Lifetime incidence risk for gastric cancer in the Helicobacter pylori-infected and uninfected population in Japan: A Monte Carlo simulation study.

Helicobacter pylori (H. pylori) infection is considered the leading cause of gastric cancer. Gastric cancer is currently a common cancer with high incidence and mortality rates, but it is expected that the incidence rate will gradually decrease as the H. pylori infection prevalence decreases in the future. When evaluating the effectiveness of gastric cancer prevention strategies, it is essential to note the differences in long-term cumulative risks between H. pylori-infected and uninfected populations, but this has not yet been precisely evaluated. In our study, we aimed to estimate the cumulative incidence risks of developing gastric cancer from birth to 85 years among H. pylori-infected and uninfected populations by using population-based cancer registry data and birth year-specific H. pylori infection prevalence rates. Death from gastric cancer and other causes of death were considered in the estimations of the adjusted cumulative incidence risks stratified by sex and H. pylori infection status. After performing 5000 Monte Carlo simulations with repeated random sampling using observed cancer incidence in selected three prefectures (Fukui, Nagasaki, Yamagata) of prefectural population-based cancer registry in Japan, the mean adjusted cumulative incidence risk for gastric cancer in the H. pylori-infected population was 17.0% for males and 7.7% for females and 1.0% for males and 0.5% for females in the uninfected population. These results calculated with Japanese cancer registry data may be useful in considering and evaluating future prevention strategies for gastric cancer in Japan.

Associations between cigarette smoking and biliary tract cancer by anatomic subsite and sex: a prospective cohort study in Japan.

PURPOSE: Biliary tract cancer (BTC) has not been considered a tobacco-related cancer, largely because of inconclusive results from epidemiological studies. We herein evaluate the association between cigarette smoking and risk of death from BTC by anatomic subsite and sex using data from a large, prospective cohort study in Japan. METHODS: The present study included 97,030 Japanese individuals who were enrolled in 1988-1990 and followed until 31 December 2009. Cox proportional hazards regression models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for the association of BTC with cigarette smoking, including smoking status, number of cigarettes smoked per day, and pack-years of smoking. RESULTS: During a mean follow-up of 16.2 years, we documented 484 deaths (187 from gallbladder cancers and 297 from cancers of other and unspecified biliary tract parts). After adjustment for sex, age, body mass index, alcohol consumption, and history of gallstones, current smokers had a higher risk of death due to BTC (RR = 1.35, 95% CI = 1.01-1.79) than never smokers. In the analyses by anatomic subsite, current smoking was associated with an increased risk of death from gallbladder cancer (RR = 1.89 95% CI = 1.19-3.02), whereas no evidence of an association was noted for cancers of other and unspecified biliary tract parts (RR = 1.10, 95% CI = 0.77-1.58). Moreover, mortality risk increased with an increasing number of cigarettes smoked per day and pack-years of smoking, particularly for gallbladder cancer in men. CONCLUSION: Cigarette smoking is associated with an increased risk of death from BTC, particularly gallbladder cancer, in Japanese men.

Prevalence estimates of Helicobacter species infection in pancreatic and biliary tract cancers.

BACKGROUND: Helicobacter pylori infection is a well-established risk factor for gastric cancer and has been linked to other gastrointestinal diseases, including pancreatic and biliary tract cancers; however, the relevance of enterohepatic non-H. pylori helicobacters to the pathophysiology of these diseases remains unclear. MATERIALS AND METHODS: We estimated the prevalence of two enterohepatic non-H. pylori helicobacters (Helicobacter hepaticus and Helicobacter bilis) in the framework of a hospital-based case-control study involving 121 patients with biliary tract cancer, pancreatic cancer, or other gastrointestinal diseases. Bile and blood samples were collected from the patients undergoing endoscopic retrograde cholangiopancreatography. The presence of H. bilis, H. hepaticus, and other Helicobacter spp. was examined using bacterial culture, PCR-based detection, and serological tests. RESULTS: Culture of Helicobacter spp. from biliary brush samples was unsuccessful. Approximately 13.0% (15/115) of the bile samples collected from patients with a variety of gastrointestinal cancers, including pancreatic and biliary tract cancers, tested positive for one of the enterohepatic non-H. pylori helicobacter species as determined by PCR. Specifically, H. bilis and H. hepaticus DNA were detected in 11 and 4 bile samples, respectively. Approximately 20%-40% of the patients tested positive for serum non-H. pylori helicobacter IgG antibodies. The seroprevalence of H. bilis and H. hepaticus in the patients without evidence of H. pylori infection appeared to be higher in the pancreatic cancer group than in the control group. CONCLUSION: Our findings suggest a role for Helicobacter spp., especially H. bilis and H. hepaticus, in the etiology of pancreatic and biliary tract cancers.

