Increased risk of Helicobacter pylori associated with birth in wartime and post-war Japan

LNT and cancer risk assessment: Its flawed foundations part 1: Radiation and leukemia: Where LNT began

This paper evaluates the scientific basis for the adoption of the linear non-threshold (LNT) dose response model for radiation-induced leukemia. This LNT risk assessment application for leukemia is significant because it: (1) was generalized for all tumor types induced by ionizing radiation and chemical carcinogens at relatively high doses and; (2) it was based on the mechanistic assumption of low dose linearity for somatic cell mutations as determined from responses in mature spermatozoa of fruit flies. A serious problem with the latter assumption is that those spermatozoa lack DNA repair. The acceptance of the LNT dose response model for cancer risk assessment was based on the convergence of recommendations of the BEAR I Genetics Panel (1956a) for reproductive cell gene mutations and those of Lewis (1957a) for somatic cell mutation and its capacity to explain apparent and/or predicted linear dose responses of ionizing radiation-induced leukemia in multiple and diverse epidemiological investigations. Use of that model and related dose response beliefs achieved rapid, widespread and enduring acceptance in the scientific and regulatory communities. They provide the key historical foundation for the sustained LNT-based policy for cancer risk assessment to the present. While previous papers in this series have challenged key scientific assessments and ethical foundations of the BEAR I Genetics Panel, the present paper provides evidence that Lewis: 1) incorrectly interpreted the fundamental scientific studies used to support the LNT conclusion even though such studies show consistent hormetic-J-shaped dose response relationships for leukemia in Hiroshima and Nagasaki survivors; and, 2) demonstrated widespread bias in support of an LNT conclusion and related policies, which kept him from making an objective and fair assessment. The LNT recommendation appears to have been uncritically accepted and integrated into scientific and regulatory practice in large part because it inappropriately appealed to existing authority and it garnered the support of those who were willing to risk greatly exaggerating the public's fears of environmentally-induced disease, such as enhanced risk of leukemia, with the goal of stopping the atmospheric testing of atomic bombs. Adoption of the LNT recommendation demonstrated extensive penetration of ideological influence affecting governmental, scientific and regulatory evaluation at the highest levels in the United States. This paper demonstrates that the scientific foundations for cancer risk assessment were inappropriately and inaccurately assessed, unethically adopted and require significant historical, scientific and regulatory remediation.

Helicobacter pylori: History and facts in Peru

Helicobacter pylori (H. pylori) is a cosmopolite bacteria and the main responsible for the high burden of gastric cancer in developing countries, such as Peru. In this review, we describe some historical facts in the H. Pylori discovery, the first researches of this bacterium in Peru, as well as its epidemiology, clinical characteristics, diagnosis, treatments, and outcomes. Our literature and review of real-life data suggest that several efforts should be conducted in our country to deal with antibiotic-resistance and lack of adherence to treatment in order to reduce our incidence of gastric cancer.

Gastric Cancer Mortality Trends in Tuscany, Italy, 1971–2004

Aims, Background, and Methods

In Tuscany, Italy, gastric cancer mortality has been decreasing since 1950, although with relevant geographical variability across the region. In Eastern Tuscan areas close to the mountains (high risk areas), gastric cancer mortality has been and is still significantly higher than that recorded in Western coastal areas and in the city of Florence (low risk areas). High-risk areas also showed higher Helicobacter pylori seroprevalence. Aim of this paper is to study gastric cancer mortality trends in high and low-risk areas, during the period 1971–2004, using age-period-cohort models.

Results

In high-risk areas, gastric cancer mortality rates declined from 61.4 per 100,000 in 1971–74 to 19.8 in 2000–2004 and in low-risk areas from 34.9 to 9.8. Mortality decline in high-risk areas was mainly attributable to a birth cohort effect, whereas in low-risk areas it was due either to a birth cohort effect or a period effect. In low- and high-risk areas, birth-cohort risks of dying decreased over subsequent generations, except for the birth cohorts born around the second world war.

Conclusions

Gastric cancer mortality in areas with higher H. pylori seroprevalence in Tuscany (high-risk areas) showed a predominant decline by birth cohort, in particular for younger generations, possibly due to the decrease of the infection for improvement of living conditions.

