Endoscopic yield of chronic dyspepsia in outpatients: A single-center experience in Cambodia.

BACKGROUND AND AIM: The diagnostic evaluation and management of patients with chronic dyspepsia may differ geographically according to patient age, prevalence of Helicobacter pylori or parasitic infection, and risk of gastric cancer. The characteristics and appropriate investigation of Cambodian patients with dyspepsia have not previously been studied. The aim of this study was to investigate the characteristics of Cambodian patients with chronic dyspepsia, the yield of upper endoscopy in these patients, and the value of alarm features in identifying patients with organic causes of dyspepsia. METHODS: We conducted a retrospective, single-center study of 1231 adults with chronic dyspepsia who underwent upper endoscopy. We compared clinical characteristics, H. pylori prevalence, and endoscopic and histological findings of patients with functional or organic causes of dyspepsia. This study was approved by the National Ethics Committee for Health Research. RESULTS: The majority of patients had overlapping symptoms of epigastric pain/burning and postprandial fullness/early satiety (40.6%), followed by epigastric pain/burning alone (29.7%) and postprandial fullness/early satiety alone (29.7%). Organic lesions were diagnosed in 6.9% of patients. The overall prevalence of H. pylori infection was 46% and was similar in the three clinical subgroups. The sensitivity and specificity of alarm features for organic causes of dyspepsia were 14 and 96%, respectively. The majority of patients with gastric cancer were 40 years of age or older. CONCLUSIONS: The majority of patients with chronic dyspepsia seen at our outpatient center were diagnosed with functional or H. pylori-associated dyspepsia. The presence of alarm features was not sensitive or specific for differentiating organic and functional dyspepsia.

Expansion of European vacA and cagA alleles to East-Asian Helicobacter pylori strains in Cambodia.

Helicobacter pylori infection is associated with gastric cancer (GC). The highest incidence rates have been described in Asia, but regional variations exist that do not match the distribution of infection prevalence rates. The aim of the study was to examine the possible contribution of H. pylori virulence factors to geographic differences in the incidence of GC across East and Southeast Asia. We studied 66 isolates from Cambodian patients that had previously been assigned to two genetic populations based on sequences of seven housekeeping genes, namely hpEurope (n = 34, 51.5%) and hpEastAsia, subpopulation hspEAsia (n = 32, 48.5%). These strains were characterized with respect to vacA polymorphism and cagA status by PCR, and the CagA C-terminal region was sequenced. We also sequenced the complete cagA gene from 10 hpEurope and 10 hspEAsia strains chosen at random. The cagA gene was present in 92.4% of the 66 isolates and was mainly of Western type (n = 36, 59.0%). hspEAsia strains carrying East-Asian CagA and the m1-type vacA allele (15.2%) were less frequent among the 66 Cambodian isolates than reported in East Asian countries, a finding that might partly explain the intermediate incidence of GC in Cambodia, and by extension, in Southeast Asia (except for Vietnam). The observed high prevalence of s1a alleles (34.4%) and Western CagA (28.1%) among hspEAsia strains indicates frequent introgression of European vacA and cagA alleles into East Asian H. pylori strains. This expansion might have severe consequences for individual disease outcome.

Evolutionary history of Helicobacter pylori sequences reflect past human migrations in Southeast Asia.

The human population history in Southeast Asia was shaped by numerous migrations and population expansions. Their reconstruction based on archaeological, linguistic or human genetic data is often hampered by the limited number of informative polymorphisms in classical human genetic markers, such as the hypervariable regions of the mitochondrial DNA. Here, we analyse housekeeping gene sequences of the human stomach bacterium Helicobacter pylori from various countries in Southeast Asia and we provide evidence that H. pylori accompanied at least three ancient human migrations into this area: i) a migration from India introducing hpEurope bacteria into Thailand, Cambodia and Malaysia; ii) a migration of the ancestors of Austro-Asiatic speaking people into Vietnam and Cambodia carrying hspEAsia bacteria; and iii) a migration of the ancestors of the Thai people from Southern China into Thailand carrying H. pylori of population hpAsia2. Moreover, the H. pylori sequences reflect iv) the migrations of Chinese to Thailand and Malaysia within the last 200 years spreading hspEasia strains, and v) migrations of Indians to Malaysia within the last 200 years distributing both hpAsia2 and hpEurope bacteria. The distribution of the bacterial populations seems to strongly influence the incidence of gastric cancer as countries with predominantly hspEAsia isolates exhibit a high incidence of gastric cancer while the incidence is low in countries with a high proportion of hpAsia2 or hpEurope strains. In the future, the host range expansion of hpEurope strains among Asian populations, combined with human motility, may have a significant impact on gastric cancer incidence in Asia.

Colorectal cancer in young Cambodians.

AIM: Colorectal cancer (CRC) is a common disease in the older population, but it has become increasingly evident that it is also not infrequent in the young. The aim of this study was to describe the epidemiological, clinical and pathological characteristics of CRC in young Cambodians. METHODS: We examined clinical and pathological data from all CRC cases registered in the two reference centres for gastrointestinal tumours in Cambodia between 2005-2010. Age-specific CRC incidence rates were computed using the national population census 2008 data from the National Institute of Statistics. We compared differences in distribution of tumour location, histology, differentiation and UICC/TNM stage in two age groups, namely < 40 and ≥ 40. RESULTS: During this period, there were 356 new CRC cases, of which 29.8% affected patients younger than 40. This proportion is the second highest in the world, with a higher proportion only reported in Egyptian population. The crude incidence was 2.82 and 2.36 per 100,000 in females and males, respectively. Adenocarcinoma was the most common histologic type, and >50% of all tumours occurred in the colon, with no appreciable variation between the two age groups. Mucin-producing and advanced-grade tumours were twice more frequent in the young. CONCLUSION: The unusually high CRC proportion in the young in our study could be due to referral bias. Nevertheless, together with the continuous exposure to hazardous environmental agents and the prevalent consanguinity in Cambodia, this question warrants further research to advance our understanding of CRC risk factors and perhaps genetic-environmental interactions in CRC epidemiology in young adults.