Abstract
Drug resistance is the major reason for failure in cancer chemotherapy. Resistance
may be either pre-existent (intrinsic resistance), or induced by drugs (acquired resistance).
So far, no strategy has been found to overcome resistance, which is based on highly
complex and individually variable biological mechanisms. In present clinical practice,
drug resistance can only be recognized during treatment, after long lag times. Thus
diagnostic tests are required, indicating resistance at an earlier stage, in order
to avoid unnecessary medication, frequently associated with toxic side-effects.
A number of new anti-cancer drugs are now available. In contrast to the unspecifically
acting cytostatic chemotherapy, these compounds have targeted actions. However, as
recent studies have shown, resistances and severe side-effects can also be found with
targeted drugs.
With the increasing number of new treatment regimens, the early diagnosis of resistance
will optimize therapy, and indeed will be indispensable for individual cancer therapy.
The resistance assays available for use in clinical practice should be integrated
into cancer therapy. Research into this neglected area needs to be intensified.
Key words
Cancer drug therapy - Drug resistance, resistance mechanisms, resistance reversal
- Individualised cancer therapy - Predictive tests