Changing trends in the prevalence of H. pylori infection in Japan (1908-2003): a systematic review and meta-regression analysis of 170,752 individuals

Changing trends in the prevalence of H. pylori infection in the general population over time are thought to be the main driving force behind the declining gastric cancer mortality in Japan. However, whether the prevalence of H. pylori infection itself shows a birth-cohort pattern needs to be corroborated. We performed a systematic review of studies that reported the prevalence of H. pylori infection among Japanese individuals. Meta-regression was conducted in the framework of a generalized additive mixed model (GAMM) to account for heterogeneity in the prevalence of H. pylori infection as a function of birth year. The prevalence of H. pylori infection confirmed a clear birth cohort pattern: the predicted prevalence (%, 95% CI) was 60.9 (56.3–65.4), 65.9 (63.9–67.9), 67.4 (66.0–68.7), 64.1 (63.1–65.1), 59.1 (58.2–60.0), 49.1 (49.0–49.2), 34.9 (34.0–35.8), 24.6 (23.5–25.8), 15.6 (14.0–17.3), and 6.6 (4.8–8.9) among those who were born in the year 1910, 1920, 1930, 1940, 1950, 1960, 1970, 1980, 1990, and 2000, respectively. The present study demonstrated a clear birth-cohort pattern of H. pylori infection in the Japanese population. The decreased prevalence of H. pylori infection in successive generations should be weighed in future gastric cancer control programs.

Cancer in Japan: Prevalence, prevention and the role of heterocyclic amines in human carcinogenesis

In this article, three topics are being studied in order to understand the present state of cancer in Japan. First, the statistics on cancer mortality indicates that the mortality from cancer in young individuals has been decreasing during the last 50 years, although the total mortality from cancer has been steadily and steeply increasing. Second, epidemiological analyses of cancer causes in Japan indicated that 50 % of cancer cases are preventable, and that prevention of infection and refraining from tobacco smoking will reduce cancer mortality by about 40 %. Third, mutagenic/carcinogenic heterocyclic amines present in cooked meat/fish have been suggested to be carcinogenic in humans in many epidemiological studies carried out in Japan and other countries.

Rate ofHelicobacter pyloriInfection in Children and Clonality of Taiwan Strains

The infection rate of Helicobacter pylori in children from < 1 to 17 years old was investigated. Three techniques, namely culture, CLO test, and PCR, were employed to check the presence or absence of the organism in the antrum of the stomach. Several PCR positives without viable cultures were observed in babies of less than one year old. On the other hand, only two viable cultures were obtained from toddlers of less than two years old. The percentage of positive cultures steadily increased from 8% (3 of 42 cases) in the 0-4 years old age group to 32% (32 of 99 cases) in the 13-17 years old age group. A steady increase also was observed in the result of the CLO test. In PCR, the percentage of positives was greatly higher than that seen with the culture or CLO test. The rate of PCR positives also showed an increase with age but of a much slower rate. The overall infection rate in 295 children was 22% (64 of 295 cases) positive with culture and 76% (225 of 295 cases) with PCR, in contrast to 85% (40 of 49 cases) and 92% (43 of 47 cases), respectively, in adults. The urease activity of the H. pylori derived from children was much lower than that derived from adults (P < 0.001). Taken together, these results suggest that a child might be repeatedly infected and some infecting strains eventually might obtain a steady infection, perhaps by a strain of higher virulence such as higher urease activity. The base variations in the nucleotide sequences did not correlate to the varied urease activities or to the age of the child. The sequences, however, indicated that there were two types of strains. The strains in Taiwan appeared to be derived from the French type strain and not the English type strain. The amino acid sequences of the ureA and the phylogenetic relationship of the 29 strains indicated that the strains in Taiwan are rapidly evolving into a unique clone.

Attributable causes of cancer in Japan in 2005--systematic assessment to estimate current burden of cancer attributable to known preventable risk factors in Japan

BACKGROUND

To contribute to evidence-based policy decision making for national cancer control, we conducted a systematic assessment to estimate the current burden of cancer attributable to known preventable risk factors in Japan in 2005.

METHODS

We first estimated the population attributable fractions (PAFs) of each cancer attributable to known risk factors from relative risks derived primarily from Japanese pooled analyses and large-scale cohort studies and the prevalence of exposure in the period around 1990. Using nationwide vital statistics records and incidence estimates, we then estimated the attributable cancer incidence and mortality in 2005.

