A recent clinical guideline change from The American Cancer Society includes the recommendation for earlier initiation of colorectal cancer (CRC) screening, at age 45 instead of 50. “Lowering the screening initiation age is potentially the most impactful change to guidelines in recent decades,” says Uri Ladabaum, MD, MS. “It makes over 20 million additional Americans eligible for screening. When the recommendation was published, it spurred intense debate about the pros and cons and potential impact, including the implications for resource allocation and economic consequences.”


Answering the Big Questions

For a study published in Gastroenterology, Dr. Ladabaum and colleagues sought to estimate the cost effectiveness and national effects of adopting this new recommendation by answering three essential questions:

  1. Is it cost-effective to start CRC screening at age 45, given the increasing CRC risk in younger persons?
  2. What are the potential trade-offs in how resources are used? That is, what can a given number of colonoscopies achieve by starting at age 45 versus applying them to screen currently unscreened older people?
  3. What are the potential clinical, economic, and resource demand consequences at a national level?

Using a validated Markov model, the study team compared screening strategies and alternative resource allocations, basing national projections on screening participations rates by age and census data.

The researchers estimate that initiating screening colonoscopy at age 45 instead of 50 in 1,000 persons could avoid four CRC cases and two CRC-related deaths, gain 14 quality-adjusted life years (QALYs), cost about $34,000 per QALY gained, and require 758 additional colonoscopies. These additional colonoscopies could instead be used to screen 231 currently unscreened 55-year-old individuals or 342 currently unscreened 65-year-old people, through age 75, suggest Dr. Ladabaum and colleagues (Table). They also estimated that such alternatives could avert 13-14 CRC cases and six to seven CRC-related mortalities, while gaining 27-28 discounted QALYs and saving $163,700 to$445,800. By improving colonoscopy completion rates following abnormal fecal immunochemical tests, even greater benefits and savings could be achieved, the researchers suggested. They estimate that initiating fecal immunochemical testing at age 45 instead of 50 would cost $7,700/QALY gained.

Overall, the study team predicted that shifting the current screening age to 45 could avert nearly 30,000 CRC cases and more than 11,000 CRC-related deaths over the next 5 years, but at a cost of 10.7 million additional colonoscopies and an incremental $10.4 billion. On the other hand, they estimate, that improving screening rates to 80% in those aged 50 to 75 could avoid nearly three-fold more CRC-related deaths at one-third the incremental cost.

“Starting screening at 45 is likely to be cost-effective by traditional standards,” says Dr. Ladabaum. “However, if we can’t screen younger people AND improve in our screening rates for older people, then the benefits would be greater by improving screening rates in older people.” Dr. Ladabaum adds that he would like their findings to be a call to action to try to do both: improve screening rates in older persons and underserved populations, while also lowering the screening age.


Looking Ahead

In sensitivity analyses focusing on actual levels of CRC risk, Dr. Ladabaum and colleagues estimated that screening 45 year-olds who are at substantially lower CRC risk would be relatively costly. While physicians can try to guess who should be screened among healthy patients, or try to predict this using models, such guesses and predictions are not currently reliable, resulting in low confidence in whom it is reasonable to delay screening.

“I would like to see evidence that screening younger people is finding relevant polyps and early cancers, even if we can’t prove in a randomized study that it is decreasing risk of CRC-related death,” says Dr. Ladabaum. “There are unmet needs in screening all screen-eligible people. Establishing screening programs to accomplish this across the country would have a profound public health impact.”