Assessing Helicobacter pylori and Diet to Develop Cancer Interventions in American Indian Communities in the Southwest

Fred Hutchinson Cancer Center, Seattle WA

Investigators

Abstract

A substantial burden of gastric cancer, a highly fatal cancer, continues to be observed in American Indians (AI) and Alaska Natives (AN). Among the largest tribe in the US, people from the Navajo Nation suffer from a high rate of gastric cancer compared to the general Arizona and New Mexico population (15.0 per 100,000 persons vs. 4.3 per 100,000 persons). A possible contributing factor underlying this disparity in the Navajo Nation is the high prevalence of infection with Helicobacter pylori (Hp), a bacterium that colonizes the stomach and is the primary risk factor for gastric cancer. Studies show a high burden of Hp infection in the Navajo people, with the prevalence two times higher in the Navajo population compared to the US general population. Research finds that successful treatment to eradicate Hp infection is essential for improving patient outcomes and reducing the burden of Hp; however, treatment can be unsuccessful due to low medication adherence, clinic-level barriers, re-exposure to Hp, and antibiotic resistance. Therefore, a high burden of Hp infection can remain through persistent Hp infection or reinfection. Research on persistent Hp infection and re-infection and barriers to treatment success is unknown among the Navajo people. My research allows me to leverage my previous experience working with the Navajo Nation to determine the incidence and timing of both persistent Hp infection and re-infection (Aims 1a & 1b) and identify strategies to reduce them (Aim 2), using quantitative and qualitative research approaches. I will implement my research among adults residing in the Navajo Nation. My aims in the postdoctoral K00 phase are two-fold. For Aims 1a-b, I will use my gained expertise in Hp from my F99 pre-doctoral phase to characterize the incidence for both persistent Hp infection and Hp re-infection, including correlates for persistent Hp infection and re-infection, in Hp-infected patients in the Navajo Nation using a retrospective cohort study. I will conduct time-to-event analyses to evaluate the incidence of persistent Hp infection and Hp re-infection and its correlates in Hp-infected patients over a 10-year observation period using longitudinal clinical data from the Navajo Area Indian Health Service. I will compare the incidence found in this study with other US populations and assess covariates (i.e., demographics, health conditions, behavioral factors) associated with persistent Hp infection and reinfection. For Aim 2, I will conduct a qualitative study using my gained training in qualitative research methods (F99) to identify facilitators and barriers to using Hp treatment in the Navajo Nation. I will recruit 35 Navajo adults whom self-report prior use of Hp treatment to participate in in-depth interviews. Standard qualitative data analysis techniques will be used to identify main themes surrounding patient experience with Hp treatment. This proposed research can fill important gaps needed to understand risk factors for gastric cancer among the Navajo, a population experiencing a high Hp infection disease burden, to develop health-promoting interventions to improve cancer outcomes, in alignment with the mission of the NCI and NIH.