RESULTS

In 2005, ≈ 55% of cancer among men was attributable to preventable risk factors in Japan. The corresponding figure was lower among women, but preventable risk factors still accounted for nearly 30% of cancer. In men, tobacco smoking had the highest PAF (30% for incidence and 35% for mortality, respectively) followed by infectious agents (23% and 23%). In women, in contrast, infectious agents had the highest PAF (18% and 19% for incidence and mortality, respectively) followed by tobacco smoking (6% and 8%).

CONCLUSIONS

In Japan, tobacco smoking and infections are major causes of cancer. Further control of these factors will contribute to substantial reductions in cancer incidence and mortality in Japan.

Single nucleotide polymorphism of interleukin-1beta associated with Helicobacter pylori infection in immune thrombocytopenic purpura

To examine the role of genetic factors in development of immune thrombocytopenic purpura (ITP) in association with Helicobacter pylori infection, gene polymorphisms within the loci for human leukocyte antigen class II, interleukin (IL)-1beta (-511), tumor necrosis factor-beta (+252), immunoglobulin (Ig)G1 heavy chain (+643), and Igkappa light chain (+573) were determined in 164 adults with ITP and 75 healthy controls. Of these gene polymorphisms, the IL-1beta (-511) T allele was less frequently detected in H. pylori-infected than in H. pylori-uninfected (58% vs 81%, P = 0.01, odds ratio = 0.31) ITP patients diagnosed before age 50. These findings suggest that a single nucleotide polymorphism within the IL-1beta (-511) may affect susceptibility to early-onset ITP associated with H. pylori infection.

The transmission of Helicobacter pylori: the effects of analysis method and study population on inference

Although much is known about the virulence of Helicobacter pylori, the transmission pathways for this bacterium are still unresolved. Transmission has been addressed through: (1) prevalence within families; (2) detection in fecal/oral environments; (3) detection in the abiotic/biotic environment; and (4) direct inference from strain similarity. Here, we review the molecular and biochemical methods used and discuss the relative merits of each. Furthermore, as there are differences between developing and developed nations, we discuss the results obtained from transmission studies in light of the study population. We conclude that H. pylori is probably transmitted person-to-person, facilitated by fecal-oral transmission during episodes of diarrhea or gastro-oral contact during periods of vomiting. The persistence of H. pylori in abiotic and biotic environments remains unproven but possible reactivation from viable, non-culturable coccoid forms should be further investigated. Finally, we speculate on the effect of host-pathogen interactions in confounding the inference of transmission.

Is Helicobacter pylori infection a risk factor for acute coronary syndromes?

OBJECTIVES

To elucidate risk factors for acute coronary syndromes (ACS), the present study examined whether Helicobacter pylori infection is a risk factor for patients with ACS.

METHODS

We studied 33 male patients with acute coronary syndromes (ACS). All patients were incidence cases of ACS that they did not have a past history of IHD and were at the first onset of ACS. A control group was consisted of 66 males. Controls were at random selected from outpatients. All controls had normal resting electrocardiogram and had no history of IHD. H. pylori seropositivity was determined by an IgG-specific enzyme linked immunosorbent assay (ELISA). We serologically confirmed the presence of antibodies specific to the antigen CagA of H. pylori, using CagA ELISA.

RESULTS

Seropositive rate of IgG antibodies in patients with ACS was 87.9%. A rate of in controls was 66.7%. After adjustment for age, a statistically significant association was found in H. pylori seropositivity between ACS and controls (OR, 3.74; 95% CI, 1.15-12.13). This relation was also significant after adjusted for potential confounding factors (OR, 4.09; 95% CI, 1.10-15.17). Anti-CagA positive H. pylori were significantly recognized in ACS (adjusted OR, 3.58; 95% CI, 1.08-11.82). However, this significant association was disappeared after adjusted for potential confounding factors (P=0.054).

CONCLUSIONS

We confirmed a significant link between H. pylori infection and ACS. H. pylori infection is likely to be a risk factor for ACS.

Prevalence of Helicobacter pylori infection, endoscopic gastric findings and dyspeptic symptoms among a young Japanese population born in the 1970s

BACKGROUND

With the prevalence of Helicobacter pylori (H. pylori) infection rapidly decreasing in Japan, endoscopic findings and dyspeptic symptoms need to be re-evaluated.

METHODS

In a health check-up program, endoscopy was performed on 530 young Japanese subjects (371 men and 159 women) born in the 1970s. Helicobacter pylori infection was evaluated using serology and a rapid urease test. Endoscopic gastritis was classified according to the Sydney classification system, in addition to nodular gastritis. Dyspeptic symptoms were also recorded before endoscopy.

