Abstract 3944: Addressing stomach cancer disparities by assessing Helicobacter pylori infections among American Indian adults from the Navajo Nation
Authors: Pete Dornell , Salama Nina R. , Lampe Johanna W. , Wu Michael C. , Phipps Amanda I. 
Published: March 2024

Abstract
Background. The Navajo Nation, the largest tribe in the United States (US), is experiencing a high burden of stomach cancer, possibly due to a high prevalence of Helicobacter pylori (Hp) infection. Hp is a major risk factor for stomach cancer and Hp strains that carry the cagA-gene are linked to greater gastrointestinal disease severity. Yet little research has investigated the prevalence and correlates of Hp and cagA infection in Navajo people. We assessed the prevalence and correlates of Hp infection and cagA-gene carriage in adult tribal members residing in the Navajo Nation.
Methods and Material. We conducted a community-based cross-sectional study in the Navajo Nation in 2021 during the COVID-19 pandemic. Participants were recruited using online and offline platforms, including social media, a study website, newspaper advertisements, flyers, word of mouth, and community outreach. Stool samples collected from participants were analyzed with droplet digital PCR for Hp 16S and cagA virulence genes. Demographic characteristics, health, and dietary factors were collected from self-administered health and food questionnaires sent via mail.
Results. Of 99 participants, half (49.5%) were 18-44 years old and 73.7% were female. About sixty percent (57.7%, 95% CI: 47.6-67.3) of participants were infected with Hp, twice the US population prevalence (27%). Among Hp-infected participants, 76.7% (95% CI: 64.0-86.6) were cagA-gene positive, four times the cagA gene prevalence in White people (19%). Controlling for age and sex, monthly use of Navajo herbal medicines was positively associated with Hp infection (OR=3.73, 95% CI: 1.05-17.87). No significant associations with Hp and cagA-gene were observed with other risk factors such as older age, males, lower education, and high sodium intake.
Conclusion. A substantial proportion of Navajo adults in our study had Hp and cagA-positive infections. Given studies showing the antibacterial activity of Indigenous herbal medicines, monthly use of Navajo herbal medicines was an unexpected risk factor for Hp infection. This observation may be due to reverse causality, where participants with gastrointestinal conditions used Navajo herbal medicines for gastrointestinal symptom relief, particularly when participants had limited access to healthcare services due to the COVID-19 pandemic. Possible environmental transmission of Hp in the preparation of herbal medicines (i.e., water source, utensils) could be another source of exposure. Given the high burden of Hp and cagA-positive infections, culturally tailored health education strategies and interventions addressing these infections present an opportunity for research and cancer prevention among Navajo adults.
Citation Format: Dornell Pete, Nina R. Salama, Johanna W. Lampe, Michael C. Wu, Amanda I. Phipps. Addressing stomach cancer disparities by assessing Helicobacter pylori infections among American Indian adults from the Navajo Nation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3944.