[gdpawel]

Due to almost all patients being treated with combination chemotherapy, gene expression cannot even be calibrated without the use of a "functional" profiling assay. The functional profiling assay can actually integrate all the gene expression into one convenient test result.

Functional profiling uses a variety of metabolic and apoptotic measurements to determine if a specific drug (or combinations) are successful at killing a patient's cancer cells.

No gene-based test can discriminate differing levels of anti-tumor activity occurring among different targeted therapy drugs. Nor can a gene-based test identify situations in which it is advantageous to combine a targeted drug with other types of cancer drugs.

No matter what method is used to measure mRNA made from individual genes, to see if the expression of what genes correlates best with whatever (in this case, estrogen receptor), it's not quite ready for prime time as a clinical lab test for drug selection.

I would have hoped that scientists use DNA microarry analysis and cell function analysis to identify which drugs affect the tumor and create treatment plans that fit the tumor and the patient like a glove. What you want to measure are effects on the disease in the patient.

Cell culture work on fresh human tumors is labor intensive, defies automation and requires maximal individualization. Doesn't lend itself to "high throughput" which is the biotech/biomedical buzzword of the day.