Cancer is not one disease. It is many. Yet oncologists have long used the same blunt weapons to fight different types of cancer: cut the tumour out, zap it with radiation or blast it with chemotherapy that kills good cells as well as bad ones. New cancer drugs are changing this. Scientists are now attacking specific mutations that drive specific forms of cancer. A breakthrough came more than a decade ago when Genentech, a Californian biotech firm, launched a drug that attacks breast-cancer cells with too much of a certain protein, HER2. In 2001 Novartis, a Swiss drugmaker, won approval for Gleevec, which treats chronic myeloid leukaemia by attacking another abnormal protein. Other drugs take different tacks. Avastin, introduced in America in 2004 by Genentech, starves tumours by striking the blood vessels that feed them. These new drugs sell well. Last year Gleevec grossed $4.3 billion. Roche's Herceptin (the HER2 drug) and Avastin did even better: $6 billion and $7.4 billion respectively. The snag, from society's point of view, is that all these drugs are horribly expensive. Last year biotech drugs accounted for 70% of the increase in pharmaceutical costs in America, according to Medco, a drug-plan manager. Cancer plays a huge role in raising costs.