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How Do Age and Comorbidity Affect the Likelihood of Being Screened for Colorectal Cancer?
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What is the problem and what is known about it so far?
The purpose of screening tests is to detect disease when it has not yet caused harm. For example, cancer of the large bowel (colon cancer) is detectable well before it acquires the ability to invade the rest of the body. Removal of the cancer at an early stage greatly reduces the likelihood that the patient will die of colon cancer. However, this benefit of screening does not occur immediately. It often takes many years between when cancer could be first detected by screening and when it would have grown large enough to cause symptoms or cause the patient's death. During this period, the patient feels the same as if the cancer had not been removed. If a person who is treated for a small tumor detected by screening dies before the cancer would have caused symptoms if it had not been removed, they have not benefited from screening. As people get older and develop serious diseases, they become less likely to live long enough to benefit from early detection and treatment of cancer, and they are more likely to experience complications from tests and treatments. Therefore, most doctors agree that cutting down or stopping screening tests is a good idea when a person has only a few years to live.
Why did the researchers do this particular study?
To see whether doctors caring for veterans were less likely to do a screening test for colon cancer in patients with a limited life span.
Who was studied?
27 068 veterans who were at least 70 years of age, eligible for colon cancer screening, and seen in a Veterans Administration Health Care System clinic.
How was the study done?
The researchers checked each patient's Veterans Affairs and Medicare claims records to see how many serious chronic diseases he or she had, and then they measured how often these patients got a screening test for colon cancer.
What did the researchers find?
Somewhat fewer older, sicker patients (those with a 5-year death rate of 55%) were screened than younger, healthier patients (whose 5-year death rate was only 19%). However, the difference in screening rates between the sickest patients and the healthiest patients was quite small. For example, 41% of the oldest, sickest group got screening, whereas 47% of the healthiest group got screening.
What were the limitations of the study?
Tests for colon cancer can be used for screening (testing in people with no symptoms of disease) or diagnosis (testing in patients with symptoms of the disease). The researchers could not be sure why each patient received a test (screening or diagnosis).
What are the implications of the study?
Colon cancer screening in older patients could be improved. Part of the problem is a failure to screen healthy older people who are likely to live many years and may benefit from successful screening. The other part of the problem is screening people who have little or nothing to gain from early detection of colon cancer because they are very likely to die before they could benefit.
Article and Author Information
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The summary below is from the full report titled “Impact of Age and Comorbidity on Colorectal Cancer Screening Among Older Veterans.” It is in the 7 April 2009 issue of Annals of Internal Medicine (volume 150, pages 465-473). The authors are L.C. Walter, K. Lindquist, S. Nugent, T. Schult, S.J. Lee, M.A. Casadei, and M.R. Partin.
