Attempt to Develop Reduced Radio-Sensitivity in Jensen Rat Sarcoma by Means of Roentgen Irradiation

Abstract

The author gives a short survey of the most important views which have been advanced as to the acquired reduction of radio-sensitivity in malignant tumors; reviews some exptl. work which throws light on this phenomenon; describes the irradiation technique employed, and gives the "lethal" dose in vivo for the laboratory''s strain of Jensen rat sarcoma as 4,000-4,500 r. He irradiated Jensen tumors in vivo with sublethal x-ray doses and found a reduced radio-sensitivity in most of the descendants of the earlier irradiated tumors. This reduced sensitivity seems to be the direct result of the effect of irradiation on the tumor cells; it is accompanied by slower growth, lower incidence, a higher content of collagen substance and a smaller number of mitoses.