Although there is no age cutoff for screening colonoscopy, its use in older patients is associated with lower procedural completion rates, higher complication rates, and inadequate bowel preparations. In addition to the inconvenience to the older population, colonoscopy also could have reduced benefits because it may not lead to improved life expectancy. Lin and associates compared life expectancy benefits from colonoscopy in younger and older persons.

In the study, asymptomatic patients undergoing colonoscopic screening were grouped into three age categories (50 to 54, 75 to 79, and 80 years and older). Outcomes included prevalence of neoplasia, advanced neoplasia (i.e., adenomas with more than 25 percent villous features or size larger than 1 cm), high-grade dysplastic lesions, and frank colorectal cancer. Further outcomes included mean extension of life expectancy, adjusted mean life expectancy extension, percentage of patients benefiting from colonoscopy, and number of colonoscopies per year of life saved.

A total of 1,244 patients underwent colonoscopy without complications. There were 488 men and 546 women in the 50-to-54 years age group, 69 men and 78 women in the 75-to-79 years age group, and 33 men and 30 women in the 80 years and older group. The prevalence of neoplasia was 3.2 percent in the youngest group compared with 14 percent in the oldest group, with an overall higher prevalence in men. Mean extension of life expectancy was 6.5-fold higher in the youngest group compared with the oldest group (0.85 year vs. 0.13 year, respectively). Only 1.18 colonoscopies were needed per year of life saved in the youngest group compared with 5.77 in the 75-to-79 group and 7.95 in the oldest group. Six percent of the youngest group benefited from colonoscopy compared with 12.2 percent in the 75-to-79 group and 15.9 percent in the oldest group, a finding that is explained by the increase in prevalence of colon cancer with advancing age (see accompanying table). Calculations estimating polyp lag time (i.e., the time span from polyp detection to development of colon cancer) and polyp progression probability also showed that screening was more worthwhile in younger patients.

Colon cancer screening is unique because when lesions are encountered during screening, they are removed. It takes a long time for polyps to become cancerous and, in spite of the higher prevalence of colon cancer in older patients, the benefit in life expectancy is much smaller for very old patients than for those who are younger.

The authors conclude that given the inconveniences and potential complications of screening, this information suggests that older patients and their doctors should make the decision to undergo colonoscopy on a case-by-case basis.