Long-Term Use of Antibiotics Associated with Later-Life Colorectal Adenomas

By Joe Elia

Edited by David G. Fairchild, MD, MPH, and Lorenzo Di Francesco, MD, FACP, FHM

Antibiotic use in young adulthood and middle age is associated in a dose-dependent relation to the presence of colorectal adenomas after age 60, an observational study in Gut finds.

Researchers examined the records of some 17,000 Nurses' Health Study participants aged 60 and older who'd reported their antibiotic use between ages 20 and 39, and again between ages 40 and 59, as well as use within the past 4 years. All had undergone colonoscopy after age 59.

Longer-duration antibiotic use during earlier life was associated with greater risk for adenomas, relative to non-using participants. For example, antibiotic use for 2 months or more between ages 40 and 59 showed a relative risk of about 1.7, while use for 1 to 14 days showed a risk of about 1.3. However, recent use showed no association.

The authors write that the effect is biologically plausible, given the effects of antibiotics on the gut's microbiome.