Table 1:

Key points, advantages and disadvantages of different methods to measure chemosensitivity and resistance.

Name	Measures	Key point of the method	Advantage	Disadvantage
Viability assay	− The number of cells	− Cell counting with an exclusion dye	– Direct measurement	– Laborious– subjective
Colorimetric assays	− The metabolic activity of cells	− Metabolic conversion of a product by the cells, accompanied with change of color	– Easy and fast	– Indirect – Except Alamar blue, toxic to cells
Automated high throughput confocal microscopy	− Live and dead cells	− Automated high throughput confocal microscopy based method − Allows simultaneous analysis of a large number of drugs	– Useful for large scale drug sensitivity and resistance screening	– Does not consider the benign cell component
Clonogenic assay	− The ability of cells to grow and form colonies	− Single cell suspension is plated and the growing colonies are counted	– Distinguishes between cytostatic and cytotoxic effects– accurate	– Not suitable for cells which are unable to form colonies or low proliferating cells – Multiple drugs cannot be tested – Tumor cells are dissociated, the effect of extracellular environment is lost
Fluorescence Activated Cell Sorting (FACS)	− Apoptosis − Cell cycle progression− DNA content of cells	− Annexin/Propidium Iodide staining is combined with tumor specific immunological staining − Fluorescent-based assays where the dye interchalate with double stranded DNA	– Allows measurement of cytotoxic effects in a mixed cell population – Direct measurement	– Laborious if a large number of drugs are tested