Dynamic computed tomography predicts tumor temperature and response to thermoradiotherapy in superficial and subsurface tumors

BACKGROUND. Dynamic computed tomography (CT) was performed on patients unde rgoing thermoradiotherapy for superficial or subsurface tumors, and the cor relation between tumor enhancement and tumor temperature during hyperthermi a was evaluated. The authors further investigated whether tumor enhancement by dynamic CT is predictive of tumor response to thermoradiotherapy. METHODS. Thermoradiotherapy was given to 26 patients. Radiotherapy consiste d of 40-70 gray. Hyperthermia was conducted over 3-5 sessions, and tumor te mperature was measured at each session. Dynamic CT was performed prehyperth ermia (within 1 week before the initiation of hyperthermia) and midtherapy (within 1 week after 2 sessions of hyperthermia). RESULTS. A complete response (CR) was obtained in 11 patients (42%) and eit her a partial response or no response (non-CR) in 15 (58%). There was no co rrelation between tumor enhancement obtained by prehyperthermia CT and tumo r temperature parameters or response. However, the Delta CTmax (maximum inc reased enhancement) by prehyperthermia and midtherapy CT was 39.0 +/- 18.9 HU and 26.1 +/- 14.2 HU, respectively, in CR patients, and 46.4 +/- 21.1 HU and 49.6 +/- 19.1 HU, respectively, in non-CR patients. This change in Del ta CTmax at midtherapy was significantly different between groups (P < 0.01 ). The Delta CTmax ratio for prehyperthermia and midtherapy CT studies corr elated with the average tumor temperature (P < 0.05). CONCLUSIONS. Tumor enhancement by prehyperthermia and midtherapy dynamic CT predicted tumor temperature during hyperthermia and response to thermoradi otherapy for superficial or subsurface malignancies. Cancer 1999;86:177-85. (C) 1999 American Cancer Society.