Posted by November 15th, 2005
There is general agreement that the benefits of beginning screening at age 50 for people of average risk of colorectal cancer outweigh its potential risks. However, it isn’t clear at what age risks no longer are balanced by benefits.
Whether or not screening will make a difference for an individual depends on age, other existing illnesses, and potential life expectancy. In addition, some older people may experience more complications during screening tests increasing their risk.
Researchers at the University of Washington in Seattle report an analysis of screening benefits in the elderly in the October 2005 issue of [*Gastroenterology*](http://www.gastrojournal.org/article/PIIS0016508505013910/abstract). Cynthia Ko and her team looked at men and women, aged 70 to 94 years of age with various health conditions and life expectancies. They determined the number of people it would be necessary to screen to prevent one colon cancer-related death and also the numbers necessary to encounter a complication for three different approaches to screening — annual fecal occult blood tests, flexible sigmoidoscopy every 5 years, or colonoscopy every 10 years.
For instance, one cancer-related death would be prevented by screening 42 healthy men aged 70â€“74 years with colonoscopy, 178 healthy women aged 70â€“74 years with fecal occult blood tests, 431 women aged 75â€“79 years in poor health with colonoscopy, or 945 men aged 80â€“84 years in average health with fecal occult blood tests. While colonoscopy had the greatest benefit, it also had the greatest risk of complications. However, at all ages and life expectancies, the potential reduction in mortality from screening outweighed the risk of colonoscopy-related death.
The study identified four groups of elderly people for whom screening with colonoscopy was likely to have more risk than benefit:
+ Women aged 70 to 79 years in poor health
+ Women aged 85 to 89 years in average health
+ Men aged 70 to 74 years in poor health
+ Men aged 90 to 94 years in good health
Dr. Cynthia Ko told [*Reuters Health*](http://today.reuters.com/news/newsArticle.aspx?type=healthNews&storyID=2005-11-15T183409Z_01_FLE566824_RTRUKOC_0_US-COLON-CANCER-SCREENING.xml&archived=False)
The decision to pursue screening should be individualized and should take into account a patient’s life expectancy, comorbidity, and preferences.
In an [accompanying editorial](http://www.gastrojournal.org/article/PIIS0016508505017506/fulltext) Carmen Lewis reminds readers that the study assumes information about life expectancy that may not be true for an individual and urges that information from the research be used to guide discussions between patients and their doctors in making screening decisions:
Ko and Sonneberg have provided important estimations helpful for individualized decision making for colorectal cancer screening in patients ages 70 and older. However, their findings are estimations based on average life expectancies of the US population. Physiciansâ€™ abilities to accurately estimate life expectancy for individual patients is poor and, at present, even calculated estimations are of questionable validity. Furthermore, patients may vary significantly in how they value the potential benefits from screening compared with the potential harms Therefore, this information should be used as an aid to help inform patients about the risks and benefits of colon cancer screening, and then with their physicians, patients can explore their personal values and make the decision that is right for them.