Colon cancer screening more effective earlier in day, UCLA study finds

While risk to individuals is low, findings indicate need for broader system changes

The effectiveness of a screening colonoscopy may depend on the time of day it is performed. According to a new UCLA study, early-morning colonoscopies yielded more polyps per patient than later screenings, and fewer polyps were found hour by hour as the day progressed.

The findings, published in the November issue of the journal Clinical Gastroenterology and Hepatology, point to the need for more research in this area to possibly improve outcomes for colonoscopy procedures. While the current study was done at a single institution, the clinical setup is much the same in other practice settings, the researchers said.

"Our research was conducted at an academic-affiliated facility that far exceeds published quality benchmarks for colonoscopy outcomes," said study author Dr. Brennan M.R. Spiegel, director of the UCLA/Veterans Affairs Center for Outcomes Research and Education. "So, if this is occurring at such a high-performing academic center, it is probably happening at other facilities across the country."

Spiegel noted that although this is a new area of research, other studies have reached similar conclusions, including recent research from the Cleveland Clinic published in the July issue of the American Journal of Gastroenterology.

A colonoscopy is the only test that allows the identification and removal of polyps from the entire colon. Studies have shown that polyp removal has been associated with a 60- to 90-percent reduction in colorectal cancer, which is the second leading cause of death in the United States.

"Successful colonoscopy procedures depend on a number of key patient, provider and procedural factors — and time of day may also be important as well," said Spiegel, who is an assistant professor of digestive diseases at the David Geffen School of Medicine at UCLA and the VA Greater Los Angeles Healthcare System.