The findings of a new study make a case for targeting colorectal cancer screening in older adults so that those who will benefit do undergo such testing, and those who will not benefit are not exposed to unnecessary burdens.

The study participants were 212 patients from four VA medical centers, aged 70 years and older. They were followed for 7 years after receiving a positive fecal occult blood test (FOBT). Christine Kistler, MD, MASc—who led the study while completing a geriatrics fellowship at the University of California, San Francisco, and the San Francisco VA Medical Center—and colleagues determined net burden or benefit from screening and follow-up according to each patient’s life expectancy, classified as follows:

  • best life expectancy (for patients aged 70-79 years and a Charlson-Deyo comorbidity index [CCI] of 0)
  • average life expectancy
  • worst life expectancy (aged 70-84 years + CCI ≥4, or 85 years or older and CCI ≥1).

Net burden could include never having received a follow-up colonoscopy, finding no evidence of cancer on follow-up colonoscopy, dying of causes other than colon cancer, or otherwise receiving no benefit from the positive FOBT result.

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A total of 34 significant adenomas and 6 cancers were found in the 118 (56%) of patients receiving follow-up colonoscopy after positive FOBT. Within that group, 12 (10%) experienced complications from colonoscopy or cancer treatment.

Among the 94 subjects who did not receive follow-up colonoscopy, 43 (46%) died of other causes within 5 years of FOBT, and three died of colorectal cancer within 5 years.

The investigators calculated that 26 of the 30 patients with worst life expectancy (87%) experienced a net burden from screening, as did 92 of 131 (70%) with average life expectancy and 35 of 51 (65%) with best life expectancy.

“Over a 7-year period, older adults with best life expectancy were less likely to experience a net burden from current screening and follow-up practices than are those with worst life expectancy,” concluded Kistler’s team in an online report published by Archives of Internal Medicine ( “The net burden could be decreased by better targeting FOBT screening and follow-up to healthy older adults.”