Incidence of colorectal cancer spiked among adults in the United States between the ages of 49 and 50 years, the age when many have routine screening colonoscopies, based on data from a cross-sectional study of 165,160 patients.
“We would expect to see some degree of CRC incidence increase from 49 to 50 years of age owing to screening uptake and diagnosis of preexisting CRCs that may have been clinically undetected,” wrote Wesal H. Abualkhair, MD, of Tulane University, New Orleans, and colleagues.
In a study published in JAMA Network Open, the researchers reviewed data from the Surveillance, Epidemiology, and End Results (SEER) registries from 2000 to 2015 on colorectal cancer incidence in 1-year intervals for adults aged 30-60 years, focusing on the year between ages 49 and 50.
Overall, the incidence of colorectal cancer increased by 46.1% from 49 to 50 years of age, and 93% of these cases were invasive.
The increase in cancer rates occurred across geographical regions, sex, and race, and likely reflects the impact of screening rather than advancing age, the researchers said.
They also found a significant increase in 5-year relative survival (6.9% absolute increase, 10% relative increase) for the transition between 49 and 50 years of age; no other age transitions showed a significant change.
The findings were limited by several factors, including the lack of specific outcomes data and inability to determine the number of years that the cancers existed before diagnosis, the researchers said. However, the results were strengthened by the large study population and detailed yearly assessment.
“Our analysis of the transition from 49 to 50 years provides new, registry-based data regarding risk among individuals younger than 50 years, which can add to preexisting modeling studies to help inform decision-making on the age at which to initiate screening,” the researchers said.
The study did not receive outside funding. Lead author Dr. Abualkhair had no financial conflicts to disclose.
SOURCE: Abualkhair WH et al. JAMA Network Open. 2020 Jan 31. doi: 10.1001/jamanetworkopen.2019.20407.