Relation between body size and temperatures during locoregional hyperthermia of oesophageal cancer patients

Purpose. To analyse the relation between patients' body size and temperatures during locoregional hyperthermia for oesophageal cancer. Methods. Patients were treated with neo-adjuvant chemoradiotherapy plus hyperthermia, given with the AMC-4 waveguide system. Temperatures were measured at tumour location in the oesophageal lumen using multisensor thermocouple probes. Systemic temperature rise (Tsyst) was monitored rectally. Steady-state tumour temperatures were expressed in terms of T90, T50 and T10, averaged over the five hyperthermia sessions, and correlated with patients' body mass, dorsoventral and lateral diameter and fat layer thickness, measured at tumour level using a CT scan made in treatment position. Fat percentage (Fat%) was estimated using diameters and fat layer thickness. Effective tumour perfusion (Wb) was estimated from the temperature decay during the cool-down period. Results. Temperatures were inversely related to body mass, diameters, fat layer thickness, and fat percentage. The strongest univariate correlations were found with lateral fat layer thickness, lateral diameter, and body mass. An increase in lateral diameter (2842 cm), or in lateral fat layer thickness (040 mm) or in body mass (50120 kg) all yielded a 1.5C decrease in tumour temperature rise. Multivariate correlation analysis proved that the combination of Fat%, Tsyst and Wb was most predictive for the achieved tumour temperatures, accounting for 81 12% of the variance in temperatures. Conclusions. Intra-oesophageal temperatures during locoregional hyperthermia are inversely related to patients' body size parameters, of which fat percentage is the most significant prognostic factor. These findings could be used to define inclusion criteria of new studies on intrathoracic hyperthermia