Gastric Cancer Among American Indian and Alaska Native Populations in the United States, 2005-2016

Stomach Cancer Prediction Model (SCoPM): An approach to risk stratification in a diverse U.S. population

BACKGROUND AND AIMS

Population-based screening for gastric cancer (GC) in low prevalence nations is not recommended. The objective of this study was to develop a risk-prediction model to identify high-risk patients who could potentially benefit from targeted screening in a racial/ethnically diverse regional US population.

METHODS

We performed a retrospective cohort study from Kaiser Permanente Southern California from January 2008-June 2018 among individuals age ≥50 years. Patients with prior GC or follow-up <30 days were excluded. Censoring occurred at GC, death, age 85 years, disenrollment, end of 5-year follow-up, or study conclusion. Cross-validated LASSO regression models were developed to identify the strongest of 20 candidate predictors (clinical, demographic, and laboratory parameters). Records from 12 of the medical service areas were used for training/initial validation while records from a separate medical service area were used for testing.

RESULTS

1,844,643 individuals formed the study cohort (1,555,392 training and validation, 289,251 testing). Mean age was 61.9 years with 53.3% female. GC incidence was 2.1 (95% CI 2.0-2.2) cases per 10,000 person-years (pyr). Higher incidence was seen with family history: 4.8/10,000 pyr, history of gastric ulcer: 5.3/10,000 pyr, H. pylori: 3.6/10,000 pyr and anemia: 5.3/10,000 pyr. The final model included age, gender, race/ethnicity, smoking, proton-pump inhibitor, family history of gastric cancer, history of gastric ulcer, H. pylori infection, and baseline hemoglobin. The means and standard deviations (SD) of c-index in validation and testing datasets were 0.75 (SD 0.03) and 0.76 (SD 0.02), respectively.

CONCLUSIONS

This prediction model may serve as an aid for pre-endoscopic assessment of GC risk for identification of a high-risk population that could benefit from targeted screening.

Population-based evaluation of disparities in stomach cancer by nativity among Asian and Hispanic populations in California, 2011-2015

BACKGROUND

Stomach cancer incidence presents significant racial/ethnic disparities among racial/ethnic minority groups in the United States, particularly among Asian and Hispanic immigrant populations. However, population-based evaluation of disparities by nativity has been scarce because of the lack of nativity-specific population denominators, especially for disaggregated Asian subgroups. Population-based stomach cancer incidence and tumor characteristics by detailed race/ethnicity and nativity were examined.

METHODS

Annual age-adjusted incidence rates were calculated by race/ethnicity, sex, and nativity and tumor characteristics, such as stage and anatomic subsite, were evaluated using the 2011-2015 California Cancer Registry data. For Hispanic and Asian populations, nativity-specific population counts were estimated using the US Census and the American Community Survey Public Use Microdata Sample data.

RESULTS

During 2011-2015 in California, 14,198 patients were diagnosed with stomach cancer. Annual age-adjusted incidence rates were higher among foreign-born individuals than their US-born counterparts. The difference was modest among Hispanics (∼1.3-fold) but larger (∼2- to 3-fold) among Chinese, Japanese, and Korean Americans. The highest incidence was observed for foreign-born Korean and Japanese Americans (33 and 33 per 100,000 for men; 15 and 12 per 100,000 for women, respectively). The proportion of localized stage disease was highest among foreign-born Korean Americans (44%); a similar proportion was observed among US-born Korean Americans, although numbers were limited. For other Asians and Hispanics, the localized stage proportion was generally lower among foreign-born than US-born individuals and lowest among foreign-born Japanese Americans (23%).

CONCLUSIONS

Nativity-specific investigation with disaggregated racial/ethnic groups identified substantial stomach cancer disparities among foreign-born immigrant populations.

