Should patients get screened for colorectal cancer at age 45? Experts weigh in

The American Cancer Society (ACS) made a qualified recommendation in its 2018 guidelines to initiate colorectal cancer (CRC) screening at age 45 years instead of 50 years. Experts weighed the pros and cons of this recommendation in a commentary published in Gastroenterology.

“The medical, research, and advocacy communities are united in the concern about the increasing incidence of young onset CRC,” wrote authors led by Peter S. Liang, MD, MPH, NYU Langone Health and VA New York Harbor Health Care System, New York, NY. “However, the routine recommendation of screening initiation at age 45 instead of 50 years, in the context of current epidemiologic, public health, and policy realities, may have several unfavorable and unintended consequences.”

Adding life-years

Initiating colonoscopy screening at age 45 years vs 50 years will yield 25 additional life-years gained per 1,000 people screened, according to an updated screening model commissioned by ACS. These additional life-years could be due to early detection of CRC in the 45- to 49-year-old age group, which accounts for 5% of total CRC cases. Additionally, this increase in life-years could be due to prevention of CRC in 50- to 60-year-olds due to earlier detection and removal of precancerous polyps.  

“Reducing young-onset CRC is highly desirable, because premature death at a younger age results in substantial loss of high-quality life-years and productivity,” the experts wrote.

The ACS recommendation to initiate screening at age 45 years could also enhance screening uptake in minorities, such as African Americans or Native Alaskans, who have higher CRC incidence and mortality. Furthermore, by starting to recommend CRC screening at age 45 years, patients aged 50 years and older would have received the message more frequently, and this could result in increased screening in patients aged ≥ 50 years.

Currently, the ACS recommendation differs from those of the US Preventive Services Task Force (USPSTF), the US Multi-Society Task Force (USMSTF), and the Centers for Disease Control and Prevention (CDC), which could send a mixed message to the public, thus eroding public confidence, the authors noted. Moreover, providers may choose to focus on screening patients aged between 45 and 49 years instead of older age groups—aged between 50 and 75 years—who are at higher risk.

The authors suggested that optimizing screening and follow-up in these older patients may be a better approach to reducing CRC burden among the entire population.

Health disparities and society costs

According to the authors, the fundamental causes theory predicts that individuals of lower socioeconomic status (SES) are less likely to benefit from new health interventions than are patients with more medical insight and money. Lower SES individuals are more likely to belong to racial/ethnic and geographic groups at elevated risk for CRC. By initiating screening at age 45, the expanded pool of patients may exacerbate health disparities.

The new ACS recommendation expands the screening pool by 21 million people aged between 45- and 49-years-old, resulting in an additional 810 colonoscopies per 1,000 patients and substantially compounding societal costs.

Predicted vs actual outcomes

Most of the observed increase in young-onset cancer occurs at the level of the distal colon and rectum. These cancers are better detected by less invasive tests. Further research is needed to determine the best screening test and initiation age for young-onset cancers.

“If screening at 45 years of age is universally implemented, then the opportunity to study the effectiveness of, and best strategies for screening in this population may be lost,” the authors wrote.

One final concern about the recommendation to initiate CRC screening at 45 years has to do with whether the model developed by the ACS to inform the new recommendation has limitations. In other words, the actual benefit of this recommendation may be less than expected.  

Summary

“Before embarking on a major change in screening policy, further research is needed to identify the underlying CRC risk factors in younger adults and the potential benefits of screening in this population,” concluded the experts.