Relationships between thermal dose parameters and the efficacy of definitive chemoradiotherapy plus regional hyperthermia in the treatment of locally advanced cervical cancer: data from a multicentre randomised clinical trial.

PURPOSE: To evaluate the contribution of the thermal dose parameters during regional hyperthermia (HT) treatment to the clinical outcomes in patients with cervical carcinoma (CC) who received chemoradiotherapy (CRT) plus HT. MATERIALS AND METHODS: Data from a multicentre randomised clinical trial of concurrent CRT + HT vs. CRT alone were used to evaluate the efficacy and safety of this combination therapy in the CC patients. The intrarectal temperatures of patients undergoing HT were recorded. The complete thermal data of 47 (92%) of the 51 patients in the CRT + HT group were available for the thermal analysis. Thus, 47 patients who received CRT + HT were included in the present study. RESULTS: Among the patients who received CRT + HT, a higher CEM43T90 (≥1 min) value (a thermal dose parameter) was significantly associated with better local relapse-free survival in both univariate (p = 0.024) and multivariate (p = 0.0097) analyses. The disease-free survival of the patients with higher CEM43T90 (≥1 min) values tended to be better in comparison to patients with lower CEM43T90 (<1 min) value (p = 0.071). A complete response tended to be associated with the CEM43T90 (p = 0.056). Disease-free survival, local relapse-free survival and complete response rate for patients with higher CEM43T90 (≥1) were significantly better than those for patients with CRT alone (p = 0.036, p = 0.036 and p = 0.048). CONCLUSIONS: Dose-effect relationships between thermal dose parameters and clinical outcomes were confirmed in the CC patients treated with a combination of CRT + HT. This study also confirmed that HT with lower CEM43T90 is insufficient to achieve a significant hyperthermic sensitisation to CRT.

The usefulness of mobile insulator sheets for the optimisation of deep heating area for regional hyperthermia using a capacitively coupled heating method: phantom, simulation and clinical prospective studies.

PURPOSE: To evaluate the feasibility and efficacy of deep regional hyperthermia with the use of mobile insulator sheets in a capacitively coupled heating device. MATERIALS AND METHODS: The heat was applied using an 8-MHz radiofrequency-capacitive device. The insulator sheet was inserted between the regular bolus and cooled overlay bolus in each of upper and lower side of the electrode. Several settings using the insulator sheets were investigated in an experimental study using an agar phantom to evaluate the temperature distributions. The specific absorption rate (SAR) distributions in several organs were also computed for the three-dimensional patient model. In a clinical prospective study, a total of five heating sessions were scheduled for the pelvic tumours, to assess the thermal parameters. The conventional setting was used during the first, third and fifth treatment sessions, and insulator sheets were used during the second and fourth treatment sessions. RESULTS: In the phantom study, the higher heating area improved towards the centre when the mobile insulator sheets were used. The subcutaneous fat/target ratios for the averaged SARs in the setting with the mobile insulator (median, 2.5) were significantly improved compared with those in the conventional setting (median, 3.4). In the clinical study, the thermal dose parameters of CEM43°CT90 in the sessions with the mobile insulator sheets (median, 1.9 min) were significantly better than those in the sessions using a conventional setting (median, 1.0 min). CONCLUSIONS: Our novel heating method using mobile insulator sheets was thus found to improve the thermal dose parameters. Further investigations are expected.

Methods and pitfalls of measuring thermal preference and tolerance in lizards.

Understanding methodological and biological sources of bias during the measurement of thermal parameters is essential for the advancement of thermal biology. For more than a century, studies on lizards have deepened our understanding of thermal ecophysiology, employing multiple methods to measure thermal preferences and tolerances. We reviewed 129 articles concerned with measuring preferred body temperature (PBT), voluntary thermal tolerance, and critical temperatures of lizards to offer: a) an overview of the methods used to measure and report these parameters, b) a summary of the methodological and biological factors affecting thermal preference and tolerance, c) recommendations to avoid identified pitfalls, and d) directions for continued progress in our application and understanding of these thermal parameters. We emphasize the need for more methodological and comparative studies. Lastly, we urge researchers to provide more detailed methodological descriptions and suggest ways to make their raw data more informative to increase the utility of thermal biology studies.

Definitive radiotherapy plus regional hyperthermia for high-risk and very high-risk prostate carcinoma: Thermal parameters correlated with biochemical relapse-free survival.

