Changing concepts in the management of patients with lung cancer

T he incidence of lung cancer has increased dramatically this century and, today, lung cancer represents the most common malignant disease in the industrialized world. Initially, the increase was most pronounced in urbanized men. However, in the last decade, the increasing incidence in men has levelled off in the United States and in some Western European countries, while the incidence of lung cancer in women continues to rise sharply. Similarly, a dramatic increase in lung cancer has been observed in recent years in developing countries. 1 These increases are most likely due to environmental factors, that is, inhaled carcinogens, mainly tobacco smoke. Efforts to reduce the future incidence of lung cancer by changing the smoking habits of new generations have been undertaken on national and international levels. In spite of the apparent success of these programmes in some countries, for example, Sweden and Finland, lung cancer will remain a common malignant disease worldwide for many decades. The number of publications on lung cancer, especially reports of therapeutic studies, also has increased in the last decade; generally, these have projected moderate optimism. This attitude is based primarily on the improved results that have been obtained by the use of combination chemotherapy in the treatment of small-cell lung cancer, which is now established as a specific disease entity with the features of a systemic disease. Although the three other major common histological types of lung cancer epidermoid carcinoma, adenocarcinoma and large-cell carcinoma correspond to several disease entities, they usually are termed collectively as "non-smallcell lung cancer". The purpose of the present broad review of the recent literature on lung cancer is both to present guide-lines for the management of the disease and to identify the future directions of therapy. We will endeavour to focus on areas where concepts are changing. If the WHO histopathological subclassification is employed,' more than 90010 of all malignant lung cancers fall into four types: epidermoid carcinomas (WHO-I, 35010); small-cell carcinomas (WHO-II, 30010); adenocarcinomas (WHO-III, 25010); and large-cell carcinomas (WHO-IV, 10010). The fifth most-common (5070) lung cancer is mesothelioma. The crude relative distribution of the various cell types that is given in parentheses varies from country to country. In general, there has been a tendency to observe an increase in the incidence of adenocarcinomas with a concomitant decrease in other cell types. The reasons for this are uncertain and the changes only partly can be explained by changes in the WHO classification which have resulted in an increase in the number of lung cancers that are classified as adenocarcinomas, with a similar decline in the number that are classified as large-cell carcinomas.' The biological and nosographical characteristics of the different types vary considerably, and so does their therapeutic management. Small-cell lung cancers are by far the most chemosensitive and normally have metastasized at the time of diagnosis; accordingly, systemic combination chemotherapy is the main mode of therapy, while local treatment modalities (that is, surgery and radiotherapy) are of lesser importance. In contrast, surgery especially is the corner-