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Negative Colonoscopy and Long-Term Risk of Colorectal Cancer

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Key Points

  • Rescreened patients had a 46% lower risk of colorectal cancer.
  • Rescreened patients had an 88% lower risk of related deaths.

Ten years after a negative colonoscopy, patients who were rescreened for colorectal cancer had a lower risk of being diagnosed with and were less likely to die from colorectal cancer compared with those who did not undergo colorectal cancer screening, according to a study published by Lee et al in JAMA Internal Medicine.

“Our study shows that following a colonoscopy with normal findings, there is a reduced risk of developing and dying from colorectal cancer for at least 10 years,” said study leader Jeffrey Lee, MD, gastroenterologist and research scientist at the Division of Research at Kaiser Permanente. “These findings suggest that physicians can feel confident following the guideline-recommended 10-year rescreening interval after a negative colonoscopy in which no colorectal cancer or polyps were found. There is now solid evidence supporting that recommendation.”

The U.S. Preventive Services Task Force currently recommends colorectal cancer screening for adults at average risk between 50 and 75 years old, with either colonoscopy every 10 years, sigmoidoscopy every 5 years, or fecal testing every year, assuming these tests produce normal findings. Before this study, there was little evidence supporting the 10-year recommended screening interval after a colonoscopy with normal findings, Dr. Lee pointed out. “That uncertainty was concerning, because colorectal cancer is the second leading cause of cancer-related deaths in the United States.”

Study Methods and Results

To help address the evidence gap for when to rescreen, the retrospective study examined the long-term risk of colorectal cancer and related deaths after a negative colonoscopy in comparison to no screening. A total of 1,251,318 average-risk screening-eligible patients (aged 50–75 years) between January 1, 1998, and December 31, 2015, were included in the study.

Compared with the unscreened participants, those with a negative colonoscopy result had a reduced risk of colorectal cancer and related deaths. Although reductions in risk were attenuated with increasing years of follow-up, there was a 46% lower risk of colorectal cancer (hazard ratio [HR] = 0.54; 95% confidence interval [CI] = 0.31–0.94) and 88% lower risk of related deaths (HR = 0.12; 95% CI = 0.02–0.82) at the 10-year rescreening interval.

The study authors concluded, “Our study findings may be able to inform guidelines for rescreening after a negative colonoscopy result and future studies to evaluate the costs and benefits of earlier vs later rescreening intervals.”

“This large study is the first with a high enough number of average-risk individuals to evaluate cancer risks after colonoscopy examinations, compared with no screening,” said senior author Douglas Corley, MD, PhD, gastroenterologist and research scientist with the Division of Research at Kaiser Permanente. “Such information provides greater certainty regarding the appropriate timing for rescreening after a negative colonoscopy.”

Disclosure: The National Cancer Institute funded the study through its Population-Based Research Optimizing Screening Through Personalized Regimens consortium. The study authors’ full disclosures can be found at jamanetwork.com.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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