Delaying Colonoscopy for 9 Months or More After Positive Fecal Screening Test May Increase Risk of Colorectal Cancer

Key Points

  • Compared with colonoscopy follow-up times of 8 to 30 days, the study found no significant differences in risk for any colorectal cancer or an advanced cancer with colonoscopy follow-up times of 2, 3, 4, 6, 7, or 9 months.
  • By 10 to 12 months, however, the risk of any colorectal cancer increased by approximately 50%, and the risk of an advanced cancer almost doubled.
  • Waiting longer than 12 months increased the risks even more, to more than double the risk for any cancer and triple the risk for an advanced cancer.

The risk of colorectal cancer increased significantly when colonoscopy was delayed by more than 9 months following a positive fecal screening test, according to a large Kaiser Permanente study published by Rutter et al in the Journal of the American Medical Association.

“With this study, we have strong evidence that a colonoscopy should be performed within several months of a positive fecal screening test,” said lead author Douglas A. Corley, MD, PhD, a Kaiser Permanente gastroenterologist and research scientist in Northern California.

The fecal immunochemical test screens for colorectal cancer by detecting small amounts of blood in the stool. When blood is detected, gastroenterologists perform a colonoscopy to detect and possibly remove cancerous or precancerous polyps before there are any symptoms.

Study Findings

The JAMA study reviewed time-to-colonoscopy for 70,124 Kaiser Permanente members in California between 50 and 75 years old with an average risk for colorectal cancer, who had positive fecal immunochemical test results from 2010 through 2013. About 40% received follow-up colonoscopies within 1 month, 64% within 2 months, and 74% within 3 months.

Compared with colonoscopy follow-up times of 8 to 30 days, the study found no significant differences in risk for any colorectal cancer or an advanced cancer with colonoscopy follow-up times of 2, 3, 4, 6, 7, or 9 months. By 10 to 12 months, however, the risk of any colorectal cancer increased by approximately 50%, and the risk of an advanced cancer almost doubled. Waiting longer than 12 months increased the risks even more, to more than double the risk for any cancer and triple the risk for an advanced cancer.

In the study, 3% of the people with positive fecal test results were diagnosed with colorectal cancer (2,191 total cases). Less than 1% of these (601 cases) were advanced cancers. The study results were adjusted for differences between patients who had earlier vs later exams. The findings should help to alleviate anxiety for people who have a positive test result, said Kaiser Permanente gastroenterologist Theodore R. Levin, MD, the study’s senior author and Clinical Lead for Colorectal Cancer Screening in Kaiser Permanente’s Northern California Region.

“It is a lot of effort for patients to arrange a colonoscopy, given the need for time off work and scheduling someone to accompany them home,” Dr. Levin said. “Our study shows that you should get your colonoscopy done, and you should do it as soon as is feasible, but any time within a few months … is reasonably safe based on these data.”

Colorectal cancer is the second-leading cause of cancer death in the United States, according to the U.S. Centers for Disease Control and Prevention. The U.S. Preventive Services Task Force recommends that people at average risk be screened with a fecal test every year between the ages 50 and 75, a colonoscopy every 10 years, or flexible sigmoidoscopy every 5 years.

“Until this study, very little evidence was available regarding when colorectal cancer begins to progress,” said coauthor Joanne Schottinger, MD, Chair of the Regional Cancer Committee for the Southern California Permanente Medical Group. “Our research confirms that it is very important for patients to have a colonoscopy within a few months of receiving a positive [fecal immunochemical test] screening.”

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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