IMPORTANCE OF MINIMUM TUMOR TEMPERATURE IN DETERMINING EARLY AND LONG-TERM RESPONSES OF SPONTANEOUS CANINE AND FELINE TUMORS TO HEAT AND RADIATION

  • 1 January 1984
    • journal article
    • research article
    • Vol. 44  (1) , 43-50
Abstract
A total of 130 dogs and cats with squamous cell carcinomas, melanomas, fibrosarcomas, mammary adenocarcinomas or mast cell sarcomas were randomized to recive radiation (XRT) or heat plus XRT. Time-temperature data for each monitored tumor location were converted to degree-minutes or equivalent minutes at 43.degree. C (Eq43). Response rates and durations of response were compared for subgroups of histology, volume, site and heat treatment method. Thermal gradients existed in all heated tumors. The influence of these gradients on tumor response was examined by correlation of response with degree-minutes and Eq43 minima, maxima, averages and ranges with prognostic subgroups as classified by volume, site or treatment method. The coolest part of the tumor governed the biological response to combined heat + XRT. Tumors which received a minimum of 35 Eq43 had significantly longer durations of response than did those receiving XRT alone or < 3 Eq43 (P .ltoreq. 0.006 and 0.014, respectively; log-rank test). Broad temperture ranges were associated with power-limiting hot spots and invariably led to underheating in other areas of tumor. Multivariate analysis found minimum Eq43 on the 1st treatment to be the best predictor of long-term response (P < 0.05). Other biological covariates of site, volume and histology contributed strength to the model, which was independent of Eq43 (P < 0.05).