Resistance in malignant tumors: can resistance assays optimize cytostatic chemotherapy?

The frequent resistance of malignant tumors to chemotherapy documents the fact that numerous patients are uselessly traumatized by highly toxic drugs. Investigations into this resistance have shown that many different mechanisms exist which can abolish the antitumor action of chemotherapeutics. So far, no safe method has been found to counteract this resistance. To date, the only way to avoid harm by an ineffective chemotherapeutic is to refrain from its use when resistance to it is detected. The present survey reports on the available assays that diagnose resistance reliably; sensitivity tests are excluded as being unreliable. Resistance assays are still not fully recognized in hospitals, despite the fact that they are able to optimize chemotherapy by eliminating treatment that is ineffective and merely harmful. Since the number of chemotherapeutics will increase enormously in the future, pharmacological cancer treatment cannot dispense with resistance assays.