Wood cookstove use is associated with gastric cancer in Central America and mediated by host genetics

Population-Based Study of Gastric Cancer Survival and Associations in Rural Western Honduras

BACKGROUND

Two-thirds of global cancers occur in low/middle income countries (LMIC). Northern Central America is the largest LMIC region in the Western Hemisphere and lack cancer registries to guide cancer control. We conducted a gastric cancer survival study in rural Western Honduras, characterized as having among the highest gastric cancer incidence rates in Latin America.

METHODS

The cohort of incident gastric cancer diagnosed between 2002 and 2015 was studied with active follow-up with household visits. The regional gastric cancer registry was primary for case identification, with completeness examination with hospital data and national death certificates. Cox regression models were used for survival calculations.

RESULTS

Survival follow-up was achieved in 741/774 patients (95.7%). Household interviews were conducted in 74.1% (n = 549); 65.7% were male, median age at diagnosis was 64 years, 24.5% were <55 years; 43.9% of tumors had pyloric obstruction; 45.2%, 43.2%, and 7.3% of histology was intestinal, diffuse, and mixed, respectively. A total of 24.7% patients received treatment. The 5-year survival rates were 9.9% for both males and females, 7.7% for age <45, and 7.9% for diffuse gastric cancer. Median survival time was 4.8 months [95% confidence interval (CI), 4.2-5.6]. In the final Cox regression model including age, sex, Lauren subtype, and poverty index, only treatment was significantly associated with survival (hazard ratio = 2.43, 95% CI, 1.8-3.2).

CONCLUSIONS

Markedly low gastric cancer 5-year survival rates are observed in rural Central America. The majority of patients present with advanced disease and a minority have access to therapy.

IMPACT

The findings have implications for cancer control in the Central America LMICs and for US Latino populations. See related commentary by Riquelme and Abnet, p. 1550.

High Incidence of Gastric Cancer in El Salvador: A National Multisectorial Study during 2000 to 2014

BACKGROUND

Gastric adenocarcinoma is the fourth leading cause of global cancer mortality and leading infection-associated cancer. Gastric cancer has significant geographic variability, with a high incidence in East Asia and mountainous regions of Latin America. In the United States, gastric cancer represents a marked disparity with incidence rates that are two to three times higher in Hispanics compared to non-Hispanic Whites.

METHODS

We conducted a national retrospective study of incident gastric cancer in El Salvador from to 2000 to 2014 to estimate the age-standardized incidence rate (ASIR) by using a combination of pathology and endoscopy databases. A unique multisectorial coalition was formed between the Ministry of Health (MINSAL) and ES Gastroenterology Society (AGEDES), representing public hospitals (n = 5), governmental employee hospitals (ISSS, n = 5), and private facilities (n = 6), accounting for >95% of national endoscopy capacity. HER2 and EBV tumor status was ascertained in a representative sample during 2014 to 2016.

RESULTS

A total of 10,039 unique cases of gastric cancer were identified, 45.5% female, and mean age of 65. 21% and 9.4% were <55 and <45 years old, respectively. ASIRs (M, F) were 18.9 (95% CI, 14.4-20.7) and 12.2 per 100,000 persons (95% CI, 10.9-13.5), respectively, in the period 2010 to 2014 with all centers operational. Intestinal gastric cancer was 2.8 times more common than diffuse gastric cancer; 23.2% had partial or complete pyloric obstruction. The HER2 2+/3+ status was 16.7% and EBV-encoded RNA positivity was 10.2%.

CONCLUSIONS

A high incidence of gastric cancer was confirmed in El Salvador and nearly half of the patients were female.

IMPACT

The findings have implications for cancer control in the Central America LMICs and for US Latino populations. See related commentary by Riquelme and Abnet, p. 1550.

The Burden of Gastric Cancer in Northern Central America

Gastric cancer is the fourth leading cause of cancer-related death worldwide, with nearly one million new cases diagnosed in 2020. There is marked variation in gastric cancer incidence globally, with highest incidence rates reported in the United Nations regions of Eastern Asia, Eastern Europe, and Latin America. Although the United States is considered a low-incidence country, gastric cancer presents an important cancer disparity, with higher incidence in minoritized populations, including immigrants from high-incidence regions. The Northern Central America nations are low- and middle-income countries with a high gastric cancer incidence and large US immigrant populations. These countries lack comprehensive cancer registries, but recent GLOBOCAN-imputed gastric cancer estimates are in the range of 8 to 12/100,000 age-standardized incidence rates. Three epidemiologic studies carried out in El Salvador, Nicaragua, and Honduras demonstrate a higher than predicted burden of gastric cancer with low 5-year survival (<10%). The gastric cancer burden is projected to increase in the absence of changes to national and regional cancer control plans. Twelve evidence-based recommendations to reduce gastric cancer mortality in the Americas have recently been proposed, ranging from the "test-and-treat" Helicobacter pylori eradication strategy to endoscopic screening and surveillance programs. Translating these recommendations into a practical plan for this resource-limited setting could address the disproportionate gastric cancer burden. See related article by Peña-Galo et al., p. 1564 See related article by Ruiz de Campos et al., p. 1571 See related article by Dominguez et al., p. 1578.

Differences in Prevalence of Histologic Gastric Cancer Subtypes Between Mestizo and Mayan Populations in Guatemala

PURPOSE

Although the intestinal subtype of gastric cancer (GC) is most prevalent around the world, a relatively high prevalence of the diffuse subtype has been reported in some populations of Central American countries, including Guatemala. This study aimed to investigate whether differences exist in the prevalence of the two GC subtypes in the two main ethnic groups in Guatemala, namely Mayan and Mestizo (known as Ladino in Guatemala), between whom significant socioeconomic disparities exist, and to determine whether there is an association with Helicobacter pylori/CagA seropositivity.

MATERIALS AND METHODS

Participants included 65 patients with GC and 135 age-/sex-matched controls. Data on ethnicity, H. pylori and CagA seropositivity status, as well as tumor subtype (diffuse or intestinal) were collected. Logistic regression models were fitted to examine the relationship between predictor variables (age, sex, ethnicity, H. pylori, and CagA) and the binary response variable (tumor type). Model selection was based on the Akaike information criterion.

RESULTS

The prevalence of diffuse GC was found to be significantly higher in the Mayan compared with the Mestizo population in Guatemala. Although seropositivity for CagA was significantly higher in patients with GC, there were no significant differences between the two GC subtypes.

CONCLUSION

This study suggests that there are differences in the prevalence of intestinal and diffuse GC histologic subtypes between the two main ethnic groups in Guatemala. Further studies are warranted, given the potential higher prevalence of the more severe GC subtype in the most vulnerable population.