ARCON - CURRENT STATUS - SUMMARY OF A WORKSHOP ON PRECLINICAL AND CLINICAL-STUDIES

The current status of the experimental and clinical studies of ARCON w as presented. This is a new approach aimed at increasing the effective ness of radiotherapy by acceleration in order to avoid tumour cell reg eneration during therapy and using two forms of radiosensitizer of hyp oxic cells. The background knowledge about human tumour proliferation and oxygenation was expertly reviewed. New experimental data were pres ented for Various aspects of carbogen, Nicotinamide and a range of oth er potential sensitizers. These included mechanistic investigations, r adiobiological studies of clinically relevant dose levels, tumour and normal tissue effects, pharmacology and blood flow measurements. Clini cal data for both toxicity and initial estimates of the tumour respons e were presented. Extensive discussions about the side effects of Nico tinamide took place. The main conclusions from the preliminary clinica l results were encouraging, especially in head and neck and bladder tu mours. Two studies showed that local control is considerably increased compared with previous experience and with results from centres of ex cellence elsewhere. several other clinicians reported optimism. So far , ARCON has not been taken into randomized clinical trials and the dat a are therefore still, of necessity, compared with historical controls or with general clinical experience.