Incidence of Stomach, Liver, and Colorectal Cancers by Geography and Social Vulnerability Among American Indian and Alaska Native Populations, 2010-2019

Social determinants of health and associated systems, policies, and practices are important drivers of health disparities. American Indian and Alaska Native (AI/AN) populations in the United States have elevated incidence rates of stomach, liver, and colorectal cancers compared with other racial/ethnic groups. In this study, we examined incidence rates of 3 types of gastrointestinal cancer among non-Hispanic AI/AN (NH-AI/AN) and non-Hispanic White (NHW) populations by geographic region and Social Vulnerability Index (SVI) score. Incident cases diagnosed during 2010-2019 were identified from population-based cancer registries linked with the Indian Health Service patient registration databases. Age-adjusted incidence rates (per 100,000 population) for stomach, liver, and colorectal cancers were compared within NH-AI/AN populations and between the NH-AI/AN and NHW populations by SVI score. Rates were higher among NH-AI/AN populations in moderate- and high-SVI-score counties in Alaska, the Southern Plains, and the East than in low-SVI counties. Incidence rates among NH-AI/AN populations were elevated when compared with NHW populations by SVI category. Results indicated that higher social vulnerability may drive elevated cancer incidence among NH-AI/AN populations. Additionally, disparities between NH-AI/AN and NHW populations persist even when accounting for SVI. Exploring social vulnerability can aid in designing more effective interventions to address root causes of cancer disparities among AI/AN populations.

Misracialization of Indigenous people in population health and mortality studies: a scoping review to establish promising practices

Indigenous people are often misracialized as other racial or ethnic identities in population health research. This misclassification leads to underestimation of Indigenous-specific mortality and health metrics, and subsequently, inadequate resource allocation. In recognition of this problem, investigators around the world have devised analytic methods to address racial misclassification of Indigenous people. We carried out a scoping review based on searches in PubMed, Web of Science, and the Native Health Database for empirical studies published after 2000 that include Indigenous-specific estimates of health or mortality and that take analytic steps to rectify racial misclassification of Indigenous people. We then considered the weaknesses and strengths of implemented analytic approaches, with a focus on methods used in the US context. To do this, we extracted information from 97 articles and compared the analytic approaches used. The most common approach to address Indigenous misclassification is to use data linkage; other methods include geographic restriction to areas where misclassification is less common, exclusion of some subgroups, imputation, aggregation, and electronic health record abstraction. We identified 4 primary limitations of these approaches: (1) combining data sources that use inconsistent processes and/or sources of race and ethnicity information; (2) conflating race, ethnicity, and nationality; (3) applying insufficient algorithms to bridge, impute, or link race and ethnicity information; and (4) assuming the hyperlocality of Indigenous people. Although there is no perfect solution to the issue of Indigenous misclassification in population-based studies, a review of this literature provided information on promising practices to consider.

Infectious diseases in Indigenous populations in North America: learning from the past to create a more equitable future

The COVID-19 pandemic, although a profound reminder of endured injustices by and the disparate impact of infectious diseases on Indigenous populations, has also served as an example of Indigenous strength and the ability to thrive anew. Many infectious diseases share common risk factors that are directly tied to the ongoing effects of colonisation. We provide historical context and case studies that illustrate both challenges and successes related to infectious disease mitigation in Indigenous populations in the USA and Canada. Infectious disease disparities, driven by persistent inequities in socioeconomic determinants of health, underscore the urgent need for action. We call on governments, public health leaders, industry representatives, and researchers to reject harmful research practices and to adopt a framework for achieving sustainable improvements in the health of Indigenous people that is both adequately resourced and grounded in respect for tribal sovereignty and Indigenous knowledge.

Cancer Progress and Priorities: Gastric Cancer

Gastric cancer, the fifth leading cause of cancer worldwide, is estimated to be responsible for approximately 1.4% of all new cancers and 1.8% of all cancer-related deaths in the United States. Despite declining incidence rates and improved survival rates, however, gastric cancer continues to disproportionately affect racial and ethnic minorities and individuals of lower socioeconomic status at higher rates than the general population. To improve outcomes globally and address disparities within the United States, continued improvements are needed in risk factor modification and biomarker development and to improve access to existing preventative measures such as genetic testing and H. pylori eradication testing, in addition to expanding upon current clinical guidelines for premalignant disease to address gaps in endoscopic surveillance and early detection.

Helicobacter pylori treatment knowledge, access and barriers: A cross-sectional study

BACKGROUND

Helicobacter pylori (Hp) is among the most common bacterial infections in the world and one of the most common infectious agents linked to malignancy, gastric cancer (GC). Within the US there is high disparity in the rates of Hp infection and associated diseases. Hp infection is treatable, and knowledge may influence screening and treatment seeking behaviors.

