Racial Disparities in the Incidence of Lung Cancer: The Savannah River Region Health Information System Cancer Registry, 1991-95

Brief communication 23 RACIAL DISPARITIES IN THE INCIDENCE OF LUNG CANCER: THE SAVANNAH RIVER REGION HEALTH INFORMATION SYSTEM CANCER REGISTRY, 1991-95 Lung cancer is the most common cancer in both men and women in the United States.1 Lung cancer incidence differs by race, with higher rates in black men than in white men.1,2 In recent years, the incidence of lung cancer has decreased in men but continues to increase in women.1,3 The histological distribution of lung cancer has changed with a decrease in squamous cell carcinoma and an increase in adenocarcinoma and small cell carcinoma.2,4"8 The U.S. Surveillance, Epidemiology and End Results (SEER) program reports lung cancer incidence by age, sex, race, and histological type.2,4 The SEER registry reports cancer incidence in racially diverse populations and has reported cancer incidence rates by race and ethnicity.9 Racial disparities in cancer incidence have been reported from urban areas, but there have been few reports of racial disparities in lung cancer in rural areas.10,11 The majority of the black populations included in the SEER registry reside in urban areas. The SEER cancer rates in black men and women in rural areas are derived largely from 10 rural counties in Georgia with a population of approximately 100,000 persons. The Savannah River Regional Health Information System (SRRHIS) is a cancer registry that covers a population of more than 1 million who reside in 22 South Carolina and Georgia counties adjacent to the Savannah River. These counties are predominantly rural, and 38 percent of the population is black. This study describes the incidence of lung cancer in 1991-95 by age, sex, race, and histology in these counties and contrasts racial disparities in lung cancer in these counties with reports from the SEER registry. Method The SRRHIS is a joint project of the Medical University of South Carolina in Charleston, South Carolina, and Emory University in Atlanta, Georgia. The purpose of the SRRHIS cancer registry was to identify all residents of the 22 counties adjacent to the Savannah River who were diagnosed with cancer from 1991 to 1995. Patients residing in any of the 20 SRRHIS counties from 1991 through 1995 who were diagnosed with cancer of the lung or bronchus were selected for this Received September 27,2001; revised February 14,2002; accepted April 9,2002. Journal of Health Care for the Poor and Underserved · Vol. 14,No. 1 · 2003 DOI: 10.1177/1049208902238821 24 Incidence of Lung Cancer study. Cancers were selected based on classification codes C340-C349 from the second edition of the International Classification of Diseases for Oncology (ICD-O2 ).12 Only primary cancers of the lung or bronchus were included in the analysis . Tumors were classified into one of five histological groups based on ICD-O histology codes, identical to the groups used in a recent study of national lung cancer incidence:2 adenocarcinoma, small cell carcinoma, large cell carcinoma, squamous cell carcinoma, and other. Incidence rates for lung cancer and 95 percent confidence intervals were calculated assuming a Poisson distribution for calculation of standard errors using the Statistical Analysis System (SAS).13 Age-adjusted rates were calculated for white men, white women, black men, black women, all men, and all women. Separate rates for other minorities were not reported, as the 1995 census projections of the population of the SRRHIS counties show that 97 percent of the region is either white (59 percent) or black (38 percent). Rates reported for the total population include all race and sex groups. AU rates were age adjusted and sex adjusted to the U.S. 1970 population, when appropriate, using the direct method of standardization. Incidence rates were also calculated for each of the histological types within the four race and sex groups. Disparities in lung cancer incidence by race were estimated by calculating the incidence rate ratio for the incidence of lung cancer in black men compared with white men and the incidence rate ratio for lung cancer in black women compared with white women. The incidence rate ratio calculations use Poisson regressions with maximum likelihood estimation and were performed using PROC GENMOD in SAS. Separate analyses...