PURPOSE: The aim of this study was to assess the efficacy of definitive radiotherapy (RT) plus regional hyperthermia (HT) and investigate the potential contribution of HT to clinical outcomes in patients with prostate carcinoma. MATERIALS AND METHODS: Following our institution's treatment protocol, HT was combined with RT to improve clinical outcomes in selected patients with high-risk or very high-risk prostate cancer. Data from 82 patients treated with RT plus HT and 64 patients treated with RT alone were retrospectively analysed. RESULTS: Median follow-up duration was 61 months. The 5-year biochemical disease-free survival (bDFS) rate for the 82 patients treated with RT plus HT was 78%, whereas bDFS for the 64 patients treated with RT alone was 72%; this difference was not significant. Among the 75 patients treated with RT plus HT who underwent intra-rectal temperature measurements, higher thermal parameters were significant prognostic indicators of improved bDFS by univariate analysis. A higher CEM43 °CT90 thermal parameter and a T stage of T1-2 were significant prognostic factors based on multivariate analysis. The 5-year bDFS rates for the 40 patients with a higher CEM43 °CT90 and the 64 patients treated with RT alone were significantly different, whereas 5-year bDFS for the 35 patients with a lower CEM43 °CT90 and the 64 patients treated with RT alone were not. CONCLUSIONS: The addition of HT with higher thermal parameters to RT may improve bDFS for patients with high-risk or very high-risk prostate cancer. These findings also demonstrate the importance of careful selection of treatable patients with higher thermal parameters.

Definitive radiotherapy plus regional hyperthermia for high-risk and very high-risk prostate carcinoma: Thermal parameters correlated with biochemical relapse-free survival.

PURPOSE: The aim of this study was to assess the efficacy of definitive radiotherapy (RT) plus regional hyperthermia (HT) and investigate the potential contribution of HT to clinical outcomes in patients with prostate carcinoma. MATERIALS AND METHODS: Following our institution's treatment protocol, HT was combined with RT to improve clinical outcomes in selected patients with high-risk or very high-risk prostate cancer. Data from 82 patients treated with RT plus HT and 64 patients treated with RT alone were retrospectively analysed. RESULTS: Median follow-up duration was 61 months. The 5-year biochemical disease-free survival (bDFS) rate for the 82 patients treated with RT plus HT was 78%, whereas bDFS for the 64 patients treated with RT alone was 72%; this difference was not significant. Among the 75 patients treated with RT plus HT who underwent intra-rectal temperature measurements, higher thermal parameters were significant prognostic indicators of improved bDFS by univariate analysis. A higher CEM43 °CT90 thermal parameter and a T stage of T1-2 were significant prognostic factors based on multivariate analysis. The 5-year bDFS rates for the 40 patients with a higher CEM43 °CT90 and the 64 patients treated with RT alone were significantly different, whereas 5-year bDFS for the 35 patients with a lower CEM43 °CT90 and the 64 patients treated with RT alone were not. CONCLUSIONS: The addition of HT with higher thermal parameters to RT may improve bDFS for patients with high-risk or very high-risk prostate cancer. These findings also demonstrate the importance of careful selection of treatable patients with higher thermal parameters.

Temperature Dependence of Tissue Thermal Parameters Should Be Considered in the Thermal Lesion Prediction in High-Intensity Focused Ultrasound Surgery.

This study considers the temperature-dependent thermal parameters (specific heat capacity, thermal diffusivity and thermal conductivity) used when predicting the temperature rise of tissue exposed to high-intensity focused ultrasound (HIFU). Numerical analysis was performed using the Khokhlov-Zabolotskaya-Kuznetsov equation coupled with a bioheat transfer function. The thermal parameters were set as the functions of temperature using experimental data. The results revealed that, for liver tissue exposed to HIFU with a focal intensity of 3000 W/cm2 for 10 s, the predicted focal temperature rise was 23% lower and the thermal lesion area 41% smaller than those predicted without considering the temperature dependence. The prediction was validated by experimental observations on thermal lesions visualized in a tissue-mimicking phantom. The present results suggest that temperature-dependent thermal parameters should be considered in the prediction of HIFU-induced temperature rise to avoid lowering ultrasonic output settings for HIFU surgery. The aim of the present study was to investigate how significantly the temperature dependence of the thermal parameters affects the thermal dose imposed on the tissue by a typical clinical HIFU device. A numerical simulation was performed using a thermo-acoustic algorithm coupling the non-linear Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation (Meaney et al. 1998; Filonenko and Khokhlova 2001) and a bio-heat transfer (BHT) equation (Pennes 1948). Thermal parameters of liver tissue were modeled in the present study as functions of temperature and were incorporated into the BHT equation to compensate for the variations in thermal parameters with temperature. Experimental validation was achieved by comparing the predictions with the thermal lesions formed in the tissue-mimicking phantoms.