Early Morning Colon Cancer Tests Work Best

More Polyps Found in Colon Cancer Screenings Performed Before 8:30 a.m., Study Shows

Reviewed by Louise Chang, MD on November 06, 2009
From the WebMD Archives

Nov. 6, 2009 -- Colon cancer screening exams may be more effective if done very early in the day rather than later, yielding more polyps per patient, says a new study.

Not only are more polyps per patient found the earlier the procedures are done, but fewer polyps seem to be found hour by hour as the day progresses, says Brennan M.R. Spiegel, MD, MSHS, director of the UCLA/Veterans Affairs Center for Outcomes Research and Education reporting in the November issue of the journal Clinical Gastroenterology and Hepatology.

“Our research was conducted at an academic-affiliated facility that far exceeds published quality benchmarks for colonoscopy outcomes,” Spiegel says in a news release. “So, if this is occurring at such a high-performing academic center, it is probably happening at other facilities across the country.”

The findings could be significant because colonoscopies allow for the identification and removal of polyps from the entire colon and rectum. Polyp removal has been associated with a 60% to 90% reduction in colorectal cancer, the second leading cause of cancer-related deaths in the United States.


The researchers looked at colonoscopy records of 477 patients scheduled for colonoscopies at a VA medical center unit affiliated with the University of California at Los Angeles (UCLA) between September 2006 and September 2007.

Early cases were done at 8:30 a.m. or earlier.

They found that there were 20% more polyps found per patient in the early cases compared to cases done after 8:30 a.m. There were no differences in factors such as duration of the procedures, family or personal history of colorectal cancer, and age between the early and later cases. The researchers also took into account the level of physician experience.

“Successful colonoscopy procedures depend on a number of key patient, provider, and procedural factors, and time of day may be important as well,” says Spiegel, an assistant professor of digestive diseases at UCLA’s David Geffen School of Medicine.

Although he and fellow researchers say this finding is important, they stress that more research needs to be done to establish with more certainty why the number of polyps found later in the day decreases and to pinpoint ways to improve outcomes.


The researchers suggest possible reasons why more polyps are found early in the day:

  • Better bowel preparation the night before by patients
  • Fatigue of physicians and assistants, who, like truck drivers, pilots, and others who perform repetitive procedures, may become less alert as the hours pass. “Cognitive and perceptual errors accrue in the face of prolonged and repetitive activities,” the authors write. Ongoing demands may lead to rushing, including disruptions such as incoming phone calls, nursing shift changes, and conversations.

“Given the prolonged, oftentimes repetitious, sometimes distractible nature of outpatient colonoscopy, it is possible that cognitive errors happen in the endoscopy suite, just as they occur in other prolonged and repetitious activities,” the authors write.

Spiegel says that it would be a mistake for patients to insist on being the first case of the day because colonoscopies are known to be a highly effective way to screen for colon cancer.

“Patients should feel confident that colonoscopy is helpful regardless of time of day and should be more focused on the quality and experience of their doctor rather than the time of the appointment,” Spiegel says in a news release.

WebMD Health News



News release, UCLA.

Chan, M. Clinical Gastroenterology and Hepatology, November 2009.

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