Helicobacter pylori was not detected in oral squamous cell carcinomas from cohorts of Norwegian and Nepalese patients.

Helicobacter pylori (HP) infection is an established causative agent for gastric cancer. Although the oral cavity is a part of the gastrointestinal system, the presence and possible causative role of HP in oral squamous cell carcinoma (OSCC) is a subject of controversy. Therefore, the current study aimed to investigate HP infection in two cohorts of OSCC patients with different demographic characteristics, lifestyles and habitual risk factors. A total of 242 formalin-fixed paraffin-embedded OSCC specimens from two different patient cohorts (Norway, n = 171 and Nepal, n = 71) were used to examine HP using immunohistochemistry (IHC) and quantitative polymerase chain reaction (qPCR). Two different HP specific genes (23S rRNA and ureA) were used for TaqMan-based qPCR, and for subsequent verification using HP specific RIDAGENE HP kit and SYBR Green based qPCR. All of the OSCC specimens from both cohorts were found to be negative for HP infection with IHC and qPCR, although the positive control specimens tested positive. Our findings suggest that HP is absent in the examined OSCC cohorts, irrespective of race, lifestyle and habitual risk factors. This indicates that, in contrast to gastric cancer, HP is an unlikely contributing factor for OSCC pathogenesis.