Secular changes in colorectal cancer incidence by subsite, stage at diagnosis, and race/ethnicity, 1992-2001

BACKGROUND. Cancers of the colon and rectum are the third most common malignancy among males and females in the United States, although incidence and mortality have declined in recent years. We evaluated recent trends in colorectal cancer incidence in the United States by subsite and stage at diagnosis. METHODS. Data for this analysis included all cases of colorectal cancer diagnosed between 1992 and 2001 and reported to the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program. Incidence rates were stratified by gender, race/ethnicity; anatomic subsite, stage at diagnosis, and SEER registry. Trends in incidence over time were measured using the estimated annual percentage change. RESULTS. The study population included 95,539 males and 93,329 females with colorectal cancer. For all 12 SEER registries combined, incidence declined between 1992 and 2001 by 1.2% per year among males and 0.7% per year (not statistically significant) among females. Rates for non-Hispanic whites declined by an average of 1.3% per year for males and 0.6% per year for females. Overall rates for black, Asian/Pacific Islander, and Hispanic males and females did not change significantly except for a 0.8% decline among Asian/Pacific Islander males. Declines in rates among males and females were most pronounced for tumors of the sigmoid colon. CONCLUSIONS. Colorectal cancer rates decreased in the United States during the 1990s. Decreases were most pronounced among males, among non-Hispanic whites, and for tumors of the sigmoid colon. These reductions are probably due to the increased use of screening.