Higher proportions of a healthy gastric mucosa in healthy Japanese adults with later birth year: analysis of 41 957 participants.

BACKGROUND: In Japan, most gastric cancers are associated with gastric mucosal atrophy caused by chronic infection with Helicobacter pylori (H. pylori). Recognizing the condition of the gastric mucosa and determining the infection status of H. pylori are important for predicting the individual risk of gastric cancer. This study aimed to determine the proportion of Japanese adults with a healthy gastric mucosa (without H. pylori infection) among 12 birth-year groups encompassing 1935-1990 by morphological images. METHODS: The gastric mucosa was classified as healthy or having gastritis based on routine double-contrast upper gastrointestinal barium X-ray radiography. The participants included 41 957 healthy Japanese adults. Serum or urine H. pylori antibody levels were also assessed. RESULTS: In total, 25 424 participants had healthy mucosa without a history of H. pylori eradication. The proportions of participants with a healthy mucosa by birth year were 19.8% (57/288), 27.1% (306/1128), 32.4% (569/1756), 37.6% (1808/4811), 49.2% (3207/6522), 60.1% (3966/6550), 71.2% (5224/7342), 77.2% (5114/6624), 80.6% (3342/4149), 85.0% (1404/1652), 85.3% (302/354) and 94.7% (125/132) in 1935, 1940, 1945, 1950, 1955, 1960, 1965, 1970, 1975, 1980, 1985 and after 1990, respectively (P for trend <0.01). All the participants with a healthy mucosa showed negative results in the H. pylori antibody tests. CONCLUSIONS: The proportion of participants with normal gastric mucosa linearly increased with the birth years. The prevalence of morphologically healthy gastric mucosa could have consistently increased with decreasing prevalence of H. pylori infection.

Treatment patterns in pancreatic cancer patients based on a hospital claims database in Japan.

BACKGROUND: Pancreatic cancer treatment is evolving, but few studies have examined a nationwide trend in the treatment patterns. The purpose of this study was to clarify real-world treatment patterns for pancreatic cancer in Japan. METHODS: This retrospective study examined the treatment patterns among 68 479 patients, who had pancreatic cancer diagnosis in Medical Data Vision claims database from 2010 to 2018. We extracted relevant data on treatment options, including chemotherapy, surgery and their combination. For patients who had undergone chemotherapy, we sought to analyse the use of different chemotherapy regimens. In addition, we examined the trend in treatment patterns by age group (<59, 60-69, 70-79, ≥80). RESULTS: The trend in treatment options of pancreatic cancer remained stable from 2010 to 2018, with chemotherapy being the most common therapeutic option and surgery performed in approximately half that of chemotherapy. On the other hand, the use of chemotherapy regimen had changed during the same period. Although gemcitabine was the most commonly administrated single-agent regimen in 2010, gemcitabine + nab-paclitaxel was the most frequently used therapeutic agent in 2018. In the older age groups (age ≥80), the majority of patients was untreated (supposedly received supportive care), and the use of conventional regimens such as gemcitabine or S-1 was common among those undergoing chemotherapy. CONCLUSIONS: Although chemotherapy has been the main treatment option for pancreatic cancer, the regimens of choice have increased significantly during the last decade. With accumulating evidence on combination chemotherapy, treatment options may further evolve in the future.

Effects of Helicobacter pylori eradication on gastric cancer incidence in the Japanese population: a systematic evidence review.

