BMC Seminar Thursday 18th of January at 11:35 in room 343 Læknagarður

Speaker: Óskar Örn Hálfdánarson, a PhD student of Eiríkur Steingrímsson, Helga Zoega, Helga M. Ögmundsdóttir, Margrét Helga Ögmundsdóttir and Katja Fall at the Faculty of Medicine, School of Health Sciences, University of Iceland.

Title: Proton pump inhibitor use and risk of breast cancer, prostate cancer and melanoma: A Population-based Case-Control Study

Abstract: Proton pumps of the v-ATPase type have been shown to be overexpressed in the plasma membrane of certain cancer cells, where they are believed to contribute to the acidification of the tumor microenvironment. Acidic tumor microenvironments have been associated with increased drug resistance and aggressive behavior through enhanced metastatic potential. Proton pump inhibitors (PPIs) are pro-drugs that become active in acidic environments and are able to bind to the v-ATPase and inhibit acid secretion. PPIs are one of the most widely prescribed drugs and their use has been steadily increasing for several years.

The objective of this population based nested case-control study was to determine the association between exposure to proton pump inhibitors and the risk of a first-time diagnosis of 1) breast cancer, 2) prostate cancer and 3) melanoma.

From the Icelandic Cancer Registry, we identified 1889 patients diagnosed with breast cancer, 2089 patients diagnosed with prostate cancer, and 428 patients diagnosed with melanoma between 2004-2014. We matched 10 controls to each case on birth year, sex and calendar time using risk-set-sampling. We obtained information on PPI exposure from the Icelandic Medicine Registry. A conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between PPI use and a first-time diagnosis of the cancers of interest. Furthermore, we stratified all analyses by cumulative exposure to PPIs ( 30 days, 31-90 days, 91-360 days, 361-720 days, 721-1080 days, >1080 days).

In our preliminary results, we did not observe an association between PPI use and the of being diagnosed with any of the cancer types of interest in our study. Furthermore, we did not find a clear dose response related to cumulative exposure (in days) between PPI use and any of the cancers of interest.