Gastric cancer: a neglected threat to racial and ethnic minorities in the USA

The COVID-19 pandemic in the USA has exposed the pervasive inequities in health care for racial and ethnic minority groups. Health-care professionals, especially those focused on cancer prevention and early detection, were aware of this inequity before the pandemic. But, COVID-19 has amplified the racial and ethnic health-care inequities that exist in an infrastructure that was not built to bridge these gaps, and now finds itself under pressure from an unprecedented global health crisis. Calls to rectify disparities in early cancer detection and prevention efforts are reassuring, particularly since it is anticipated that these will deepen without immediate action.¹ However, these calls have primarily focused on cancers for which systematic screening recommendations already exist, such as colorectal cancer and breast cancer. There is one cancer in particular that regrettably continues to get little attention, despite being defined by striking racial and ethnic disparities in the USA: gastric cancer.

Gastric cancer disproportionately affects non-White racial and ethnic minority groups in the USA, especially non-Hispanic Black Americans, Hispanic Americans, Asian Americans, and other immigrant groups coming from countries with a high incidence of gastric cancer. A recent US population-based analysis quantified this disproportionate risk, reporting that, among the age group generally considered for cancer screening (age ≥50 years), there is an up to 14·5-times higher risk of non-cardia gastric adenocarcinoma—the most common form of gastric cancer—in non-White racial or ethnic groups compared with non-Hispanic White people.² In fact, the age-adjusted incidence of gastric cancer is markedly higher than oesophageal cancer in all non-White racial or ethnic groups (appendix), and even exceeds that of colorectal cancer in certain groups (eg, Korean American men). Importantly, these comparisons probably underestimate the true burden of disease since early gastric cancer typically goes undiagnosed in the USA in the absence of systematic screening programmes.

In the USA, guidelines clearly delineate which populations are recommended to undergo screening for colorectal and oesophageal cancers. And, because there are guidelines, these preventive interventions are typically covered by insurance. Gastric cancer screening does not have such guidelines and insurance coverage, despite substantial evidence identifying high-risk groups and decision model analyses showing that endoscopy for gastric cancer screening in these high-risk groups could be cost-effective.³ Reflecting the mismatch between high disease burden in specific populations and inadequate cancer-attenuating efforts, the norm in the USA is that gastric cancer is diagnosed in more advanced stages when symptoms prompt diagnostic investigations. When diagnosed in these late stages, there are no curative options and the prognosis is dismal; this should not be the norm. In countries where gastric cancer screening programmes exist, gastric cancer is more often diagnosed in an early (typically asymptomatic) stage before submucosal invasion, when endoscopic or surgical resection can be done with curative intent and is associated with greater than 95% 5-year survival.⁴ According to modelling studies, the cost benefit of gastric cancer screening in the USA is predominantly driven by the increased probability of diagnosing gastric neoplasia at a stage when resection is typically curative.³ Moreover, there have been remarkable strides in advanced endoscopic expertise. Indeed, endoscopic resection of early gastric cancer is increasingly available in the USA,⁵ and achieves similar outcomes as in the east Asian countries that pioneered and perfected these techniques. In fact, these techniques were borne in response to, and in parallel with, the increased number of early gastric cancer cases being diagnosed as a result of implementing national gastric cancer screening programmes in Japan and South Korea.

Thus, a convincing argument can be made that gastric cancer early detection and prevention programmes in the USA are overdue. We have evidence suggesting that non-White racial and ethnic groups in the USA bear a disproportionate burden of gastric cancer and at a rate that sometimes exceeds that of cancers for which screening currently occurs. There is evidence that endoscopic screening for gastric cancer is associated with substantially improved gastric cancer-related mortality in countries where gastric cancer screening already occurs. The USA also has the infrastructure, technology, expertise, and resources to appropriately manage the expected increase in the number of gastric cancer diagnoses that would result from systematic screening. No doubt, randomised controlled trials in the USA comparing the effectiveness of screening versus no screening on gastric cancer incidence and mortality would provide the strongest level of direct evidence. The USA has an established track record of implementing large-scale longitudinal screening trials for colorectal, breast, lung, and ovarian cancers to generate the amount of actionable evidence needed to inform screening recommendations for these cancers. Yet, there are currently no trials to test gastric cancer screening versus no screening in the USA (according to ClinicalTrials.gov), despite the clear capability and need to do such trials. The fact that colorectal cancer screening guidelines were extended by some societies to now recommend that screening initiation occur at age 45 years instead of 50 years in all average-risk US residents based solely on modelling studies, as opposed to data from robust clinical trials, further highlights the disparity between gastric cancer and other cancers when it comes to attenuation efforts.

The USA is becoming increasingly racially and ethnically diverse and enriched with populations at elevated risk for gastric cancer. Immigrants and their descendants are expected to account for nearly 90% of the anticipated population growth through to 2065, with Asian and Hispanic American populations expected to surpass the non-Hispanic White population in the USA by that time. So, with all the calls to action for cancer prevention equity, what is needed now more than ever is a call to action for gastric cancer specifically. It is not enough to acknowledge the racial and ethnic group differences that define gastric cancer in the USA. If current complacency continues, gastric cancer disparities will inevitably worsen, and will be further promulgated by the disproportionate effect on racial and ethnic minorities that the COVID-19 pandemic has unleashed.