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Obesity surgery associated with long-term risk for colorectal cancer

Obesity surgery was associated with long-term increased risk for colorectal cancer, according to results of a retrospective cohort study.

Human tissue biomarker studies and epidemiological observations suggested an association between obesity surgery and cancer, but the long-term risks were unclear, according to background information in the study.

Researchers in Sweden evaluated data from 77,111 individuals defined as obese who were enrolled in a nationwide register between 1980 and 2009. Among the study population, 15,095 participants had obesity surgery and 62,016 did not.

The investigators compared the risk for colorectal cancer between the two groups, who were matched for age and sex.

Over a median of 10 years, 70 individuals in the surgery cohort were diagnosed with colorectal cancer, equating to a standardized incidence ratio (SIR) of 1.60 (95% CI, 1.25-2.02). Among those who underwent obesity surgery 10 or more years prior to the time of the analysis, the SIR increased to 2.00 (95% CI, 1.48-2.64).

Over a median of 7 years, researchers reported 373 participants in the nonsurgery group developed colorectal cancer, equating to an SIR of 1.26 (95% CI, 1.14-1.40).

“Obesity surgery seems to be associated with an increased risk of colorectal cancer over time,” the researchers wrote. “These findings would prompt evaluation of colonoscopy surveillance for the increasingly large population who undergo obesity surgery.”

Disclosure: The researchers report no relevant financial disclosures.

Harry S. Jacob, MD

Harry S. Jacob, MD, FRCPath(Hon)

  • It would be interesting to know if dichotomous results could be teased out by comparing bypass surgery to gastric banding outcomes. Differing microbial residence in the altered postoperative intestines might provide insight into these provocative findings.

    • Harry S. Jacob, MD, FRCPath(Hon)
    • HemOnc Today Chief Medical Editor
  • Disclosures: Jacob reports no relevant financial disclosures.