Early report of correlation between the thermal dosage and the treatment effect of hyperthermia in combination with chemoradiotherapy for esophageal cancer patients

Background/Aims: It is known to be difficult to determine thermal dosage in clincal tumor treatment. The aim of this study is to examine whether the quantitative heating dose reflects tha treatment effect in esophageal cancer. Methodology: Hyperthermo-chemoradiotherapy was performed on 14 patients with advanced esophageal cancer. The heating dosage was calculated as an integration of the isoeffective dose at 43°C using the following formulas: Δteq(T)=2(^T-43) • Δt (second) -- (a) (≥42.5°C) Δteq(T)-2(^42.5-43) • 6(^T-42.5) • Δt (second) -- (b) (<42.5°C) When hyperthermia continued at the same temperature for 2 seconds or more, the temperature was regarded as the heating temperature, and the cumulative time was defined as the thermal dose which was administered during the heating period. Results: Nine patients were resectable and the remating 5 patients were categorized as non resectable. The treatment effect was evaluated by an esophagram and an endoscopic examination both pre- and post-hyperthermo-chemoradiotherapy. Five patients were regarded to demonstrate a complete response, while 2 showed a partila response and 8 demostrated no change, respectively. The maximal cumulattive heating time was 2,312 seconds in the complete response group, 1,811 seconds in the partial response group and 1,260 seconds in the no change group (p=0.038). The minimal and average cumulative heating time did not show any correlation with the treatment effect. Conclusions: Our results indicate that the thermal doses calculated by those formulas were adequate for clinical hyperhermia in esophageal cancer patients.