CORRELATION BETWEEN INITIAL AND LONG-TERM RESPONSES OF SPONTANEOUS PET ANIMAL TUMORS TO HEAT AND RADIATION OR RADIATION ALONE

  • 1 January 1983
    • journal article
    • research article
    • Vol. 43  (12) , 5735-5741
Abstract
Most early-phase testing of new therapeutic modalities involves analysis of initial tumor response as opposed to estimation of long-term response. The validity of initial response rates to predict long-term responses was examined for tumors treated with radiotherapy alone compared with heat combined with radiotherapy. Pet animals (130) [cats or dogs] with either squamous cell carcinomas, melanomas, fibrosarcomas, mammary adenocarcinomas or mast cell sarcomas were randomized to receive radiation alone (XRT) or heat + radiation (.DELTA. + XRT). Responses to treatment were evaluated by response rates and response duration. The complete response (CR) rates were consistently higher for .DELTA. + XRT than for XRT across different histology groups. The combined therapy led to prolonged tumor response in all histological subgroups except melanomas, which had a longer response duration when treated with XRT alone (P = 0.043). This was in spite of a relatively high CR rate in that group (100% vs. 12.5% for .DELTA. + XRT and XRT, respectively). While no significant improvement in CR rate was observed for dermal squamous cell carcinomas treated with .DELTA. + XRT (XRT = 52.9%; .DELTA. + XRT = 68.8%), a significant improvement in response duration was noted (P = 0.002). These are 2 examples where CR rate did not predict long-term response. When all histological subgroups were combined (except melanomas), the CR rate was higher (P < 0.001), and response duration was prolonged (P = 0.031) for .DELTA. + XRT compared to XRT alone.

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