CRC incidence spikes between ages 49 and 50 years
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A steep increase in incidence of colorectal cancer among patients aged between 49 and 50 years may suggest that many cases go undetected in younger patients before they reach routine, average-risk screening at age 50 years, according to data published in JAMA Network Open.
“Given the current debate over colorectal cancer screening at age 45 vs. 50, we felt it would be revealing to conduct an incidence rate analysis by yearly-age, as opposed to age range blocks (30-39, 40-49, etc.) as has been done in prior studies,” Jordan J. Karlitz, MD, director of the GI Hereditary Cancer and Genetics Program at Tulane University School of Medicine, told Healio Gastroenterology and Liver Disease. “To our knowledge, a yearly-age incidence rate analysis had not been performed in the past. This type of analysis would allow a more detailed assessment of the incidence rates of those approaching or at screening age. In particular, we were interested in the transition from age 49 to 50 as this is when average risk screening has historically been recommended.”
The investigators wrote that the observed incidence rates may underestimate the burden of CRC on individuals younger than 50 years, because screening is generally not done to detect preclinical cases of CRC.
Researchers conducted a cross-sectional study of CRC incidence rates using data from the SEER 18 registries from 2000 to 2015 in 1-year increments stratified by region, sex, race, disease stage and tumor location. They included individuals aged between 30 and 60 years.
In their analysis of 170,434 cases of CRC among 165,160 patients, Karlitz and colleagues found a 46.1% increase in CRC incidence from ages 49 (34.9 per 100,000 population; 95% CI, 34.1–35.8) to 50 years (51 per 100,000 population; 95% CI, 50–52.1). Of the 9,474 cases of CRC diagnosed in patients aged 50 years, 8,799 were invasive (92.9%).
The rate ratio increase in incidence between ages 49 and 50 years was higher than any earlier 1-year age transition (1.46; 95% CI, 1.43–1.51), and the steep increase was observed in all regions, men and women, black and white populations, and in colon and rectal cancers.
When they explored stages at which cancers were detected, Karlitz and colleagues identified an increase from 49 to 50 years in localized (75.9% increase) and regional cancers (30.3% increase).
Karlitz said the combined burden of CRC cases in patients aged 45 to 49 years may come close to the burden among patients in their 50s.
“Of course there is always going to be an undetected, preclinical cancer case burden in patients of any age, including those over age 50, which may be compounded by non-optimized CRC screening rates,” Karlitz said. “But we feel the revealing aspect of our study is that we assessed this preclinical burden in those approaching screening age, which is important given the ongoing debates on when screening should be initiated. We are hoping these data can contribute to the earlier screening debates.” – by Alex Young
Disclosure: Karlitz reports receiving personal fees from Exact Sciences and Myriad Genetics outside the published work and owning an equity position in Gastro Girl and GI OnDemand. Please see the full study for all other authors’ relevant financial disclosures.
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