Radiobiology 2016

Regrowth Delay Assay

• Comparison of growth curves of treated and untreated tumors gives the delay caused by treatment. • Relationshipbetween growth delay and surviving fraction of stem cells is complex. • Regrowing cells have different environment: surrounded by dead and dying cells; vascular network is already in place.

• Tumor bed effect

Growth Kinetics of Tumors, G.G. Steel, 1977