BACKGROUND: In Japan, there are ongoing efforts to shift the gastric cancer prevention and control policy priorities from barium-based screening to Helicobacter pylori (H. pylori)-oriented primary prevention. A comprehensive summary of the evidence regarding the effects of H. pylori eradication on the risk of gastric cancer could inform policy decisions. METHODS: We conducted a systematic review and meta-analysis of published studies evaluating the effectiveness of H. pylori eradication for the prevention of gastric cancer in otherwise healthy individuals (primary prevention) and early gastric cancer patients (tertiary prevention). RESULTS: In total, 19 studies were included. Three moderate-quality observational cohort studies showed that H. pylori eradication may be associated with a decreased risk of gastric cancer in healthy asymptomatic Japanese people. There is moderate certainty regarding the effectiveness of H. pylori eradication in patients with gastrointestinal diseases, such as peptic ulcers. A meta-analysis of 10 observational studies with otherwise healthy individuals (mainly peptic ulcer patients) yielded an overall odds ratio of 0.34 (95% CI: 0.25-0.46). Regarding tertiary prevention, the overall odds ratio for developing metachronous gastric cancer was 0.42 (95% CI: 0.35-0.51) in the eradication group in a meta-analysis of nine studies involving early gastric cancer patients who underwent endoscopic resection. CONCLUSION: H. pylori eradication is effective in preventing gastric cancer in the Japanese population, regardless of symptoms. Well-designed, large cohort studies are warranted to determine the long-term efficacy and safety of H. pylori eradication in the context of reducing the gastric cancer burden through population-based screening and treatment.

A Retrospective Database Study of Gastrointestinal Events and Medical Costs Associated with Nonsteroidal Anti-Inflammatory Drugs in Japanese Patients of Working Age with Osteoarthritis and Chronic Low Back Pain.

CONTEXT: The real-world burden of gastrointestinal (GI) events associated with the use of nonsteroidal anti-inflammatory drugs (NSAIDs) in Japanese patients with osteoarthritis (OA) and/or chronic low back pain (CLBP) remains unreported. OBJECTIVE: To assess the incidence and economic burden of NSAID-induced GI events by using data from large-scale real-world databases. METHODS: We used the Japanese Medical Data Center database to retrospectively evaluate anonymized claims data of medical insurance beneficiaries employed by middle- to large-size Japanese companies who were prescribed NSAIDs for OA and/or CLBP between 2009 and 2018. RESULTS: Overall, 180,371 patients were included in the analysis, of whom 32.9% had OA, 53.8% had CLBP, and 13.4% had both OA and CLBP. NSAIDs were administered as first-line analgesics to 161,152 (89.3%) of the patients in the sample, in oral form to 90.3% and as topical patches to 80.4%. A total of 65.1% used combined oral/topical patches. Of the 21.0% of patients consistently using NSAIDs (percentage of days supplied ≥70%), 54.5% received patches. A total of 51.5% patients used NSAIDs for >1 to ≤6 months. The incidence of GI events was 9.97 per 10,000 person-years (95% confidence interval: 8.92-11.03). The risk of developing GI events was high in elderly patients and patients with comorbidities and remained similar for patients receiving oral vs. topical NSAIDs. Longer treatment duration and consistent NSAID use increased the risk of GI events. The cost (median [interquartile range]) of medications (n = 327) was US$ 80.70 ($14.10, $201.40), that of hospitalization (n = 33) was US$ 2,035.50 ($1,517.80, $2,431.90), and that of endoscopic surgery (n = 52) was US$ 418.20 ($418.20, $418.20). CONCLUSION: NSAID-associated GI toxicity imposes a significant health and economic burden on patients with OA and/or CLBP, irrespective of whether oral or topical NSAIDs are used.

A nationwide questionnaire survey on accidental magnet ingestion in children in Japan.

