This guideline is controversial. Americans generally reject the idea that life expectancy should be a factor in medical care decisions. And many experts, notably the gastroenterologists who perform colonoscopies, say an age cutoff is too simplistic.
"The chance of getting colorectal cancer continues to increase with age. If I have a patient over 75 who is healthy, I would" screen, said Scott Goldstein, director of colon and rectal surgery at Thomas Jefferson University. "The American Cancer Society doesn't endorse an age limit."
For the study, published this week in JAMA Internal Medicine, University of Texas researchers analyzed nine years of Medicare claims data for all patients 70 and older in Texas, and a sample in the United States. They found 23.5 percent of colonoscopies may have been unnecessary based on the frequency or the patient's age.
Previous studies have found even higher screening rates among veterans over 70 with severe chronic illnesses and life expectancies under five years.
The new study acknowledged that doctors may disagree with the guidelines. Other reasons for overuse of colonoscopies include poor communication between doctors and "financial incentives."
"Inappropriate use of colonoscopy involves unnecessary risk for older patients and consumes resources that could be used more effectively," wrote the Texas authors, led by population researcher Kristin M. Sheffield.
In recent years, the Preventive Services Task Force stirred controversy by recommending less use of PSA tests for prostate and mammograms for breast cancer, saying risks of overdiagnosis and treatment outweigh the benefit of a few lives saved.
But colonoscopy - the colon is examined using a flexible, lighted tube inserted through the rectum - is different.
The checkup can truly prevent, not just detect, cancer. Colon cancer begins with precancerous growths called polyps; removal of polyps during a colonoscopy keeps them from becoming malignant.
Although the procedure requires loathed bowel-cleanout drugs and sedation, complications are rare. A separate study in the journal found that about 0.2 percent of patients suffered problems such as colon perforation.
Colonoscopy "is the singular glowing example of a screening test that decreases the incidence of cancer," said Anil K. Rustgi, chief of gastroenterology at the University of Pennsylvania. "It is invasive, but for the information gained, the investment is worth it."
Colon cancer is the second-leading cause of cancer death in this country, ending more than 50,000 lives a year. Experts estimate 18,800 could be saved if the rate of screening rose from 60 percent of all eligible adults to 80 percent.
James Izanec, a gastroenterologist with Allied Gastrointestinal Associates in South Jersey, said of the new study: "It's unfortunate that the take-home message is that there is too much screening, when the real issue is too few people are getting screened."
The Race/Walk For Colon Cancer
What: Get Your Rear in Gear 5K/10K runs, 2-mile walk, and kids' fun run to raise money for colon cancer awareness.
When: On-site registration begins 7:30 a.m. Sunday; event start times
from 8:45-9:15 a.m.
Where: Memorial Hall/Please Touch Museum, 4231 Avenue of the Republic, Fairmount Park.
Cost: $32 for adults, $15 for children.
Information: Details on events and on early packet pickup: 856-371-9238, www. getyourrearingear.com
Contact Marie McCullough at 215-854-2720 or firstname.lastname@example.org.