“Although it is suggested that some cancer screening tests have led to substantial increases in early-stage incidence with only marginal reductions in late-stage incidence (eg mammography), the association between temporal trends in colorectal cancer screening and its cumulative impact on colorectal cancer incidence is unknown,” Daniel X. Yang, of the Yale University School of Medicine, and colleagues, reported in Cancer.
To better understand the incidence data for colorectal cancer during the screening period from 1986 to 2010, the researchers examined data from the National Cancer Institute Cancer Trends Progress Report.
The percentage of adults aged 50 years and older who underwent screening for colorectal cancer increased from 34.8% to 66.1% from 1987 to 2010. During this period, the incidence of late-stage colorectal cancer decreased from 118 to 74 cases per 100,000 population (P<0.001). The incidence of early-stage colorectal cancer decreased from 77 to 67 cases per 100,000 population (P<0.001).
Over the past three decades in the United States, colorectal screening was associated with a reduction of about 550,000 cases of colorectal cancer, the researchers estimated.
“There has been a significant decline in the incidence of colorectal cancer in the United States, particularly for late-stage disease, during a time of increasing rates of screening,” wrote the researchers.