[Time factor in local radiotherapy (author's transl)].

This study was aimed at determining the influence of time factor in local radiotherapy in patients with spindle cell neoplasms of the skin or basal cell carcinomas of the face, treatable in a single plane. These neoplasma were treated using identical doses (6,000 rads distributed over the envelope isodose), but divided at random into two groups corresponsing to two different spreads (60 +/- 12 hours and 156 +/- 12 hours). The biological effects observed (rate of disappearance of the lesion, intensity of skin reaction, duration of skin reaction) showed no difference between the two types of treatment. This results is unexpected considering the important influence of time factor in the case of fractionated irradiation. In fact, if it is accepted that between 60 and 156 hours, cellular multiplication phenomena are equivalent to approximately 30 rads per day, the difference in spread the two types of treatment is not sufficient to give a significant result.