November 15, 2005

Colon cancer screening of little value for some

By Will Boggs, MD

NEW YORK (Reuters Health) - The risks of colorectal cancer
screening may outweigh the benefits for some patients aged 70
years and older, a group of doctors warn in the journal

"Colorectal cancer screening has risks as well as
benefits," Dr. Cynthia W. Ko from the University of Washington,
Seattle, told Reuters Health.

"Our goal in doing this analysis is to help patients and
health care providers understand the relative risks and
benefits of colorectal cancer screening," Ko said. "Our
analysis does show that colorectal cancer screening is unlikely
to benefit some patient subgroups -- especially those who are
older or who have significant comorbidities."

Dr. Ko and Dr. Amnon Sonnenberg from Oregon Health and
Science University, Portland, examined the probability of
colorectal cancer screening-related benefits and harms in older
patients with varying health status.

Colorectal cancer incidence rates increase with age, the
authors note, but the cumulative lifetime odds of dying from
colorectal cancer decrease in men and women with advancing age
who often have co-morbid illnesses.

Under the assumption that colorectal cancer screening is
unlikely to benefit those whose life expectancy is less than
five years, the researchers identified four groups that would
not benefit from colorectal screening: men 75 to 84 years old
with poor health; men 85 years and older with average or poor
health; women 80 to 89 years old with poor health; and women 90
years and older with average or poor health.

Even for those likeliest to benefit from colorectal cancer
screening, the number who would have to be screened to prevent
one colorectal cancer death ranged from 42 (with colonoscopy
screening) to 177 (with fecal occult blood test screening)
among men aged 70 to 74 years in good health.

The results were similar for women aged 70 to 74 years in
good health.

The risk of complications varied with the colorectal cancer
screening method, the researchers note. For colonoscopy
screening, for example, complications outweigh the potential
benefits for women aged 75 to 79 years in poor health, women
aged 85 to 89 years in average health, men aged 70 to 74 years
in poor health, and men aged 90 to 94 years in good health.

"The decision to pursue screening," Ko concludes, "should
be individualized and should take into account a patient's life
expectancy, comorbidity, and preferences."

In a commentary, Dr. Carmen Lewis from University of North
Carolina, Chapel Hill, says "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."

SOURCE: Gastroenterology, October 2005.