RADIATION-THERAPY AND SURGERY FOR FIBROSARCOMA IN 33 CATS

Thirty-three eats with histologically confirmed fibrosarcomas were tre ated with radiation therapy followed by surgery, The median (95% confi dence interval) disease free interval and overall survival were 398 (2 61,924) and 600 (lower limit 515) days, respectively. There were 19 tr eatment 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 c ats are alive and disease free, Two cats died without evidence of trea tment failure. The presence of tumor cells at the margin of resected t issue after radiation was the only variable which influenced treatment success, The median (95% confidence interval) disease free interval i n 5 cats with tumor cells at the margin of the resected specimen was 1 12 (91,150) days versus 700 (lower limit 328) days for 26 cats with ne gative tumor margins, p<0.0001. We did not identify a relationship bet ween tumor volume, number of prior tumor excisions, concomitant use of chemotherapy or various descriptors of the radiation therapy techniqu e and disease free interval.