeries for the tumor and tumor volume. The radiation treatment consisted of daily treatments (16 days M-F @ 300 rads / treatment). The cat recovered for 2-4 weeks and was returned for an aggressive surgical removal of the tumor and radiation field. Some of the surgical procedures included amputations or large soft tissue and bone resections depending on the site.

Nineteen of the 33 cats treated with the radiation and surgery had some form of tumor regrowth or metastasis (spread to other organs). Eight cats developed metastasis (26%) and this rate is considered high compared to other sarcomas and this information had not been previously known. Some of these cats also experienced local regrowth before, after or simultaneous with metastasis. An additional 11 cats had local regrowth without metastasis. 3 cats died of unrelated causes without recurrence or metastasis but were evaluated similarly to those cats dying of cancer to insure that the data would not overestimate our treatment outcome. In the entire group of cats the average time to regrowth or metastasis was about 14 months. The average time until death was about 20 months. The primary determinant of treatment success was the ability to achieve "clean margins" (no tumor observed on the edges of the resected tissue). Cats in this category had an average tumor-free survival of 23 months and 35% of cats were tumor free at 3, 4 and 5 years after treatment.

From this information we have modified our approach in several ways: 1) we have advised owners that the addition of chemotherapy may reduce the incidence of metastasis, 2) we increased the size of the radiation field, where possible based on critical surrounding normal tissue to more adequately treat cancer cells at the margin, and 3) we recommend a surgical procedure that is as aggressive as possible based on location.

We are in the process of summarizing the last several years of data and will report this information when it is completed. Our recommendations to owners with cats that have injection-site sarcomas include the following: 1) early, aggressive treatment is optimal. Persistent vaccine reactions (granulomas) should be removed and biopsied. Wide surgical excision of small (<2 cm diameter) tumors may be sufficient if margins are clean. The role of radiation therapy in small tumors is not yet defined, however, the same advantages apply to small as well as large tumors. Tumors greater than 2 cm in diameter, incompletely resected tumors or tumors that appear to have regrown after surgery are considered candidates for combined modality therapy. Surgical removal of the tumor should be conducted by someone familiar with aggressive soft tissue surgery including removal of some bone underlying the area of tumor growth. Several of our relapses occurred following less aggressive removal especially around boney structures not removed at the time of surgery such as the pelvis, vertebral column and shoulder blade.

There are some cats that have tumors that are not eligible for conventional radiation therapy or surgery due to their size or location. Radiation used in a palliative method or palliative chemotherapy may be useful for temporary control of signs related to tumor growth.

RL Page DVM, MS

Professor of Oncology

Diplomate ACVIM (Medicine / Oncology)

NOTE:

Radiology and Ultrasound has since been published with the following citation mentioned above:

Radiation therapy and surgery for fibrosarcoma in 33 cats.

AUCronin-K; Page-RL; Spodnick-G; Dodge-R; Hardie-EN; Price-GS; Ruslander-D; Thrall-DE SOVet-Radiol-Ultrasound.1998 Jan-Feb; 39(1) :51-6. ISSN1058-8183 LAENGLISH AB

Thirty-three cats with histologicallyconfirmed fibrosarcomas were treated with radiation therapy followed by surgery. The median (95% confidence interval) disease free interval and overall survival were 398 (261,924) and 600 (lower limit 515) days, respectively. There were 19 treatment failures; 11 cats had only local recurrence, 4 cats developed metastatic disease, 3 cats had local recurrence followed by metastasis, and 1 cat developed simultaneous local and distant disease. Twelve cats are alive and disease free. Two cats died without evidence of treatment failure. The presence of tumor cells at the margin of resected tissue after radiation was the only variable which influenced treatment success. The median (95% confidence interval) disease free interval in 5 cats with tumor cells at the margin of the resected specimen was 112 (94,150) days versus 700 (lower limit 328) days for 26 cats with negative tumor margins, p < 0.0001. We did not identify a relationship between tumor volume, number of prior tumor excisions, concomitant use of chemotherapy or various descriptors of the radiation therapy technique and disease free interval.

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