AIM: The aim is to investigate the actual situation of accidental ingestion of magnets in children in Japan and the clinical features of the resulting gastrointestinal damage. METHODS: We developed a questionnaire and sent it to 496 board-certified training hospitals nationwide. Information was collected on the number of children with accidental magnet intake from 2015 to 2017, witnesses of magnet intake, number and type of magnets, presence or absence of gastrointestinal injury, treatment, etc RESULTS: The number of cases of accidental ingestion of magnets within the study period was 104, with a median age of 2 years. About half of the incidents were unwitnessed. There were 33 cases of accidental ingestion of multiple magnets. Among them, oesophagogastroduodenoscopy was performed in 4 children and surgery in 10, and significantly invasive treatment was required in comparison with single-magnet ingestion. Gastrointestinal injury was observed in 11 cases, 10 of which were caused by multiple-magnet ingestion. All 10 of these patients underwent surgical treatment. There was no mortality. CONCLUSION: The incidence of accidental magnet ingestion in Japan is estimated to be 50-70 per year. Unwitnessed cases are not uncommon. Multiple magnet ingestion often causes gastrointestinal injury. Many cases of gastrointestinal injury are caused by ingestion of magnetic toys.

Gastric cancer deaths by age group in Japan: Outlook on preventive measures for elderly adults.

In February 2013, Japan became the first country in the world to cover Helicobacter pylori eradication for chronic gastritis under its National Health Insurance (NHI) system. Now that eradication therapy is covered by NHI, its usage has increased dramatically, and gastric cancer deaths have begun to decrease. We undertook a detailed epidemiological analysis to investigate effects of expanded NHI coverage for H. pylori eradication therapy on gastric cancer deaths in specific age groups. Numbers of gastric cancer deaths were determined by referencing data from Ministry of Health, Labour and Welfare reports and "Cancer Statistics in Japan - 2018" published by the Foundation for Promotion of Cancer Research. Gastric cancer deaths across all age groups have been clearly decreasing since 2013, but deaths of people aged 80 years and older are still increasing. The number of gastric cancer deaths in people aged in their 80s was 2 times higher than in people aged in their 70s and 4 times higher than in people aged in their 60s. The number of people in their 80s who had an endoscopy was less than half that of people in their 60s and 70s. The eradication therapy has increased dramatically, and gastric cancer deaths are clearly decreasing in Japan. However, this decrease in deaths has not extended to elderly adults aged in their 80s, which suggests that measures to prevent gastric cancer in people aged 80 years and older will be critical to achieving the mission of eliminating gastric cancer in Japan.

Serum Pepsinogen Values in Japanese Junior High School Students With Reference to Helicobacter Pylori Infection.

BACKGROUND: Distributions of serum pepsinogen (PG) values were assessed in Helicobacter pylori-infected and non-infected junior high school students (aged 12-15 years) in Japan. METHODS: All junior high school students (1,225 in total) in Sasayama city, who were basically healthy, were asked to provide urine and serum samples, which were used to measure urine and serum H. pylori antibodies using ELISA kits and PG values. The subjects, whose urine and serum antibodies were both positive, were considered H. pylori infected. RESULTS: Of the 187 subjects who provided urine and blood samples, 8 were infected, 4 had discrepant results, 4 had negative serum antibody titers no less than 3.0 U/ml, and 171 were non-infected. In the H. pylori non-infected subjects, the median PG I and PG II values and PG I to PG II ratio (PG I/II) were 40.8 ng/mL, 9.5 ng/mL, and 4.4, respectively, whereas in the infected subjects, these values were 55.4 ng/mL, 17.0 ng/mL, and 3.3, respectively (each P < 0.01). In the non-infected subjects, PG I and PG II were significantly higher in males than in females (P < 0.01). CONCLUSIONS: The PG I and PG II values were higher, and the PG I/II was lower in H. pylori infected students than in non-infected students. In H. pylori non-infected students, males showed higher PG I and PG II values than females. The distributions of PG values in junior high school students differed from those in adults.

DNA Adductome Analysis Identifies N-Nitrosopiperidine Involved in the Etiology of Esophageal Cancer in Cixian, China.