MATERIALS AND METHODS

In this cross-sectional study of 1042 respondents recruited from the Online Amazon MTurk platform, we sought to assess baseline knowledge of Hp and to gain insight into barriers related to Hp care.

RESULTS

Just over half (52.3%) reported some prior knowledge of Hp with 11.7% (n = 122) reporting being treated for Hp themselves and 21.4% reporting family members diagnosed with Hp. Of respondents reporting prior treatment, 95 (78%) reported GI upset and 27 (21%) reported not completing medications. Specific to Hp and GC, 70% indicated that a belief that the treatment was worse than the symptoms would affect their willingness to seek care, while 81% indicated knowing Hp can cause GC would affect their treatment decisions and knowing their gastric symptoms were caused by Hp would affect their willingness to receive care.

CONCLUSIONS

Knowledge of Hp in this US sample of online respondents is low and self-reported difficulties with treatment compliance is high. Increasing awareness of this infection and addressing the challenges to treatment compliance could potentially reduce rates of Hp antibiotic resistance and progression to GC or other complications of Hp infection.

The Alaska Native Tumour Registry: fifty years of cancer surveillance data for Alaska Native people

Like other Indigenous Circumpolar populations, Alaska Native (AN) people experience different patterns of cancer than their non-Indigenous counterparts. Every 5 years, the Alaska Native Tumour Registry releases a comprehensive report on cancer among AN people; this study provides 50 years of cancer surveillance data. Five-year annual-average age-adjusted incidence rates were calculated for time-periods ranging 1969-2018. AN data were compared with data for US whites (SEER 9). Mortality rates were calculated for 1994-2018 using data from the National Center for Health Statistics. During 2014-2018, there were 2,401 cases of invasive cancer among AN people. Among these, the most commonly diagnosed cancers were colorectal (405 cases, 17% of all cancers), lung and bronchus (373 cases, 16% of all cancers), and female breast (340 cases, 14% of all cancers). Lung cancer was the leading cause of cancer death, followed by colorectal and female breast cancers. These leading cancers are screenable, and preventable through lifestyle modifications including tobacco cessation, healthy eating and engaging in physical activity. These data provide important information to support cancer prevention and control among AN people. Cancer surveillance has been a valuable tool throughout the Circumpolar North to support reducing the burden of cancer among Indigenous populations.Abbreviations: ANAI: Alaska Native/American Indian; AN: Alaska Native; USW: U.S. White(s); ANMC: Alaska Native Medical Center; ANTR: Alaska Native Tumour Registry; IR: Incidence Rate; CI: Confidence Interval; RR: Rate Ratio; ICD-O-3: International Classification of Diseases for Oncology - Third Edition; SEER: Surveillance, Epidemiology and End Results.

Native and Indigenous Populations and Gastric Cancer: A Worldwide Review

Gastric cancer is a worldwide concern, particularly for Indigenous populations who face greater disparities in healthcare. With decreased access to screening and critical treatment delays, this group is experiencing adverse health effects. To determine what factors drive these disparities, a systematic review was performed in PubMed. This revealed a lack of research on gastric cancer specific to this population. The literature primarily focused on subset analyses and biological aspects with sparse focus on determinants of health. The results informed this presentation on factors related to Indigenous gastric cancer, which are influenced by colonialism. Indigenous populations encounter high rates of food shortage, exposure to harmful environmental agents, structural racism in the built environment, H. pylori, and compromised healthcare quality as an effect of colonialism, which all contribute to the gastric cancer burden. Putting gastric cancer into a cultural context is a potential means to respond to colonial perspectives and their negative impact on Indigenous patients. The objective of this manuscript is to examine the current state of gastric cancer literature from a global perspective, describe what is currently known based on this literature review, supplemented with additional resources due to lack of published works in PubMed, and to present a model of gastric cancer through the lens of a modified medicine wheel as a potential tool to counter colonial healthcare perspectives and to honor Indigenous culture.

