Benefits of H. pylori eradication in preventing gastric cancer in the older population: results from a population-based study

Abstract

Introduction: Although H. pylori (HP) eradication has been shown to reduce the risk of gastric cancer development, it remains elusive whether there is a point of no return on the HP-associated gastric carcinogenesis cascade. In particular, there are limited data on the benefits of HP eradication on gastric cancer prevention in the older population ( 60 years). Aims & Methods: We aimed to compare the age-specific risk of gastric cancer development in a large cohort of HP infected subjects who had received HP eradication therapy with the local general population. Methods: The results were based on a retrospective cohort study that included all HP-infected subjects who had received a 7-day course of clarithromycin-based triple therapy between 2003 and 2012 in Hong Kong. These subjects were identified from a territory-wide health database, which captured all patients’ clinical information in the local public health care system. We excluded subjects with history of gastrectomy, were diagnosed to have gastric cancer prior to or within 12-month of HP therapy, and those who failed clarithromycin-based triple therapy. Person-years at risk were derived for each patient from the first date of HP therapy until the date of gastric cancer diagnosis, death or the date of censoring. Expected number of gastric cancer cases in the general population were estimated on data from the population-based Hong Kong Cancer Registry. We determined the standardized incidence ratio (SIR) of the HP eradicated cohort and the general population of the same age group which included both HP-infected and non-infected subjects. All analyses were conducted by a priori age groups of 540, 40–59.9 and 60 years. Results: Among the 63,397 eligible HP-infected subjects (median age 54.0 years, 46.5% male) who had received clarithromycin-based triple therapy, 153 (0.2%) developed gastric cancer with a median follow-up of 7.4 years (overall incidence: 3.2 per 10,000 person-years). The cumulative gastric cancer incidence rates in the HP-eradicated cohort at 12 years were 0.1%, 0.3% and 0.8% for the540, 40–59.9 and 60 years groups, as compared to 0.1%, 0.3% and 1.1% for the estimated cumulative incidence rates in the matched age groups of the general population. Among the 60 years group, the risk of gastric cancer was significantly lower in the HP eradicated group as compared to the general population (SIR¼0.75; 95% CI, 0.61 to 0.92), corresponding to a 25% reduction in gastric cancer incidence. In contrast, the corresponding SIR was 1.37 (95% CI, 0.43 – 3.30) in the540 years and 1.07 (95% CI, 0.82 – 1.38) in the 40–59.9 years groups. Conclusion: In this large population-based study of HP-eradicated subjects, we found that the risk of gastric cancer was significantly lower among those who received HP eradication at 60 years than the age-matched general population. Our results suggest benefits of HP eradication on gastric cancer prevention even in the aged population.