Changing trends in incidence of lung cancer by histologic type in Scotland.

Lung cancer is a major public health concern worldwide. Our study aims to examine trends in incidence of lung cancer in Scotland during 1959-97 and by histologic type for 1975-97. In Scotland, lung cancer is the most commonly diagnosed cancer in men and is the second most commonly diagnosed cancer in women. Due to poor survival rates, trends in incidence and mortality display similar patterns. Within the United States and many parts of Europe, falls in the incidence of squamous cell carcinoma have occurred whilst the incidence of adenocarcinoma has increased. Data were extracted from the Scottish Cancer Registry. Trends in incidence were examined by standardising rates to the World Standard Population. Age-specific rates were examined by year of diagnosis and mid year of birth. In Scotland the incidence of lung cancer in men has fallen since the late 1970s, whereas incidence in women has continued to increase. Incidence rates of adenocarcinoma have increased over time but squamous cell carcinoma remains the predominant type of lung cancer in Scotland. The quality of lung cancer registration data has improved over time, although a large proportion of lung cancers (>20%) are not microscopically verified. Changes in histologic types are unlikely to be solely due to diagnostic advances. Rates of adenocarcinoma have increased steadily over time, and this may be due to changes in cigarette design during the 1950s.