The Effect of Age and Chronic Illness on Life Expectancy After a Diagnosis of Colorectal Cancer: Implications for Screening
Gross CP, McAvay GJ, Krumholz HM, Paltiel AD, Bhasin D, Tinetti ME
Ann Intern Med. 2006;145:646-653
The number of screening colonoscopies in elderly US patients has increased dramatically since Medicare coverage for average-risk individuals was approved in 2001. The current guidelines, however, do not specify an age limit above which screening is not recommended. Colonoscopy in very elderly patients is associated with lower procedural completion rates, higher complication rates, and higher risk for inadequate bowel preparation. As such, some clinicians may have concerns with regard to recommending colorectal cancer (CRC) screening to extremely elderly patients. Furthermore, these elderly patients have shorter life expectancies, potentially limiting the benefits of screening procedures. In fact, a recent publication called into question the practice of screening patients older than 80 years of age. Perhaps more important than age is the potential impact of the presence of comorbid illnesses. The effect of life expectancy in these patients as a result of these diseases has not been incorporated into the guidelines that support the practice of CRC screening. To date, randomized trials have suggested that a change in mortality rate due to CRC between screened and unscreened persons does not become apparent until 5 years after screening.[2,3]
This retrospective cohort study by Gross and colleagues involved the use of the Surveillance, Epidemiology and End Results (SEER) program-Medicare database (using the base years of 1993-1999) for patients with a primary diagnosis of CRC. All patients were at least 67 years of age, which allowed for at least a 2-year database analysis of other coexistent diseases. Chronic diseases that had a demonstrated significant causal-related mortality were also identified. These included myocardial infarction, congestive heart failure, peripheral or cerebral vascular disease, chronic obstructive pulmonary disease, dementia, paralysis, diabetes, renal failure, liver disease, ulcers, AIDS, rheumatologic disease, hip fracture, and atrial fibrillation.
Patients were then assigned to 1 of 3 categories on the basis of the number of these coexistent conditions (0, 1-2, or ≥ 3). A total of 35,755 patients were included in the analysis. Approximately 40% of patients had no chronic conditions, 44% had 1-2, and 15% had 3 or more. The median length of follow-up was 4 years.
Life expectancy was strongly correlated with age, cancer stage at diagnosis, and the coexistent conditions. For example, among men with a diagnosis of stage I CRC, at age 67, life expectancy following the diagnosis decreased from 19.1 years (95% confidence interval [CI]: 17.8-20.5 years) for those with no chronic diseases, to 12.4 years (95% CI: 11.4-13.5 years) for those with 1-2 diseases, and to 7.6 years (95% CI: 6.1-9.4 years) for those with 3 or more concomitant diseases.
For those patients diagnosed with stage III disease, the association was less dramatic. A 67-year-old man with this stage of CRC had a life expectancy that ranged from 8.4 years when there were no chronic conditions to 4.6 years when there were 3 or more chronic diseases. For women, the life expectancies similarly ranged from 8.5 to 4.7 years.
By age 81, the life expectancies declined further. For stage I disease, the researchers reported:
Life expectancies of 10.3 (95% CI: 9.2-11.9) and 13.8 (95% CI: 12.3-15.3) years for men and women with no chronic conditions, respectively;
Expected remaining lifespan of 6.7 (95% CI: 6.3-7.3) and 8.2 years (95% CI: 7.7-8.8) for men and women, respectively, with 1-2 chronic diseases; and
Life expectancies of 4.3 (95% CI: 3.9-4.8) and 4.9 years (95% CI: 4.5-5.4) for men and women, respectively, with 3 or more chronic diseases.
Despite a higher prevalence of neoplasia in elderly patients, the mean extension in life expectancy was much lower in the group aged 80 years or older than in the 50- to 54-year-old group (0.13 vs 0.85 years).
The early detection of CRC is associated with a dramatic reduction in disease-related mortality. Recognizably, the incidence of CRC rises sharply with advancing age. Most patients in fact are older than 65 years at the time of presentation with their disease. The main intent of colonoscopic screening is the detection and removal of a precancerous adenoma. It is understood that the lag time before this precancerous lesion can develop into cancer and cause death is usually lengthy (10-15 years). This fact suggests that the potential benefit of colonoscopic screening in patients with significant comorbid diseases may be smaller than what can be expected for other types of cancer screening because these patients are more likely to die of "natural" causes before the adenoma develops into cancer. Therefore, even though the prevalence of colonic neoplasia increases with age, screening colonoscopy in these older patients with comorbid conditions results in smaller gains in life expectancy compared with younger patients, even when adjusted for life expectancy.
Overall, however, these data suggest that the benefit of screening colonoscopy in older and sicker patients may be smaller than what is commonly believed. This should help individual patients and clinicians decide whether screening colonoscopy should be performed and help avoid its use in patients who are unlikely to benefit substantively. Future work should explore how to integrate specific conditions and combinations of conditions into more precise estimates of life expectancy. Although it was not the intent of this study, it would seem a logical extension of this conclusion to apply to the issue of when to discontinue colon polyp surveillance in these patients. However, any decision to limit follow-up colonoscopy should be made with full disclosure to patients and their agreement with the rationale and assessment of overall risks.
Medscape Gastroenterology. 2006;8(2) © 2006 Medscape
Cite this: To What Degree Does Life Expectancy Vary With Respect to Age or Comorbid Chronic Illness After Diagnosis of Early-Stage Colorectal Cancer? - Medscape - Dec 14, 2006.