Proton pump inhibitors and the risk of pancreatic cancer

Abstract

Dear editor, We would like to thank Dr. Shih-Wei Lai for the feedback on our study [1, 2]. As mentioned by Dr. Lai, longterm PPI treatment is rarely indicated, yet tens of thousands of people are on maintenance treatment of PPIs globally. A quick non-comprehensive overview of recent populationestimates, shows approximately 7% of Danish adults [3], 11% of Swedish residents [4], 14% of Hungarian adults [5], 30% of French adults [6], and 33% of Iceland residents[7] used PPIs on an annual basis (ranging from 1 prescription to daily use). Studies on the carcinogenic effect of PPIs should indeed consider confounding by indication since PPIs are often administered to prevent upper-gastro-intestinal cancer in high-risk patients. Yet, it is important to assess if this increased risk is present among those with an expected increased risk and those without. As we know from the literature, many people without clear risk factors for uppergastrointestinal cancer do use PPI use daily, although it is not according to prescription guidelines [8]. Stratified assessment by indication may therefore help to distinguish if identified risks are independent of the indication. Even if PPIs would not be an independent risk factor for (gastro-intestinal) cancer [9], potential side-effects should be considered, ranging from acute gastrointestinal infections to reduced life expectancy [8, 10]. A main concern is that PPIs are often prescribed without a thorough gastrointestinal investigation and follow-up, which may contribute to later diagnosis of gastro-intestinal cancer, and consequent worse prognosis. Therefore, regular follow-up and re-evaluation of treatment are warranted for all chronic PPI users.