Clinical dose-response curves of human malignant epithelial tumours

TLDR

Radiation therapy for epithelial tumours should be individualized based on histology, cell count, anoxia, and kinetics, yet histological variety does not alter radiosensitivity, and reoxygenation during treatment is considered essential for tumour control. The study correlates tumour volume with required doses for high control rates and examines repopulation potential by comparing split‑course technique outcomes with an 850 rads weekly dosage rate. Clinically derived dose‑response curves for subclinical lymphatic disease reveal that optimal doses and treatment times vary with anatomical site and tumour type, and that larger, poorly vascularised tumours achieve higher control rates with longer treatment times, indicating a role for reoxygenation.

Abstract

Optimally, the total radiation dose, over-all treatment time, and fractionation should be individualized for every tumour on the basis of histology, the number of malignant cells, the percentage of anoxic cells, and the kinetics of that particular tumour. The histological variety within the epithelial tumours does not affect radiosensitivity. Dose-response curves obtained clinically are shown for subclinical disease in the lymphatic areas. Correlation is attempted between the volume of cancer and the doses necessary to obtain a high percentage of controls. It is shown that, depending upon the anatomical site and the clinical variety of the cancer, the doses and treatment times may be different. Reoxygenation during treatment has been considered necessary to explain the control of human cancers by irradiation. The percentage of controls of very large, poorly vascularized tumour masses irradiated with long treatment times compared with shorter treatment times suggests that reoxygenation may be a factor. Some reflections are made on the repopulation potential of malignant cells by comparing results obtained with the split-course technique versus 850 rads weekly dosage rate.