Cancer: Treatment or prevention?

Cancer chemotherapy, often in combination with other therapies, has been succesful in the treatment of some cancers, but its failure to affect the common solid cancers has meant that mortality from cancer has changed little over the past forty years. Calls for the money spent on treatment to be transferred to education, early detection, and prevention are increasing, despite lack of solid evidence that these approaches are any more likely to be effective than therapy. Conventional routes to the discovery of anticancer drugs, which have relied on extensive and costly testing in animal models to select a small number of potentially useful drugs, are now being replaced in favour of more widespread testing of a greater range of agents in early clinical trials. Drug development programmes are being introduced to facilitate clinical trials at a fraction of the time and cost of more conventional programmes. A whole range of new types of anticancer agents are now in Phase I/II clinical trials. Should none of these prove to be effective against the common solid cancers there will be renewed calls to divert research into early detection and prevention. Of particular interest has been the finding that many anticarcinogens used by experimentalists over the years are specifically toxic to transformed cells expressing aberrant signal transduction pathways. Agents of this type may therefore remove partially transformed cells and thus form the basis for new cancer prevention programmes.