Only three strategies are available for controlling cancer, prevention, screening and treatment. Lung cancer causes more deaths than any other type of cancer. A major cause of the disease is  51  known; there is no good evidence that screening is of much help; and treatment  52  in about 90 per cent of all cases. At present, the main strategy must be prevention. This may not always be true, of course, as for some other types of cancer, research over the past few decades has produced some important progress in prevention, screening or treatment. If, however, we consider not what research may one day offer but what today's knowledge could already deliver that is not being delivered, then the most practicable and cost-effective opportunities for  53  premature death from cancer, especially lung cancer, probably involve neither screening nor improved treatment, but prevention.

This conclusion does not depend on the unrealistic assumption that we can  54  tobacco. It merely assumes that we can reduce cigarette sales appreciably by raising prices or by expanding the type of education that already appears to have had a  55  effect on cigarette consumption by white-collar workers, and that we can substantially reduce the amount of tar  56  per cigarette. The practicability of preventing cancer by such measures applies not only in those countries, such as the US, where, because cigarette smoking has been common for decades, 25-30 per cent of all cancer deaths now involve lung cancer, but also in those where it has become  57  only recently. Countries where cigarette smoking is only now becoming widespread can expect enormous increases in lung cancer during the 1990s or early in the next century, unless prompt effective action is taken against the habit.

There are four reasons why the prevention of lung cancer is of such overwhelming importance: first, the disease is extremely common, causing more deaths than any other type of cancer now  58 ; secondly, it is generally incurable; thirdly, effective, practicable measures to reduce its incidence are already reliably known; and, finally,  59  tobacco consumption will also have a substantial  60  on many other diseases.