Orthovoltage radiation and weekly low dose of doxorubicin for the treatment of incompletely excised soft-tissue sarcomas in 39 dogs

The efficacy and toxicity of orthovoltage radiation therapy and concurrent low doses of doxorubicin for the treatment of incompletely excised soft-tissue sarcomas in 39 dogs was investigated retrospectively. The 39 dogs had 40 soft-tissue sarcomas and received 51 Gy orthovoltage radiation in 17 daily 3 Gy fractions; they also received 10 mg/m 2 doxorubicin once a week administered intravenously one hour before the dose of radiation. The median follow-up time was 910 days. The tumours recurred locally in seven of the dogs, in five of them within the radiation field; the median time to their recurrence was 213 days (range 63 to 555 days). Six of the dogs developed a distant metastasis after a median time of 276 days (range eight to 826 days). The one-year and two- to four-year tumour control rates were 84 per cent and 81 per cent, respectively, and the one-, two- and three- to four-year survival rates were 85 per cent, 79 per cent and 72 per cent, respectively. Tumours with a mitotic rate of more than 9 per 10 high-power fields were significantly more likely to recur, and the dogs with such tumours survived for significantly shorter periods.