Helicobacter pylori in Native Americans in Northern Arizona

Background: In Arizona Helicobacter pylori prevalence of infection among Navajo adults is about 62% and gastric cancer incidence rate is 3–4 times higher than that of the non-Hispanic White population. Aim: The aim of this study was to estimate the prevalence of specific H. pylori virulence factors (cagA and vacA) among Navajo patients undergoing and their association with gastric disease. Methods: Virulence genes, cagA and vacA, in H. pylori were investigated in gastric biopsies from 96 Navajo patients over age 18 who were undergoing esophagogastroduodenoscopy. Biopsies from the antrum and fundus were used for molecular characterization to determine cagA type and number of EPIYA motifs and presence of alleles in the signal (s) and medium (m) regions of the vacA gene. Results: H. pylori infection was found in 22.9% of the biopsy samples. The cagA gene amplified in 57.6% of samples and showed a predominant “Western cagA” type, with the EPIYA-ABC motif (45.4%), most prevalent. The vacA allele s1bm1 was the most prevalent (54.5%). Conclusions: H. pylori genotypes were predominantly cagA Western-type and ABC EPIYA motifs. The vacA s1bm1 genotype was the most prevalent and seemed to be associated with gastritis. American Indian/Alaska Native populations are at higher risk for gastric cancer. It is important to identify genotypes of H. pylori and virulence factors involved in the high prevalence of H. pylori and associated disease among the Navajo population.

A Case Control Study of the Seroprevalence of Helicobacter pylori Proteins and Their Association with Pancreatic Cancer Risk

Background: The association between Helicobacter pylori (H. pylori) infection and pancreatic cancer (PC) risk remains inconclusive. We examined the association between H. pylori antibodies and PC risk in a case-control study at a comprehensive cancer center.

Methods: Multiplex serology using a glutathione S-transferase capture immunosorbent assay in conjunction with fluorescent bead technology was used to measure antibodies to 15 H. pylori proteins in serum or plasma from 131 incident cases with PC or a PC precursor and 131 healthy controls. Reactivity to ≥4 H. pylori proteins was defined as the overall seroprevalence. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), with adjustment for age at diagnosis/interview, gender, and race.

Results: The majority of the sample was 50 years or older, and from the white race group. Half of the sample were women. Seroprevalence ≥4 of H. pylori proteins was 11.1%. Overall, H. pylori seroprevalence was not associated with PC risk (OR: 0.59; 95% CI: 0.25–1.40). The prevalence of several H. pylori-specific proteins HP537 (OR: 1.78; 95% CI: 0.30–10.51), HP305 (OR: 1.38; 95% CI: 0.61–3.16), and HP410 (OR: 1.31; 95% CI: 0.44–3.96) increased the odds of PC. Similarly, H. pylori-specific proteins HP522 (OR: 0.25; 95% CI: 0.04–1.66), HyuA (OR: 0.49; 95% CI: 0.21–1.14), and HP1564 (OR: 0.63; 95% CI: 0.27–1.51) decreased the odds of PC. However, these findings were not statistically significant at α = 0.05.

Conclusions: Our findings do not support an association between H. pylori and PC risk. Further evaluation of this lack of association is recommended.

The prevention of gastric cancer by Helicobacter pylori eradication

PURPOSE OF REVIEW

Gastric cancer remains one of the most common causes of death globally. Increasing evidence suggests that many gastric cancer cases can be prevented by eradicating its most important etiological agent, Helicobacter pylori. Using the search terms 'H. pylori' and 'gastric cancer' we reviewed the scientific literature regarding the association between H. pylori and gastric cancer published from 1 January 2020 to 30 May 2021. We review the most important articles relevant to the clinical issues regarding H. pylori eradication for gastric cancer prevention.

RECENT FINDINGS

In randomized trials, eradication of H. pylori is associated with an approximately 50% reduction in sporadic gastric cancer. A similar benefit was observed when screening first-degree relatives of gastric cancer cases, after resection of early gastric cancer to prevent metachronous neoplasia, and in population-based screen and treatment programs in areas of high H. pylori and gastric cancer prevalence. Even in relatively low gastric cancer countries such as the United States, gastric cancer may potentially be avoided by screening for H. pylori, especially among minority groups who are at greatest risk.

SUMMARY

Gastric cancer is preventable, at least in part, by H. pylori eradication. Ongoing screening trials will help determine whether population-based H. pylori screening programs are feasible and cost-effective. Their results are likely to differ according to H. pylori and gastric cancer prevalence rates.

