December 18, 2018
3 min read

Negative colonoscopy linked to lower colorectal cancer risk after 12 years

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Average risk patients with a negative colonoscopy demonstrated a lower risk for overall, proximal, distal, early-stage and advanced-stage colorectal cancer and related deaths for more than 12 years after screening, according to findings published in JAMA Internal Medicine.

“Guidelines recommend a 10-year rescreening interval after a colonoscopy with normal findings (negative colonoscopy results), but evidence supporting this recommendation is limited,” Jeffrey K. Lee, MD, MAS, from the department of gastroenterology at Kaiser Permanente San Francisco, and colleagues wrote.

Lee and colleagues conducted a retrospective cohort study to compare the long-term risks of colorectal cancer and colorectal cancer deaths in patients with a negative colonoscopy vs. unscreened patients. The researchers enrolled 1,251,318 average-risk screening-eligible patients between the ages of 50 and 75 years between Jan. 1, 1998, and Dec. 31, 2015 (49% men; mean age, 55.6 years).

Colorectal screening was assessed as a time-varying exposure. All participants contributed person-time unscreened until they were either screened by fecal test, sigmoidoscopy or colonoscopy or censored, defined as dying, being diagnosed with colorectal cancer, having a health plan membership terminated or reaching the end of the study. Participants with a negative colonoscopy contributed person-time in the negative colonoscopy results group until they were censored.

The analysis was adjusted for age, sex, race/ethnicity, Charlson comorbidity score and BMI. Over more than 12 years of follow-up, the risk for colorectal cancer and related deaths was lower among participants with a negative colonoscopy result compared with those who were unscreened.

A total of 5,743 colorectal cancers were diagnosed; of which, 31.7% were proximal cancers and 45.1% were advanced-stage cancers.

At the current guideline-recommended 10-year rescreening interval, the risk for colorectal cancer was 46% lower (HR = 0.54; 95% CI, 0.31-0.94) and the risk for related deaths was 88% lower (HR = 0.12; 95% CI, 0.02-0.82).

The risk of proximal colorectal cancer was 20% to 87% lower and the risk of distal cancer was 50% to 99% lower in the negative colonoscopy results group during follow-up versus the unscreened group.

“Our findings can inform guideline recommendations for rescreening and future studies to evaluate the costs and benefits of earlier vs. later rescreening intervals,” Lee and colleagues concluded. – by Alaina Tedesco


Disclosures: The authors report no relevant financial disclosures.