RESULTS

Of the 530 subjects, 87 (16.4%) were H. pylori positive. Of the 443 H. pylori-negative subjects, 349 (78.8%) were considered to have endoscopically normal gastric mucosa. However, of the 87 H. pylori-positive subjects, only 19 (21.8%) tested normal (P < 0.001). The prevalence of several types of gastritis was significantly higher in H. pylori-positive subjects compared with H. pylori-negative subjects: atrophic gastritis (37.9% vs 1.1%, P < 0.001), flat erosive gastritis (29.9% vs 7.2%, P < 0.001), rugal hyperplastic gastritis (12.6% vs 0.0%, P < 0.001), and nodular gastritis (13.8% vs 0.0%, P < 0.001). Other types of gastritis were not related to H. pylori status. The prevalence of subjects with dyspeptic symptoms was significantly higher in H. pylori-positive subjects compared with H. pylori-negative ones (28.7% vs 6.5%, P < 0.001).

CONCLUSION

It is suggested that in consideration of its recent low prevalence and the slow increase in its infection, the prevalence of H. pylori-related gastritis will gradually decrease in Japan. Further studies will be required to ascertain if there is a need for H. pylori eradication in this young population.

Incidence and mortality from stomach cancer in Japan, Slovenia and the USA

The mortality and incidence from stomach cancer were compared in Japan (a country with a high incidence where there was full application of mass screening during this period) and 2 countries with no screening policy: the USA (with a very low incidence) and Slovenia (with an intermediate rate). The registered cases of stomach cancer were from the Osaka Cancer Registry, the Slovenian National Cancer Registry and the Surveillance, Epidemiology, and End Results (SEER) registries in the USA. In the period 1975-95, the age-adjusted incidence rate (/100,000) of stomach cancer declined in the 3 countries, as follows: Japan, from 76.0 to 53.0 in men and 38.4 to 21.3 in women; Slovenia, from 40.2 to 24.1 in men and 16.6 to 10.8 in women; and the USA, from 9.5 to 6.9 in men and 4.3 to 2.9 in women. During the same period, the age-adjusted mortality rate declined, as follows: Japan, from 60.2 to 34.2 in men and 30.5 to 14.1 in women; Slovenia, from 37.7 to 21.2 in men and 13.8 to 9.0 in women; the USA, from 5.6 to 4.7 in men and 2.5 to 2.3 in women. In the period studied, specific trends on incidence and mortality with a cohort effect occurred only in Japan: analysis by the age period-cohort model confirmed that the decline has occurred since the generations born in 1910. The trend therefore corresponds to unplanned prevention through changes in environmental factors occurring since the early 20th century. The study of stage-specific incidence rates confirmed the declining trend for regional cancer, whereas there was an increase in the incidence of localized cancer, associated with a period effect in 1975-95. This is attributed to the policy of early detection of stomach cancer, with the inclusion of intramucosal lesions of favorable prognosis and explains why mortality decreased faster than incidence during the period.

Trends in reported adenocarcinomas of the oesophagus and gastric cardia in Japan

Adenocarcinomas involving the oesophagus and gastric cardia are becoming more common in Western countries, but data from Japan are limited. We sought to determine whether the frequency of these cancers in Japan has increased in recent decades. Review of national cancer mortality data, national registries of oesophageal and gastric cancer cases, and records from two large cancer centres for various time periods between 1950 and 1998 did not show increased reporting of oesophageal adenocarcinomas. In contrast, both national and cancer centre data indicate an absolute increase in the number of gastric cancers involving the C-area (proximal third of the stomach). From a national registry of resected primary gastric cancer cases, those arising in the C-area as a proportion of all tumours rose by 41.8% between 1963 (12.2% of all registered cases) and 1990 (17.3%). Analysis of true cardia (<2 cm distal to oesophagus-cardia junction) early cancers from the two cancer centres showed significant increases in both absolute number and in proportion to other gastric cancers over a 36-year period. These data suggest that the frequency of cardia cancers is increasing in Japan. Lack of a parallel increase in oesophageal adenocarcinomas could be due to misclassification artefacts and/or coding preferences for gastro-oesophageal junction tumours.

