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.