SAN FRANCISCO – For years, 50 years old has been the age at which screening for colorectal cancer (CRC) began in the United States, but recently, one group lowered the starting age to 45 years.
pixologicstudio/Thinkstock
This move by the American Cancer Society in 2018 was made in reaction to reports of an increase in the incidence of CRC in younger adults.
However, other groups have stayed with the benchmark 50 years. This includes the U.S. Preventive Services Task Force and the National Comprehensive Cancer Network.
Should the age be lowered in view of the mounting reports of an increase in CRC in younger adults? Experts argued both for and against the move here at the 2020 Gastrointestinal Cancers Symposium.
“We’re having this debate because the health of more than 20 million Americans is in the balance,” commented David Weinberg, MD, MSc, chairman of the department of medicine at Fox Chase Cancer Center in Philadelphia. “This is not just an academic discussion.” If the screening age shifts to 5 years earlier, the impact nationally would be about 30,000 colorectal cancers and 11,000 deaths averted.
“It will take about 11 million additional colonoscopies ... and the overall bill would be $10 billion. That’s not a small number, but if the country has the resources and we want to do this, I would say we can,” argued Uri Ladabaum, MD, director of the gastrointestinal cancer prevention program and the clinical chief of the division of gastroenterology and hepatology at Stanford (Calif.) University.
Lower the age
Dr. Ladabaum argued in favor of lowering the age to 45 years to start screening. “In life, 60 may be the new 40, but for colorectal cancer screening, 45 is definitely the new 50,” he said. Anticipating arguments against such a move, he focused on several points.
First, the magnitude of the problem is certainly not small, he noted, pointing to a 2017 study showing that colorectal cancer rates have increased by 1%-2.4% annually since the mid-1980s in persons aged 20-39 years and by 0.5%-1.3% since the mid-1990s in adults aged 40-54 years (J Natl Cancer Inst. 2017;109:djw322). Rectal cancer incidence has been increasing even more rapidly, at a rate of about 3.2% annually during 1974-2013 in adults aged 20-29 years.
Overall, people who were born around 1990 and later have double the risk of colon cancer (incidence rate ratio, 2.40) and quadruple the risk of rectal cancer (IRR, 4.32) as compared with those born circa 1950.
“Thus, 45- to 49-year-olds are beginning to look like yesterday’s 50- to 54-year-olds used to be,” said Dr. Ladabaum.
One issue that has been raised is lead-time bias, with the burning question: Are the cancers found in adults in their 40s simply the same ones that would have eventually been detected in their 50s? Dr. Ladabaum argued that they are not, referencing a 2019 study showing that among persons aged 40 through 49 years, the disease was diagnosed at later stages (JAMA. 2019;321:1933-4).
For those aged 40- 49 years, there was a significant increase in incidence during 1995-2015. The proportion of distant cancers increased significantly (from 21.7% to 26.6%; P less than .001), and the authors of the study had noted that this increase of 4.9% could not be explained by a decrease in unstaged cases. “In the early ’90s and mid-’90s, we began to see an increase in all stages,” Dr. Ladabaum noted. “And the most important thing here is the distant cancers over time. They’ve gone up.” If the only explanation was lead time bias in people aged 40- 49 years, then a person screened and diagnosed with cancer at age 48 would have earlier-stage disease than if it had been found at age 51. “So is this all lead-time bias?” he said. “I think the answer is no.”
Next, Dr. Ladabaum tackled the issue of whether benefit/risk ratio of CRC screening is different among younger vs. older adults. This is difficult to tease out, he suggested, as the data are sparse and there were no controlled studies to date to address that. One study from Taiwan, which looked at the outcomes of fecal immunochemical testing (FIT), showed that in different age groups, the hazard ratio for detecting cancer in those with positive results is higher in younger people vs. older ones (J Clin Gastroenterol. 2016 Oct;50[9]:761-8).
“Indirect evidence shows that if we do a FIT test and it’s positive, it probably means something,” he said. “But is there something magical that at age 50 and older – that it becomes a screenable disease, and through age 49 it’s not screenable? I would say no. Biology is not like this.”
Finally, is it cost effective to start earlier? In a modeling projection published last summer by Dr. Ladabaum and colleagues, starting at 45 years would avert about four colorectal cancers and two colorectal cancer deaths per 1,000 people, and the cohort would gain approximately 14 quality-adjusted life years (Gastroenterology. 2019;157:137-48).
“The incremental cost per quality-adjusted life year gained is highly acceptable,” said Dr. Ladabaum. “This is well within the range of what’s considered cost-effective in the United States – under $35,000 for colonoscopy, and under $8,000 for fecal immunochemical tests.”
Therefore, the answer is yes, it is cost effective, he concluded.