Lung cancer has been one of the most important epidemics of the twentieth century. Late-nineteenth-century physicians and surgeons rarely diagnosed lung cancer and, even though techniques for making the alternative and more frequent diagnosis of tuberculosis were only partly developed at that time, it is unlikely that they were failing to make the diagnosis and much more likely that lung cancer was a medical rarity at that time. Now lung cancer is, in all probability, the commonest cancer in the world, with nearly 700.000 cases per year. In the United Kingdom, it accounts for 25 per cent of cancer deaths.The epidemic has been especially damaging. The disease strikes down men who are still economically productive and have dependent families. Sadly, the outlook for a patient diagnosed as having lung cancer remains one of the most dismal of all cancer diagnoses. Whereas the surgeon may hope to cure a third or a half of all of the patients whom he treats for other common cancers, the situation is quite different with lung cancer. When the diagnosis is made, no more than one quarter of patients have a disease that can be removed by surgery. Even when surgery is carried out and it seems that the cancer has been removed, only about one quarter of those patients are cured. Overall, less than 10 per cent of patients will be cured by surgery.Other means of treating lung cancer have been equally unsuccessful. Radiotherapy has been applied vigorously in a wide range of doses and with a wide range of schedules for the last fifty years. Although the treatments have become simpler and safer, and in many ways more sophisticated, very few patients are cured by radiotherapy alone. The introduction of drugs for the treatment of lung cancer in the 1960s gave rise to great hope for the group of patients with a sub-group of very dangerous cancers known as small-cell lung cancers. Combinations of drugs have proved capable of producing frequent remissions for this group of lung cancer patients. The disease shrinks readily away when the drugs are used and, during the 1970s and 1980s, intensive research was directed to using this effect and trying to turn it into lasting remissions and cures. Such efforts have, however, been met with disappointment. Patients with small-cell lung cancer can usually expect remissions as a result of these combination chemotherapies, but very few are cured.The scale of the epidemic of lung cancer is illustrated in Figure it. The disease started to increase in the 1920s and 1930s and achieved its present epidemic proportions during the 1950s and 1960s. The number of deaths due to lung cancer is however, beginning to show signs of a significant reduction. The graph shows the death rate against the number of cigarettes consumed; we must now accept that this indicates the clearest and most important explanation of this century’s lung cancer epidemic.There is an indisputable and strong link between lung cancer and smoking. In fact, almost all lung cancers are attributable to smoking and, if the smoking habit were dropped, lung cancer would revert to its former status as an infrequent diagnosis, of concern only to the individual patient and doctor. Instead, it remains one of the most overwhelming public-health issues facing the world as it moves towards the twenty-first century.*37\194\4*