Tissue microarrays for predictive molecular pathology

Preparing for a TITANIC problem The advent of a novel category of anticancer drugs targeting individual genes is greatly affecting pathology and it appears that a new discipline—predictive molecular pathology—will become important in our field. For example, Herceptin (trastuzamab) treatment can only be used against tumours expressing the HER-2 oncogene1 and STI571 (Glivec) is highly efficient against tumours expressing c-kit (CD117).2 Because these target genes can be expressed in many different tumour types, oncologists are now increasingly demanding HER-2 and c-kit analyses for all of their patients so that they can potentially benefit from new drugs. The number of such analyses, often performed many years after the removal of the primary tumour, increases rapidly as more patients with cancer and clinicians become aware of the potential availability of new “miracle” drugs. Currently, the demand for retrospective c-kit and HER-2 analyses can be met using the tools of traditional molecular pathology. However, what would happen if all living patients with cancer became aware of a new drug from which they could benefit if their tumour expressed one particular gene? The logistical problems connected to such a mass demand for analyses would be comparable to the situation on the sinking Titanic with a shortage of lifeboats more than 90 years ago. Alone in a small country like Switzerland (7000 000 inhabitants), there is an estimated number of > 150 000 living people with known potentially life threatening cancer. Tens of thousand of these patients would die of …