A study of Medicare patients suggests that colonoscopy screenings for colorectal cancer are not as beneficial for patients age 75 and higher—the study also suggests that colonoscopy screenings carry a greater risk of side effects at this age. The findings highlight a potential gap in screening guidelines as well. The guidelines recommend colonoscopy screenings for older adults between ages 50 and 75, though Medicare reimburses such screenings without an upper age limit. This study was in part an attempt to see if there was any benefit to this approach.
In Brief: Cancer Screening
Screening is a type of preventative or proactive approach where an asymptomatic and average-risk population is checked for a specific disease. Since a scan has the risk of producing a false positive—and the procedure itself can have side effects—there are a lot of risk-benefit calculations that go into determining how often screenings should be done and at what age they should start and stop. The details about specific screening programs are subjects of debate, and cancer screening is even more controversial—just look at the furor that pops up whenever breast cancer screening recommendations are tweaked.
The study looked at 1,355,692 Medicare beneficiaries between ages 70 and 79 who had an average risk of developing colorectal cancer. These patients were divided into a 70–74 group and a 75–79 group, and were tracked over an 8-year period. Their use of screening colonoscopies, risk of colorectal cancer diagnoses, and any adverse events within 30 days of the screening were measured. The following findings were made:
- In the 70–74 group, the colorectal cancer risk was 2.19% in those screened and 2.62% in those not screened
- In the 75-79 group, the colorectal cancer risk was 2.84% in those screened and 2.97% in those not screened
- Among the 70–74 group, the adverse event rate was 5.6 events per 1000 individuals
- Among the 75–79 group, the adverse event rate was 10.3 events per 1000 individuals
- The outcomes of the colorectal cancer cases were not available
The lack of information about the outcome of the cancer cases is important, since it goes to the heart of why these colonoscopies are performed. Basically, screening can detect cancer earlier than it would be if it were discovered later, but this doesn’t necessarily mean it results in people living longer. If earlier detection and treatment doesn’t affect the rate in which people are dying from the cancer, then there is limited benefit from screening.
Having said that, the findings suggest those aged 70–74 can see some modest benefit from colonoscopy screenings, and that this benefit shrinks in 75–79 group. A colonoscopy is not a simple procedure, either, and requires a bowel cleanse and possible sedation. This can be hard on the system, which might explain why the patients in the 75–79 group had an almost doubled rate of adverse events.
It is also worth pointing out that these patients were all relatively healthy, which makes them the ideal candidates for preventative screening. Any benefit of screening would be reduced in people who have health problems that lower their life expectancy. If you’re likely to die of some other cause before your cancer starts getting serious, then early detection isn’t as valuable.
The study suggests that there is a modest benefit for healthy people aged 70–74 who get colorectal cancer-screening colonoscopies. Among those aged 75–79, the benefit is slight, but there is also a higher (though still small) rate of adverse events. It is not known how the screenings in the study affected the ultimate patient outcomes.
Garcia-Albeniz, X., et. al., “Effectiveness of Screening Colonoscopy to Prevent Colorectal Cancer Among Medicare Beneficiaries Aged 70 to 79 Years,” Annals of Internal Medicine, 2016; 10.7326/M16-0758.