Tumour regression as a guide to prognosis: a study with experimental animals

Publisher Website
Google Scholar
Abstract
An analysis was made of the relationship between regression during therapy and the probability of local control in a group of mice treated with single doses and fractionated doses of X rays. The tumors were 1st generation transplants from spontaneous mammary carcinomas in C3H mice and were irradiated with single doses, 3F[fractions]/4 days, 9F/10 days, 9F/18 days or 15F/18 days. The size of the smallest radiation dose approached those encountered in clinical radiotherapy. A significant correlation was observed between shrinkage during the treatment period and local control at 150 days, for 3 of the 4 fractionated schedules. A weaker correlation was observed for shrinkage within a week after single doses, and shrinkage during treatment with 9 fractions in 18 days. The rate of shrinkage is an inherent characteristic of each individual tumor and does not reflect the number of cells killed. Shrinkage in some tumors during the course of therapy may result in more extensive reoxygenation which makes these tumors more sensitive to subsequent doses of the fractionated course. The degree of shrinkage within the period of fractionated irradiation was a useful prognostic guide to ultimate local control in individual tumors.