Demography of longevity: past, present, and future trends

Life expectancy at birth has roughly tripled over the course of human history. Early gains were due to a general improvement in living standards and organized efforts to control the spread of infectious disease. Reductions in infant and child mortality in the late 19th and early 20th century led to a rapid increase in life expectancy at birth. Since 1970, the main factor driving continued gains in life expectancy in industrialized countries is a reduction in death rates among the elderly. In particular, death rates due to cardiovascular disease and cancer have declined in recent decades thanks to a variety of factors, including successful medical intervention. Based on available demographic evidence, the human life span shows no sign of approaching a fixed limit imposed by biology or other factors. Rather, both the average and the maximum human life span have increased steadily over time for more than a century. The complexity and historical stability of these changes suggest that the most reliable method of predicting the future is merely to extrapolate past trends. Such methods suggest that life expectancy at birth in industrialized countries will be about 85-87years at the middle of the 21st century.

A comprehensive review of the natural history of Helicobacter pylori infection in children

Across populations of children, Helicobacter pylori prevalence ranges from under 10% to over 80%. Low prevalence occurs in the U.S., Canada, and northern and western Europe; high prevalence occurs in India, Africa, Latin America, and eastern Europe. Risk factors include socioeconomic status, household crowding, ethnicity, migration from high prevalence regions, and infection status of family members. H. pylori infection is not associated with specific symptoms in children; however, it is consistently associated with antral gastritis, although its clinical significance is unclear. Duodenal ulcers associated with H. pylori are seldom seen in children under 10 years of age. H. pylori-infected children demonstrate a chronic, macrophagic, and monocytic inflammatory cell infiltrate and a lack of neutrophils, as compared with the response observed in adults. The effect of H. pylori infection on acid secretion in children remains poorly defined. The events that occur during H. pylori colonization in children should be studied more thoroughly and should include urease activity, motility, chemotaxis, adherence, and downregulation of the host response. The importance of virulence determinants described as relevant for disease during H. pylori infection has not been extensively studied in children. Highly sensitive and specific methods for the detection of H. pylori in children are needed, especially in younger pediatric populations in which colonization is in its early phases. Criteria for the use of eradication treatment in H. pylori-infected children need to be established. Multicenter pediatric studies should focus on the identification of risk factors, which can be used as prognostic indicators for the development of gastroduodenal disease later in life.

Transmission of Helicobacter pylori

Helicobacter pylori is found predominantly in human gastric mucosa. Transfer of the bacterium remains an open topic, but it is likely that infection is usually acquired at a young age, particularly where lower socio-economic conditions prevail. Transmission via an external source such as water supply is a possibility but, in general, infection is probably passed from person to person. Arguments for and against faecal-oral, oral-oral and gastric-oral transmission have been presented, but the dominance of one of these routes is still to be determined.

Comparison of biopsy and serological methods of diagnosis of Helicobacter pylori infection and the potential role of antibiotics

OBJECTIVE

Endoscopic biopsy and serological methods were compared for their ability to detect Helicobacter pylori infection in patients undergoing upper gastrointestinal endoscopy at a state university hospital.

METHODS

Subjects were characterized on the basis of gastrointestinal symptoms, endoscopic findings, socioeconomic and demographic features, and the use of certain medications, tobacco, and alcohol. Current infection was detected in gastric antral specimens by rapid urease testing, histopathology, and bacterial culture. Serum levels of IgG to H. pylori were measured by ELISA.

RESULTS

Of 240 subjects, 115 (47.9%) were currently infected as determined by rapid urease testing, histopathology, and/or culture results, whereas 63.3% had elevated anti-H. pylori IgG levels (p < 0.001). This difference in the prevalence of current infection and seropositivity was preserved when the study population was analyzed according to age, race, gender, and other characteristics. Prior use of antibiotics was associated with a significant reduction in the frequency of H. pylori infection.

CONCLUSIONS

Serological evidence of H. pylori infection was consistently greater than the prevalence of infection documented by biopsy methods in this study, suggesting suppression or recent clearance of infection. Further studies are needed to examine the factors that may affect the detection of H. pylori infection.

A serologic survey of Helicobacter pylori infection in 3281 Italian patients endoscoped for upper gastrointestinal symptoms. The Italian Helicobacter Pylori Study Group

AIM

To assess the seroprevalence of Helicobacter pylori infection in a large series of patients with upper gastrointestinal symptoms referred for their first upper gastrointestinal endoscopy, and to evaluate any association with disease.

METHODS

A large survey of 3281 dyspeptic patients undergoing their first endoscopic examination was undertaken, involving 93 centres in Italy. A blood sample was taken from each participant, for measuring IgG antibodies against H. pylori using a commercially available kit, and two biopsies of the antral gastric mucosa were obtained for evaluating a Giemsa-stained specimen.

