Preoperative
and Postoperative Radiation Therapy
for Soft-Tissue Sarcomas in 28 Cats
Ruslander DM,
Rassnick KM, Simon D, Northrup NC, Kristal O, Chretin JD, McCarthy RJ, Berg RJ
and Moore AS. Harrington
Oncology Program, Tufts University School of Veterinary Medicine, North Grafton,
MA, 01536
Feline soft-tissue sarcomas (STS) are associated with a local recurrence
rate exceeding 50% and a 20-30% metastatic rate.
Aims of this study were to prospectively evaluate megavoltage
radiotherapy (XRT) in preoperative and postoperative settings and the role of
chemotherapy in the management of cats with STS.
Records of 28 cats with STS treated between 5/98 and 4/00 were reviewed.
Cats with microscopic disease (n=18) were treated with 60 Gy in 20 daily 3.0 Gy
fractions. Cats
with gross disease (n=10) were treated as follows: 48 Gy preoperatively, 2 week
break, surgery and a 4 x 3.0 Gy postoperative boost.
Fifteen cats received adjuvant chemotherapy (doxorubicin 25 mg/m2
IV alternating with carboplatin 210 mg/m2 IV).
Patient and tumor factors were recorded.
Endpoints included recurrence, metastasis and overall survival calculated
from initiation of XRT.
Information from 28 cats was available for review (median follow-up 394d,
range 191-590d).
Eleven cats developed local recurrence.
Median time to recurrence was 190d (range 92-332d).
One cat developed metastasis (heart-base) and recurrence at 67 and 402
days, respectively.
Two cats developed pulmonary metastasis without recurrence at 160d and
217d. Twelve
cats are disease-free (range 147-590d, median 372d).
One cat was lost to follow-up at 404 days.
Two cats were euthanized for splenic MCT and oral SCC at 312 and 207d,
respectively. Eleven
cats died of tumor-related causes (range 162-535d, medium 410d).
Fourteen cats are still alive (range 191-590d, medium 371d).
Radiation toxicity was minimal, consisting of dry desquamation and
alopecia. One
cat developed presumptive transient myelopathy that responded to prednisone.
Three cats in the preoperative group developed surgical complications, 2
requiring surgical repair.
Megavoltage radiotherapy, delivered preoperatively or postoperatively and adjuvant chemotherapy is feasible and well-tolerated, although the overall efficacy is difficult to assess. The high rate of local recurrence indicates that novel strategies should be employed.
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