Repair of Potentially Lethal Radiation Damage<i>In Vitro</i>and<i>In Vivo</i>

Abstract

The repair of potentially lethal damage was studied in plateauphase cultures of human LICH cells in vitro and in NCTC-2472 mouse fibrosarcoma grown in vivo in both the ascites and solid forms. Solid tumors and old, slowly-growing ascites tumors repaired potentially lethal damage; the kinetics and amount of repair were similar to those found in plateau-phase cultures. Repair in vitro was associated with a change in the slope of the survival curve without an accompanying increase in the shoulder of the curve. The effects of repair of sublethal and potentially lethal damage were additive. Thus this repair is another factor which influences the response of tumors to fractionated irradiation.