United States lung carcinoma incidence trends: declining for most histologic types among males, increasing among females.

BACKGROUND

Lung carcinoma is now the most frequently diagnosed major cancer in the world and is also the most common cause of cancer deaths in males and females in the United States and worldwide. Based on trends in cigarette smoking and on analysis of lung cancer rates by birth cohort, it was predicted that a decline would occur in age-adjusted lung cancer rates, initially in males, and approximately 10 years later in females. We evaluated age-adjusted lung cancer incidence rates for changes in trends by race, sex and histologic type to determine if and when rates may have started declining.

METHODS

We analyzed population-based incidence data from the National Cancer Institute's Third National Cancer Survey conducted between 1969 and 1971 and from the Surveillance, Epidemiology and End-results (SEER) program conducted between 1974 and 1991. Age-adjusted rates were plotted by time period using a logarithmic scale for the ordinate. We used regression methods for grouped time-to-response data to fit a model to the disease rate for age, and calendar year to estimate the calendar year of maximum disease rate.

RESULTS

During this period, the overall age-adjusted lung cancer incidence rate rose from 37.8 to 68.2 per 100,000. Lung cancer rates in both white and black males climaxed around 1984 and declined subsequently. Furthermore, among white and black males, the rates of squamous cell carcinoma, small cell carcinoma, and large cell carcinoma declined after peaks in 1981 and 1982, 1986 and 1987, and 1986 and 1988, respectively. The rates for adenocarcinoma in black males peaked in 1987 whereas the rates in white males appeared to have plateaued between 1989 and 1991. Total lung cancer rates in males exceeded those in females, with rates in black males exceeding rates in white males. Age-adjusted lung carcinoma rates among white and black females continued to increase for all histologic types with the exception of large cell carcinoma among whites, bronchioloalveolar carcinoma among whites and blacks, and adenosquamous carcinoma among blacks.

CONCLUSIONS

The cumulative effect of these trends has resulted in a plateau of total lung carcinoma incidence in all persons combined, and a decline might be expected soon, as has already been observed among males. Most of these changes reflect past cigarette smoking patterns. Demonstration of declines and tapering increases among several population subgroups suggests impending reductions in the incidence and mortality rate for this highly fatal cancer.