Chemotherapy is one of the principal modes of treatment for cancer, but the effectiveness of chemotherapy is limited by drug resistance. During cancer treatment, tumours that were initially sensitive but eventually become insensitive (we called resistant) to further treatment. Scientists have identified a number of possible mechaniss that drives drug resistant. Drug-resistant related cancer gene mutations were found, but these mutations are usually found after chemotherapy and do not pass on to next generation.
Do you think that cancer drug-resistance is a result of evolution? If yes, do you think that all human will be drug-resistant within a few generations? Otherwise, what makes you think that cancer drug resistant is not an example of evolution.