Lung cancer is the second leading cancer diagnosis and the leading cause of cancer deaths in the United States, yet new data show black Americans and southerners are diagnosed at an even more alarming rate.
The Centers for Disease and Control reported in its weekly Morbidity and Mortality Weekly Report, dated Nov. 12, that annual incidence of lung cancer among blacks is 76.1 per 100,000, which is higher than the national incidence of 69.3 per 100,000. Whites were the second leading group with an incidence of 69.7 per 100,000, followed by American Indian/Alaska Natives (48.4). Hispanics fared better than did non-Hispanics, however, with an incidence of 37.3 per 100,000 vs. 71.9 among non-Hispanics.
In the South, the incidence of lung cancer was 76.0 per 100,000, also surpassing national numbers. Not only did white southerners have the highest incidence of lung cancer in the South (76.3), but among all whites in the United States as well (67.7).
According to the CDC, geographic location played a role in lung cancer incidence, and the agency noted that this report is the first to analyze lung cancer incidence among racial/ethnic groups by U.S. census region. The highest lung cancer incidences for blacks, Hispanics, and Asian/Pacific Islanders in the entire country were reported in the Midwest. There, blacks had a lung cancer incidence of 88.9 per 100,000, while Midwest Hispanics and Asian/Pacific Islanders had incidences of 40.6 and 64.2, respectively. People living in western states had the lowest lung cancer incidence in the nation with 58.8 per 100,000. Among Asian/Pacific Islanders, the highest lung cancer incidence was in the West with 42.5 per 100,000. All the incidence data reported were statistically significant, the CDC said.
The data came from a number of sources including the CDC’s National Program of Cancer Registries and the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program for the period 1998-2006. These combined data reflected new lung cancer cases "representing approximately 80% of the U.S. population," the report said.
The analysis included only cancer cases with the primary site of lung or bronchus, according to the World Health Organization’s International Classification of Diseases for Oncology, Third Edition.
Gender and age also were factors in incidence rates. Lung cancer incidence was higher in men than in women (88.2 vs. 55.4). Among persons aged 70-79 years, the incidence of lung cancer "peaked" at 426.7 per 100,000 and gradually declined with younger age. A similar age pattern persisted within racial and ethnic categories, the CDC said. In the 70-79 age group, a flip occurred – whites surpassed blacks with an incidence of 432.9 per 100,000, compared with blacks in the same age group (422.7). In every other younger age group, blacks had a higher lung cancer incidence.
"Racial/ethnic disparities in lung cancer incidence are associated with multiple factors, including differences in smoking prevalence, metabolism of tobacco smoke products, susceptibility to tobacco-induced lung cancer, and socioeconomic status. Blacks are more susceptible to smoking-induced lung cancer and have less access to health care services compared with whites. These factors might contribute to the higher lung cancer incidence in the black population," the report said.
The CDC noted that lung cancer also is caused by environmental exposures. "Radon, for example, is a naturally occurring, colorless, odorless gas that can become trapped in buildings; it is the second leading cause of lung cancer overall, and the leading cause of lung cancer in nonsmokers."
Four limitations were included in the report:
United States Cancer Statistics data only included 80% of the entire U.S. population and "might not accurately represent the whole U.S. population." Also, the national estimates of lung cancer incidence might be underreported because "many of the states that did not meet data-quality standards are in the South, the region with the highest smoking prevalence," the CDC said.
Information about smoking status is not available in the cancer registry data.
Racial/ethnic data in registries generally are of varying quality for American Indians/Alaska Natives and Hispanics.
The distribution of lung cancer histologic types was not considered in this analysis. "Although racial differences in histology have been shown in previous studies, unpublished analyses by CDC show little variation in lung cancer histology by region or race/ethnicity," the CDC said.
"Antismoking initiatives and efforts to reduce exposure to environmental carcinogens (e.g., radon and secondhand smoke) should be implemented to reduce the toll of lung cancer among all populations, especially targeting those at risk," the CDC concluded.