Early-onset colorectal cancer increases sharply between ages 49 and 50, study finds

Incidence of invasive early-stage colorectal cancer may increase markedly between ages 49 and 50 years, indicating that existing registries may underestimate disease burden in younger versus older patients, according to a recent study.

Researchers used data from the Surveillance, Epidemiology, and End Results (SEER) 18 registries to perform a cross-sectional study of colorectal cancer incidence rates from Jan. 1, 2000, to Dec. 31, 2015, in one-year age increments from ages 30 to 60 years. Rates were also stratified by U.S. region, sex, race, disease stage, and tumor location. The objective of the study was to examine the preclinical burden of colorectal cancer and to focus on the transition from age 49 years to age 50 years. The results were published Jan. 31 by JAMA Network Open.

Overall, 170,434 cases of colorectal cancer among 165,160 patients were analyzed. A total of 92,247 patients (55.9%) were men, and 75.4% were white. The mean age was 51.6 years. The researchers found that the incidence of colorectal cancer in the SEER 18 registries from age 49 years to age 50 years increased by 46.1%, from 34.9 (95% CI, 34.1 to 35.8) to 51.0 (95% CI, 50.0 to 52.1) per 100,000 population. Steep increases in colorectal cancer rates from age 49 years to age 50 years were seen in all U.S. regions, in men and women, in white and black patients, and in colon cancer and rectal cancer. The increase in rate ratio incidence in the SEER 18 registries (1.46; 95% CI, 1.42 to 1.51) was significantly higher from 49 to 50 years of age than for other, earlier one-year transitions. From ages 49 to 50 years, steep increases were seen in the SEER 18 registries for both local and regional colorectal cancer (75.9% and 30.3%, respectively). Overall, a large majority of the colorectal cancer cases diagnosed from 2000 to 2015 in patients 50 years of age in the SEER 18 registries were invasive (8,799 of 9,474 [92.9%]).

The authors noted that the SEER 18 registries represent 28% of the U.S. population and may not be generalizable to the whole country, among other limitations. They concluded that there is a steep increase in incidence of invasive colorectal cancer from age 49 to age 50 years, indicating a high burden of preclinical cases that went undetected at younger ages but were diagnosed when patients reached age 50 and were screened for the first time.

“These cancers were not reflected in observed SEER rates among individuals younger than 50 years; therefore, relying on SEER incidence rates among individuals aged 45 to 49 years alone to estimate potential outcomes of earlier screening at 45 years may underestimate the number of [colorectal cancer cases] that can be prevented or diagnosed at earlier stages,” the authors wrote. They called for further studies to determine the proportion of colorectal cancer cases detected by screening versus diagnostic testing at age 50 years, the incidence rate increase at age 45 years with earlier screening, and the cost benefit of earlier screening, among other factors.