[The current evaluation of radiotherapy treatment results].

PURPOSE: Efficacy of treatment is expressed in terms of postradiotherapeutic tumor volume decrease and halving time indicating regression rate. Tumors of the same histology and TNM stage were compared after different treatments. Prior to this comparative study tumor volume changes and halving time were tested for judging the efficacy of chemotherapeutic treatment of 765 patients with lung metastasis. PATIENTS AND METHODS: Tumor volume was determined by CT planimetry before and after radiotherapy in 56 tumor patients (42 lung tumors, 14 thyroid tumors). The rate of regression, i.e., the halving time was calculated on the basis of exponential curve. Fourteen thyroid tumor patients given telecobalt and photon irradiation for post-operative recurrence formed a separate group of patients. Halving time was determined at 30-day intervals, the values were qualified as "fast", "moderately fast", "moderately slow" and "slow".
RESULTS: Partial remission rate of patients treated by telecobalt irradiation was not higher than 60%, accompanied by fast halving time. With those receiving photon irradiation, however, partial remission reached even 70%, also with a fast halving time. In both groups minimal remission was associated with moderately fast halving time. The partial remission of recurring thyroid tumor patients receiving telecobalt irradiation was partly fast, partly moderately fast. Their minimal remission data developed with a moderately fast halving time, although chemotherapy subsequent to radiotherapy did not result in regression.
CONCLUSION: Appraisal of radiotherapeutic efficacy is based on the simultaneous monitoring of decrease in tumor volume (%) and halving time. It is to be stressed that neither the planimetric volume determination nor the halving time data can be taken as absolute values, since they are subject to other factors. In authors opinion, the most effective methods of the following of the tumor regression is the planimetric volume measurement calculated by CT, in the clinical praxis in recent time.