Clinical FeaturesEndocrine/MetabolicGastroenterology

Developments in Gastric Cancer Screening in Europe

The current state of play: Gastric Cancer in Europe

In 2020, gastric cancer stood as the 6th most commonly diagnosed cancer, with 136,000 new cases diagnosed in Europe alone. Overall, Europe hosts the second-highest incidence of gastric cancer worldwide. While classically associated with Asian countries, European countries such as Portugal, Estonia, and Latvia report age-standardized rates comparable to China.

Although the overall incidence of gastric cancer has declined in the past decade, the absolute number of new cases is anticipated to rise as the ageing population grows. In Ireland, the National Cancer Registry has captured approximately 600 new cases of gastric cancer per year (data from 2014.-2021), placing Irish males in the ‘intermediate risk’ category for gastric cancer.

Unfortunately, gastric cancer still carries an extremely poor prognosis in Europe as it is frequently diagnosed at an advanced stage. Approximately two-thirds of Irish patients have stage 3 or 4 cancer at diagnosis, with an average 5-year survival rate of only 24%. In contrast, Japan, which has one of the highest incidences of gastric cancer worldwide, has implemented a successful screening program, which has resulted in a 5-year survival rate of up to 58%.

Gastric Cancer Screening and Europe’s Beating Cancer Plan

In 2022, the European Commission published ‘Europe’s Beating Cancer Plan’. This report identified three cancers to target for the development of new national screening programmes: gastric, lung and prostate cancer.

However, as it stands, the most cost-effective and feasible method of gastric cancer screening in a European population is largely unknown. Therefore, in response to the recommendations from the European Commission on gastric cancer screening, a research group known as TOGAS (Towards Gastric Cancer Screening Implementation in the European Union) was established. This group involves 20 partners across 14 different EU countries. This group will conduct three pilot projects funded by the European Union to provide initial data on the feasibility and cost-effectiveness of different screening methods in order to address this unknown.

Ireland is one of the countries involved in the study and represents countries in Europe with a low-intermediate risk of gastric cancer. The Irish TOGAS team is being led by Professor Colm O’Morain, Clinical Lead in Gastroenterology & Hepatology and co-researchers Dr Orlaith Kelly, Consultant Gastroenterologist, Connolly Hospital and Dr Charlene Deane, Specialist Registrar in Gastroenterology. Having paired with Centric Healthcare, the Irish Defence Forces, the Construction Workers Health Trust and the Beacon HealthCheck, they will offer invitations to 30-34 year olds to be screened for Helicobacter pylori as part of pilot 1, a primary preventative strategy to gastric cancer.

Screening mechanisms and existing Screening Programmes

Pathogenesis of Gastric Cancer

The Correa cascade defines the pathogenic progression from normal mucosa to atrophic gastritis, gastric intestinal metaplasia, low-grade dysplasia, high-grade dysplasia, and, ultimately, carcinoma. Screening is focused on the disruption this cascade through early detection and treatment of Helicobacter pylori, a known promoter of preneoplastic and neoplastic lesion development, known as primary prevention. Secondary prevention involves the early detection of precancerous and early cancerous lesions. Both approaches aim to intervene at a point where pharmacological or endoscopic intervention can effectively stop progression through this pathway thereby reducing unnecessary cancer deaths.

While no gastric cancer screening programme currently exists in Europe, the concept is not new. The Maastricht VI/ Florence consensus guidelines, the Science Advice for Policy by European Academics (SAPEA), and the International Agency for Research on Cancer (IARC) all recommend a ‘screen and treat’ approach in countries in Europe with intermediate and high risk of gastric cancer. Meanwhile, screening programmes have already been effectively implemented in several Asian countries for decades. The earliest gastric cancer screening programme was established in Japan in the 1950s. Since then, numerous randomised controlled trials have been conducted to evaluate the impact of primary and secondary prevention screening strategies on mortality rates.

Evidence Supporting Primary Prevention

Several randomised control trials have demonstrated the advantage of population screening and treatment of H.pylori in reducing gastric cancer risk. Ford et al. conducted a meta-analysis encompassing seven randomised control trials involving healthy adults with H.pylori infection who received either treatment or a placebo. The pooled analysis revealed an impressive relative risk reduction in gastric cancer mortality for those receiving treatment (RR 0.54; 95% CI 0.400.72), with little heterogeneity among the studies. According to this meta-analysis, the calculated number needed to treat to prevent one case of gastric cancer was 72, and the number needed to treat to prevent one cancerrelated death was 135. Numerous longitudinal observational studies also support the positive impact of population screening. The Matsu Island study, a notable prospective investigation, involved testing and treating adults over 30 for H.pylori. The study reported a 53% reduction in gastric cancer incidence, a 25% reduction in mortality, and no increase in the antibiotic resistance rate of H. pylori. In a specific examination of a European population, Doorakkers et al. utilised the Swedish National database to assess the impact of H.pylori treatment on gastric cancer incidence, once again confirming the benefits of eradication in reducing mortality. Lastly several randomised control trials with long-term follow-up are underway, with planned analyses in the near future. One of these longitudinal studies being conducted in the UK is the ‘The Helicobacter pylori screening study’ currently due for completion in 2024.

Evidence Supporting Secondary Prevention

Secondary preventive measures as part of national screening programme have included endoscopy, photofluorography and/or serum pepsinogen levels to identify early neoplastic lesions. The evidence to date is predominantly based in Asian countries and strongly supports good quality endoscopy as the superior screening method out of these three. A recent metaanalysis by Hibino et al. reported a 48% relative risk reduction in gastric cancer mortality among individuals who underwent endoscopic screening. A more targeted screening approach in Europe using secondary screening modalities has also been proposed in several smaller-scale studies.

Three particular studies in a European population include those performed by Planade, Segrad and Tepes et al. in France, Germany and Slovenia, respectively. In these studies, they reported findings on gastroscopy of those undergoing a colonoscopy as part of their national screening service.

These studies were performed to determine if concurrent gastroscopy with colonoscopy would benefit this ‘high-risk’ age group. These studies had a positive diagnostic yield of precancerous lesions ranging from 6.4–30% and H.pylori infection ranging from 17-75%.

Future Direction and ongoing research

European-funded research into screening strategies is ongoing both as part of the Eurohelican study, which looks at the feasibility of a national screening programme for H. pylori in Slovenia and the TOGAS study. We can expect the results to be published in 2026, and the outcomes will help determine future policy-making decisions on a gastric cancer screening approach.

Other areas of research which may positively impact screening strategies in the future include the ongoing research into the potential of engineered probiotics which target H.pylori, vaccination against H.pylori which currently remains at a preclinical stage and the drive to improve quality in upper gastrointestinal endoscopy through the use of artificial intelligence.

“Funded by the European Union. Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union. The European Union cannot be held responsible for them.”

Written by Dr Charlene Deane, Dr Orlaith Kelly and Professor Colm O’Morain

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