[Probit analysis in assessing the results of radiation therapy of disseminated cancer of the tongue and floor of the mouth].

The results of radiation therapy were compared in 217 patients at advanced stages of cancer of the tongue (131) and fundus of the mouth (86) using split courses of conventional (SCF) and dynamic fractionation (SDF) and SDF combined with metronidazole. Dose-effect curves were evaluated by probit-analysis. SCF at a total focal dose increased from 64-76 up to 78-82 Gy did not improve therapeutic results. The predicted limits of efficacy were higher in SDF as compared to SCF. The most effective was the use of SDF in combination with metronidazole (one year after therapy discontinuation 52% of patients with cancer of the tongue and 36% of patients with cancer of the fundus of the mouth were alive). In a total focal dose increased up to 68-72 Gy a rise of efficacy in T3 was 11% for cancer of the tongue and 18% for cancer of the fundus of the mouth. This method permits the evaluation not only of the predicted limits of efficacy but also of a probable rate of improvement in a raised TFD.