Patients and politicians anxiously await and increasingly demand a 'cure' for cancer. But trying to control the disease may prove a better plan than striving to cure it, says Robert A. Gatenby. The German Nobel laureate Paul Ehrlich introduced the concept of 'magic bullets' more than 100 years ago: compounds that could be engineered to selectively target and kill tumour cells or disease-causing organisms without affecting the normal cells in the body. The success of antibiotics 50 years later seemed to be a strong validation of Ehrlich's idea.