Radiobiology 2016

Assays for Tumor Response to Radiation • Clonogenic assays (plating assays): tumors are excised, reduced to single cells, and grown in a test environment - provide a direct measure of the surviving fraction of clonogenic cells.

- limitation: relationshipbetween clonogens (in test environment) and stemcells (in situ) is uncertain.

• Culturing as organoids: tumors are excised, reduced to single cells, and grown in 3D matrix - Measurement of tumor stem cells - Show potential to differentiate in all tumor subtype cells - lack of environmental factors,… vascularisation • In Situ assays (growth delay, tumor control): tumors left in place. - measure response of effective and potential stemcells. - limitation: no quantitation of stemcells; surviving fraction is difficult to assess.