SLOW-RELEASE CISPLATIN COMBINED WITH RADIATION FOR THE TREATMENT OF CANINE NASAL TUMORS

Thirteen dogs with malignant tumors of the nasal cavity were treated w ith a combination of slow release cisplatin and megavoltage radiation, Radiation was delivered on a Monday through Friday schedule using a 6 MV linear accelerator, The median total dose was 49.5 Gy (range 49.5- 56 Gy). Cisplatin was given using an open-cell polylactic acid polymer , impregnated with the drug and implanted intramuscularly at a distant site, as a slow release delivery system (OPLA(R)-Pt [THM Biomedical, Inc]). The median dose used was 60 mg/m(2) (range 60-100 mg/m(2)). Whe n combined with radiation, this delivery system caused no systemic dru g toxicity, and a local tissue reaction was seen in only two dogs. Acu te side effects to normal tissue from radiation mere not enhanced, as measured by subjective assessment, When compared to a group of histori cal controls that received radiation without OPLA-Pt, the dogs that re ceived combined radiation and cisplatin had longer overall survival ti mes, with a median of 580 days, The control group had a median surviva l of 325 days. Previously reported median survival times for comparabl e megavoltage radiation treatment range from 6 to 13 months. Some dogs in both groups also received adjuvant chemotherapy but this did not i nfluence survival time. By multivariate analysis, only the use of OPLA -Pt was found to significantly influence survival, with a p value of p = 0.023. Mega-voltage radiation and slow release cisplatin appears to be a well tolerated combination that may favorably affect survival of dogs with nasal tumors.