The medical impact of emergent banning of N-nitrosodimethylamine: contaminated antihypertensive drug

Background/Aims: Concerns exist regarding the potential carcinogenic effect of N-nitrosodimethylamine (NDMA) as a contaminant of the antihypertensive medication, valsartan. This study evaluated the association of NDMA-contaminated valsartan with cancer incidence.Methods: Nationwide longitudinal observational cohort of 3,231,212 participants from the National Health Insurance Service of South Korea consisted and was followed up more than 7 years. We performed 1:1:1 pairwise propensity score matching (PSM) of NDMA-uncontaminated, NDMA-contaminated, and initially-suspended-but-finally confirmed as NDMA-uncontaminated valsartan user-groups. The primary outcome was any primary cancer incidence. The secondary outcome was the incidences of 12 organ-specific cancers. The risks of all-cause and cardiovascular deaths were estimated before and after the withdrawal of valsartan.Results: Among participants (59.5 ± 13.1 yr; male, 53.5%), valsartan new users had adjusted hazard ratios and 95% confidence intervals of 1.069 (1.054–1.085) and 1.172 (1.128–1.216) for any cancer in the NDMA-exposed period (versus NDMA-unexposed) before and after PSM, respectively. Regardless of PSM, prostate cancer risk increased significantly. All-cause and cardiovascular mortality did not differ significantly with NDMA exposure before and after emergent banning.Conclusions: Use of valsartan products contaminated with NDMA was associated with a modestly increased risk of overall cancer compared with uncontaminated products, a finding that requires confirmation in further studies.