RESULTS

Endoscopic macroscopic diagnoses included normal mucosa (25.3%), gustroduodenitis (51.6%), gastric and duodenal ulcers (3.7 and 14.9%, respectively) and other conditions, including gastric cancer (0.8%). Overall, the seroprevalence result was 71.3% with a strong positive association with increasing age and male sex and a negative one with educational level. According to endoscopic diagnoses, the association with H. pylori seropositivity was highest for duodenal and gastric ulcer (multivariate odds ratio: 6.1 and 2.2) and lowest for carcinoma. The comparison between the results of serology and the single Giemsa-stained specimen showed good reliability of H. pylori IgG, particularly in a subgroup (n = 2056) for which the interpretation was performed by a single dedicated pathologist: sensitivity and specificity were 92 and 78%, respectively.

CONCLUSION

Commercial IgG serology is a reliable tool for the assessment of H. pylori infection in large-scale multicentre surveys. A very high seroprevalence among dyspeptic patients was confirmed, particularly in the presence of peptic disease. Factors associated with the infection were very similar to those usually reported in the general population, but male patients showed a significantly higher prevalence.

Evaluation of the aetiological role of dietary salt exposure in gastric and other cancers in humans

The findings in laboratory and epidemiological studies relevant to the assessment of salt for carcinogenic potential are reviewed. Associations between the high consumption of certain highly salted foodstuffs, particularly in some oriental countries, and increased risk of cancer of the stomach do not incriminate salt per se. Some highly spiced foods contain potent genotoxic carcinogens, irrespective of whether they also contain salt. There is evidence in laboratory animals that high concentrations of salt may increase the incidence of gastric cancer caused by such carcinogens. This may well be attributable to a marked and sustained regenerative response in the gastric mucosa of laboratory animals chronically exposed to the cytotoxicity of hyperosmolar concentrations of salt, such a mitogenic response favouring the progression towards neoplasia. However, there is no laboratory evidence whatsoever to indicate that salt per se is a carcinogen for any site in the body; neither is there any reliable epidemiological evidence to indicate that dietary salt affects the incidence of gastric or other cancers. A particular problem in the interpretation of epidemiological studies is that the consumption of diets containing highly salted, spicy foods is often associated with low intakes of fruit and green vegetables, which contain cancer-protective antioxidants. In Western countries the incidence of cancer of the stomach has been falling for some 50 years. The consensus view is that this fall is attributable to improved food hygiene and increasingly available facilities for refrigeration. There are no grounds for supposing that the fall is attributable to a decreasing intake of salt. A high dietary salt intake does not necessarily entail exposure to salt in concentrations high enough to damage the gastric mucosa. The typical Western diet would not be expected to provide such high salt concentrations. It is concluded that there are no grounds for believing that a reduction in the average daily salt intake in the Western diet would have any effect on the risk of developing any form of cancer.

Modelling cost-effectiveness of Helicobacter pylori screening to prevent gastric cancer: a mandate for clinical trials

BACKGROUND

It is unknown whether eradication of Helicobacter pylori infection prevents development of gastric adenocarcinoma. To determine whether screening and treatment trials are warranted, we conducted a cost-effectiveness analysis to estimate the costs and benefits associated with screening for H pylori at age 50 and treating those individuals infected with antibiotics.

METHODS

We compared two interventions: (1) screen for H pylori and treat those with a positive test, and (2) do not screen and do not treat. Estimates of risks and costs were obtained by review of published reports. Since the efficacy of H pylori therapy in cancer prevention is unknown, we did sensitivity analyses, varying this estimate widely. In our base-case analysis, we assumed that H pylori treatment prevented 30% of attributable gastric cancers.

FINDINGS

In the base-case analysis, 11,646,000 persons in the US would be screened and 4,658,400 treated, at a cost of $996 million. Cost-effectiveness was $25,000 per year of life saved. Cost-effectiveness was sensitive to the efficacy of the cancer prevention strategy. At low efficacy rates (< 10%), the screening programme was more expensive (> $75,000 per year of life saved). In a high-risk group such as Japanese-Americans, however, screening and treatment required less than $50,000 per year of life saved, even at 5% treatment efficacy.

INTERPRETATION

Screening and treatment for H pylori infection is potentially cost-effective in the prevention of gastric cancer, particularly in high-risk populations. Cancer prevention trials are strongly recommended.