Time trend and geographic patterns of lung adenocarcinoma in the United States, 1973-2002.

Objective: To find the major factor explaining the substantial increase in incidence of adenocarcinoma of the lung (ADL), we observed its temporal trend, distributions in geographic areas and populations, and compared them with the distributions of air pollution and low-tar cigarette consumption in time, place, and populations.

Methods: The temporal and spatial patterns of ADL were compared with the level of nitrogen oxides (NO(x)) emissions as well as the use of low-tar cigarettes.

Results: Similar increasing trends followed by declining trends were seen in emission levels of NO(x) and ADL incidence rates. These trends peak about 20 years earlier for NO(x) levels than for ADL incidence. Incidence rates of ADL in high NO(x) emission areas were substantially higher than those in low NO(x) emission areas. Incidence rates of ADL in Black males are about 50% higher than in White males and can be explained by the differences in air quality related to residence site and size.

Conclusions: The descriptive epidemiologic data help generate the hypothesis that long-term exposure to low-dose NO(x) may play a major role in causing steep increases in past ADL incidence rates. There is an urgent need to conduct further studies to determine whether the association is a causal relationship between long-term, low-dose exposure to NO(x) and ADL.