PATTERNS OF CHANGES OF TUMOR TEMPERATURES DURING CLINICAL HYPERTHERMIA - IMPLICATIONS FOR TREATMENT PLANNING, EVALUATION AND CONTROL

The patterns of changes in tumour temperatures were studied at selecte d times throughout 104 hyperthermia sessions. Temperature change patte rns were analysed in the context of the known patterns of change of th e applied power. First, of 69 extracranial treatments analysed, 74% in dicated relatively flat temperatures at constant applied power during a major portion of the treatment, thereby indicating that during that time there were no major changes in any of the physical or physiologic al tissue parameters which contribute to the ability of the tumour tis sue to remove energy (Pattern 1). Second, after reaching an initial st eady state, approximately 14% of these extracranial treatments showed either steadily decreasing temperatures at constant power, or constant temperatures at steadily increasing applied power, thereby indicating that the tumour's ability to remove energy was steadily increasing in lime following the initial steady state (Pattern 2). Finally, after r eaching an initial steady state, the remaining 12% of these treatments showed a pronounced decrease in temperature occurring about 10-20 min into the treatment followed by increasing temperatures or levelling o ff of temperatures at a higher value than the temperature minimum that had occurred, all at constant applied power (Pattern 3). Of 35 brain treatments analysed, 80% followed Pattern 1, 14% followed Pattern 2, a nd 6% followed Pattern 3. Intratumoral heterogeneity was evident in so me cases with approximately 44% of all treatments having at least one individual temperature sensor change in a manner that did not follow t he average direction of change when all sensors were combined. For sev en patients with permanent probes, the patterns of change presented in the first treatments were also observed during six out of seven of th e second treatments. In addition, three out of the five patients who h ad an evaluable third treatment showed a pattern of change during that third treatment that was similar to the pattern observed in both trea tment one and treatment two.