Screening Colonoscopy May Benefit Elderly Patients

Caroline Helwick

June 01, 2011

June 1, 2011 (Chicago, Illinois) — Although routine colonoscopic screening for colorectal cancer (CRC) is not recommended in the elderly, studies presented here at Digestive Disease Week (DDW) 2011 lend some support to this practice.

Ann G. Zauber, MD, principal investigator of the National Colonoscopy Study and associate attending biostatistician at Memorial Sloan-Kettering Cancer Center, New York City, presented a model that simulated CRC screening in persons aged 75 years and older who had never been screened.

"People who have never been screened and are at average risk at age 75 should be offered colonoscopy until age 85, plus or minus a few years, depending on how risks and benefits are weighed," Dr. Zauber concluded, based on the findings.

In spite of decades of recommendations for CRC screening, a considerable number of elderly people in the United States have never been screened, she pointed out. In 2008, the United States Preventive Services Task Force (USPSTF) recommended that CRC screening begin at age 50 years and continue to age 75 years, and then be discontinued if there were consistent negative findings.

However, the average age of CRC diagnosis is 71 years, and 43% of CRC cases are diagnosed at age 75 years and older. In addition, 37% of persons aged 75 to 84 years have never had a colonoscopy, Dr. Zauber pointed out.

"Age in the mid-70s is where we are seeing a large number of cancers and cancers yet to come," she said. "The task force recommendations did not address the elderly population without prior screening. We suggest that it might be effective and cost-effective to offer colonoscopy to this group."

Using decision analysis based on microsimulation modeling, as used by the USPSTF in making its recommendations, Dr. Zauber and colleagues calculated the life-years gained (LYG) by screening various age groups. They compared this benefit with age-specific risks for serious adverse events associated with colonoscopy and polypectomy in the Medicare population. Their cost analysis included screening, diagnosis, treatment, and complication costs.

Less Benefit in Older Persons, but Benefits Still Demonstrable

"Screening beginning at age 50 certainly gives you the most bang for the buck, but we don't want to forget people who have never been screened by age 75 or so. We need to make sure we screen persons aged 75 to 80," Dr. Zauber told Medscape Medical News.

"Our analysis showed that LYG decreases sharply after age 75," she said. LYG per 1000 persons screened was approximately 150 at age 65 years, 100 at 75 years, 60 at 80 years, 20 at 80 years, and less than 5 at 90 years of age. In parallel, the number of colonoscopies required per LYG rose steadily with age.

Table. Summary of Outcomes per LYG With Colonoscopy

Age at Initiation of Screening (Years) Number of Colonoscopies per LYG Serious Gastrointestinal Complications per LYG Costs per LYG ($)
65 13 0.038 −3.637
80 24 0.122 −2601
83 30 0.172 −50
85 41 0.256 5050
89 114 0.843 46,278
90 161 1.24 75,325

Cost effectiveness and serious gastrointestinal and other adverse events per LYG were "quite acceptable" at age 75 years, Dr. Zauber stated, and "borderline acceptable" at age 85 years.

The cost-effectiveness analysis did not include biologics as part of treating CRC, "but if we did include these agents, there might be even more cost savings with screening of the elderly," she suggested.

Dr. Zauber said the results supplement those of the decision analysis in which she participated for the USPSTF.

"I was involved in the decision analysis for the 2008 recommendations. I informed the task force that we are now conducting this analysis, and they were pleased. We will present the data to them," she said.

Second DDW Study Supports Elderly Screening

In a second presentation at the session here at DDW 2011, Vishnu Naravadi, MD, showed data suggesting that the prevalence of colorectal neoplasia is high enough in persons aged 75 years and older, and the average life expectancy long enough (12 years), to "necessitate the need to consider screening in this age group."

Dr. Naravadi and colleagues conducted a retrospective chart review of patients undergoing colonoscopy at Mt. Sinai Hospital in Chicago, Illinois, between 2007 and 2010 and identified 96 persons screened at age 75 years and up. Exclusion criteria were history of previous colonoscopy, inflammatory bowel disease or colorectal neoplasia, and clinical indications for colonoscopy. Mean age of the subjects was 78 years, 28% had diabetes, and 22% had coronary artery disease as comorbidities.

The mean colonoscopy withdrawal time exceeded 6 minutes, and for 97% of patients the cecum was intubated. The adenoma detection rate among these elderly patients was 34%, including 50% among white patients, 32% among black patients, and 33% among Hispanic patients. Significant colorectal neoplasia was noted for 17%, 24%, and 11% of the patients, respectively. One patient (3%) had a CRC. No adverse events were noted as a result of the procedure, Dr. Naravadi reported.

Adenoma detection was greater in men (46%) than women (24%), as was the finding of significant neoplasia (23% vs 16%). Significant neoplasia was defined as an adenoma larger than 1 cm, polyps with villous histology, or the occurrence of 3 or more adenomatous polyps.

By location, most findings were in the proximal colon vs the distal colon (for CR neoplasia, 61% vs 39%; for adenomas, 59% vs 41%; for significant neoplasia, 61% vs 39%). The single case of CRC was located in the proximal colon.

"The higher prevalence of colorectal neoplasia in the proximal colon signifies the importance of complete colonoscopy, rather than sigmoidoscopy, especially in those aged 75 and above," Dr. Naravadi maintained.

Robert Bresalier, MD, professor of medicine at the University of Texas M.D. Anderson Cancer Center, Houston, commented on the findings for Medscape Medical News.

"These studies are coming from a growing awareness of the risk/benefit ratio in CRC screening. It makes sense to do this modeling, but on the other hand, it is only a model," he said.

"Certainly, one size does not fit all, and persons of a certain age are not all the same physiologically. That is why the task force guidelines did not recommend routine screening of older persons, but they do not say that screening these persons should not be done. They gave some buffer to deal with physiologic age," Dr. Bresalier continued.

"In the older age group who is healthy and who has never been screened, first-time screening may make some sense. But the modeling study also did not address the issue of what to do in the patient who was screened at age 68, had not significant neoplasia, and is now 75. Should we rescreen? For this group the answers are still not clear," he asserted.

Dr. Zauber, Dr. Naravadi, and Dr. Bresalier have disclosed no relevant financial relationships.

Digestive Disease Week (DDW) 2011: Abstracts 63 and 64. Presented May 7, 2011.

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