Recent advances in immune therapies for gastric cancer

Gastric cancer (GC) is an aggressive malignancy that is the third leading cause of cancer mortality worldwide. Localized GC can be cured with surgery, but most patients present with more advanced non-operable disease. Until recently, treatment options for relapsed and refractory advanced GC have been limited to combination chemotherapy regimens, HER-2 directed therapy, and radiation, which lead to few durable responses. Over the past decade, there have been significant advances in our understanding of the molecular and immune pathogenesis of GC. The infectious agents Epstein-Barr virus and Helicobacter pylori perturb the gastric mucosa immune equilibrium, which creates a microenvironment that favors GC tumorigenesis and evasion of immune surveillance. Insights into immune mechanisms of GC have translated into novel therapeutics, including immune checkpoint inhibitors, which have become a treatment option for select patients with GC. Furthermore, chimeric antigen receptor T-cell therapies have emerged as a breakthrough treatment for many cancers, with recent studies showing this to be a potential therapy for GC. In this review, we summarize the current state of knowledge on immune mechanisms of GC and the status of emerging immunotherapies to treat this aggressive cancer, as well as outline current challenges and directions for future research.

Gastric Cancer in Alaska Native and American Indian People Living in Alaska, 1990-2017

INTRODUCTION

Alaska Native (AN) people experience a high burden of gastric cancer compared with other US Native and non-Native populations. Previous reports have suggested that gastric cancer in AN people occurs at a younger age and is a more aggressive pathologic type. We evaluated all cases of gastric cancer in AN people from 1990 to 2017 and compared the epidemiologic and pathologic characteristics with the gastric cancers that occurred in the same time in the US white (USW) population.

METHODS

Cancer data were collected by the Alaska Native Tumor Registry and National Cancer Institute's Surveillance, Epidemiology, and End Results Program. Comparisons were performed looking at the age and sex distribution of the affected AN and USW people, as well as the cancer characteristics, including the location, stage, and pathology.

RESULTS

The age distribution was significantly different between AN and USW patients (P < 0.001), with a greater proportion of AN people diagnosed younger than 40 years (11% vs 3%, P < 0.0001) and 40-59 years (37% vs 20%, P < 0.0001). In addition, a greater proportion of AN people were diagnosed with distant stage cancer (AN: 48% and USW: 35%, P < 0.0001). The age-adjusted rate of gastric cancer in the AN population was significantly higher than the USW population (20.8 vs 6.7 per 100,000 persons, P < 0.0001). Although there has been a significant decrease in the gastric cancer incidence rate in the USW population, no significant change in incidence was seen in the AN population.

DISCUSSION

This study highlights the disproportionate burden of gastric cancer in the AN population. Further work is needed to address and understand this disparity.

Stomach Cancer Incidence and Mortality Trends among Circumpolar Nations

BACKGROUND

Stomach cancer incidence and mortality rates are declining across circumpolar nations, but the burden may not be distributed equally across subpopulations, including Indigenous peoples. Our objective was to examine stomach cancer incidence and mortality trends across circumpolar populations.

METHODS

Cancer incidence and mortality data from 1999-2016 were obtained from the Canadian Cancer Registry, Canadian Vital Statistics, CDC WONDER, NORDCAN, Northwestern Russian cancer registries, and National Cancer Reports. The direct method was used to calculate 10-year rolling age-standardized incidence and mortality rates to the world (WHO 2000-2025) and 2011 Canadian standard populations. Standardized incidence rate ratios (SRR) were calculated. Data were stratified by sex, year, and region. U.S. data were broken down by race [White; American Indian/Alaska Native (AIAN)]. Race data were not available from non-U.S. cancer registries.

RESULTS

Most populations showed declining incidence and mortality rates over time. Incidence rates among Greenland males and females, Alaska AIAN males and females, and Northern Canadian both sexes were elevated compared with regional counterparts and remained stable. The largest male SRR was observed among Alaska AIAN versus Alaska Whites [SRR = 3.82; 95% confidence interval (95% CI), 2.71-5.37]. The largest female SRR was observed among Alaska AIAN versus Alaska Whites (SRR = 4.10; 95% CI, 2.62-6.43).

CONCLUSIONS

Despite stomach cancer incidence and mortality rates declining overall, some northern and Indigenous populations experience elevated and stable incidence and mortality rates.

IMPACT

There is a need to address disparities observed among circumpolar subpopulations. Given similarities in incidence, mortality, and risk factor prevalence across circumpolar regions, addressing disparities could benefit from coordinated international action.