Penicillins might increase colorectal cancer risk

Several studies have reported that the composition of the bacteria in the gastrointestinal tract influences the risk of developing colorectal cancer (CRC). Now, a new study suggests that multiple courses of penicillins may modestly increase CRC risk.

Researchers used a UK primary care database to match 20,990 people with the malignancy to 82,054 controls. Neither antivirals nor anti-fungals influenced CRC risk. However, during a median follow up of 6.5 years, antibiotics seemed to increase CRC risk. For example, initial antibiotic use more than one year before the index date increased CRC risk among patients taking nitroimidazoles (9%), penicillins (6%), cephalosporins (5%) and trimethoprim plus sulfamethoxazole (5%), but not macrolides or tetracyclines.