Comparison of radiological and pathohistological response to neoadjuvant chemotherapy combined with regional hyperthermia (RHT) and study of response dependence on the applied thermal parameters in patients with soft tissue sarcomas (STS).

To compare the radiological criteria RECIST, WHO, and tumor volume for evaluation of tumor response in patients with soft tissue sarcomas (STS) showing either good or poor pathohistological response to neoadjuvant chemotherapy combined with regional hyperthermia, and to examine the dependence of the findings on the applied thermal dose. 19 patients with pathohistological complete response (no vital tumor cells, group 1) and 27 with pathohistological no response (<25% necrosis, group 2) were selected from our previous clinical trials. The change in tumor size before and after therapy was determined. Intratumoral temperature (T(90)) and thermal dose (CEM 43 degrees C T(90)) were calculated for 13 patients. In the first group, 6 partial response (PR) and 13 stable disease (SD) according to RECIST, 7 PR and 12 SD according to WHO, 7 PR and 12 SD according to volumetric criteria were evaluated. In the second group, the results were 10 PR and 17 SD (RECIST), 9 PR and 18 SD (WHO), 8 PR and 19 SD (volume). The concordance of these criteria was 73.7% in group 1 and 74% in group 2. PR and SD were equally distributed in both groups (p > 0.421). Thermal parameters were not different between the groups (p > 0.327). SD or PR in radiological response assessment does not correlate with the pathohistological response after neoadjuvant thermochemotherapy. RECIST, WHO and volumetric criteria for response evaluation in STS are in substantial agreement. For irregularly shaped lesions, volumetric criteria seem to be more appropriate.