Summary of:

          “Treatment with a Combination of Doxorubicin, Surgery,
             and Radiation versus Surgery and Radiation Alone for Cats with
             Vaccine-Associated Sarcomas: 25 Cases (1995-2000)”  

 Vaccine associated sarcomas (VAS) in cats are a devastating disease that has affected many families in North America.  For this reason, a number of researchers have focused on these tumors in recent years.  Although much work has been done to characterize the etiology and behavior of these tumors, the optimal treatment remains unclear.  Previous reports on the efficacy of surgery, radiation and/or chemotherapy have been complicated by variable treatment types and timing included in the evaluation so that the relative value of each modality is unclear. What we hoped to achieve in this study was to be able to assess whether the outcome of cats treated with doxorubicin chemotherapy after surgery and radiation was better than that of cats just treated with surgery and radiation therapy.

What we found was, overall, the recurrence rate of these tumors after surgery and radiation (plus or minus chemotherapy) was 28% and we did not document any cases of metastasis (or spread of the tumor elsewhere).  The (median) time for a tumor to recur in the group that received chemotherapy after surgery and radiation, if they did, was 661 days.  The (median) time for a tumor to recur in the surgery and radiation alone group was not achieved (meaning the data had not “matured” enough for this calculation to be made) at the time of writing this paper but was over 452 days.  The median survival time was 674 days for the group treated with doxorubicin combined with surgery and radiation, and 842 days for the group treated with surgery and radiation only.  When these two times were compared statistically, no significant difference was found. When the time to recurrence and survival time were compared for cats having had one surgery versus those that had undergone greater than one surgery, no significant difference was found.

The conclusion of this study was that there was no significant difference in the treatment of cats with surgery and radiation alone versus surgery, radiation and doxorubicin (adriamycin) chemotherapy.  However, it should be noted that the number of cases in this study was quite small (only 25 cats total) and so any conclusions should be made with caution.  Although this study did not prove a difference between these two groups, if these tumors do metastasize, as has been shown in other studies, following surgery and radiation with chemotherapy would be the best way to decrease the chance of metastasis.  

Dr. Victoria S. Bregazzi
DVM, MS, DACVIM
Assistant Clinical Specialist   
Department of Small Animal Clinical Sciences
University of  Minnesota, College of Veterinary Medicine