Esophageal cancer is prevalent in Cixian, China, but the etiology of this disease remains largely unknown. Therefore, we explored this by conducting a DNA adductome analysis. Both tumorous and nontumorous tissues were collected from patients who underwent surgical procedures at Cixian Cancer Hospital and the Fourth Hospital of Hebei Medical University, which is in a low-incidence area. N2-(3,4,5,6-Tetrahydro-2H-pyran-2-yl)deoxyguanosine (THP-dG) was the major adduct detected in samples from esophageal cancer patients in Cixian. The precursor of THP-dG, N-nitrosopiperidine (NPIP), exhibited a strong mutagenic activity under metabolic activation in the Ames test and a significant dose-dependent increase in mutation frequency during an in vivo mutagenicity test with guanine phosphoribosyltransferase (gpt) delta rats. The NPIP-induced mutation was dominated by A:T to C:G transversions, followed by G:C to A:T and A:T to G:C transitions, in the liver and esophagus of animal samples. A similar mutational pattern was observed in the mutational signature of esophageal cancer patients that demonstrated weak correlation with THP-dG levels. These findings suggested that NPIP exposure is partly involved in the development of esophageal cancer in Cixian residents.

Metronidazole for Helicobacter pylori eradication therapy among children and adolescents in Japan: Overcoming controversies and concerns.

BACKGROUND: Metronidazole is an antiprotozoal drug used to treat a broad spectrum of infectious diseases, including Helicobacter pylori (H pylori) infections. In Japan, metronidazole is approved for the eradication therapy of H pylori as a second-line regimen among adults, but it has not yet been approved for use among children and adolescents. MATERIALS AND METHODS: To perform this narrative review, we searched the relevant literature on important events in the history of the use of metronidazole, its mechanisms of action, its efficacy, and the adverse effects reported in clinical trials or cohort studies in Japan. RESULTS: At present, metronidazole resistance has not been a serious issue in Japan in large part due to its restricted use. Emerging evidence from randomized controlled trials demonstrates higher eradication rates for metronidazole than for clarithromycin, supporting its use in both first-line and second-line eradication therapies. Among the reported adverse effects, there has been lingering concern over the potential carcinogenicity of metronidazole in humans. However, the possibility of an increased cancer risk is not limited to metronidazole; the long-term use of antibiotics has been linked to increased risk for some site-specific cancers. However, recent prospective studies have suggested that short-term exposure to antibiotics is not associated with an increased cancer risk. CONCLUSION: Sensible use of metronidazole backed by research evidence could maximize the benefits associated with H pylori eradication in Japan.

Guidelines for the management of Helicobacter pylori infection in Japan: 2016 Revised Edition.

BACKGROUND: Since "Helicobacter pylori (H. pylori) infection" was set as the indication in the Japanese Society for Helicobacter Research (JSHR) Guidelines 2009, eradication treatment for H. pylori gastritis is covered under insurance since 2013 in Japan, and the number of H. pylori eradication has rapidly increased. Under such circumstances, JSHR has made the third revision to the "Guidelines for diagnosis and treatment of H. pylori infection" for the first time in 7 years. METHODS: The Guideline Committee held 10 meetings. Articles published between the establishment of the 2009 Guidelines and March 2016 were reviewed and classified according to the evidence level; the statements were revised on the basis of this review. After inviting public comments, the revised statements were finalized using the Delphi method. RESULTS: There was no change in the basic policy that H. pylori infectious disease is an indication for eradication. Other diseases presumed to be associated with H. pylori infection were added as indications. Serum pepsinogen level, endoscopic examination, and X-ray examination were added to the diagnostic methods. The effects of 1-week triple therapy consisting of potassium-competitive acid blocker (P-CAB), amoxicillin, and clarithromycin have improved, and high eradication rates can also be expected with proton pump inhibitors (PPI) or P-CAB combined with amoxicillin and metronidazole. If the susceptibility test is not performed, the triple PPI or P-CAB/amoxicillin/metronidazole therapy should be chosen, because the PPI/amoxicillin/metronidazole combination demonstrated a significantly higher eradication rate than PPI/amoxicillin/clarithromycin. In the proposal for gastric cancer prevention, we divided gastric cancer prevention measures by age from adolescent to elderly, who are at an increased gastric cancer risk, and presented measures for gastric cancer prevention primarily based on H. pylori eradication. CONCLUSION: We expect the revised guidelines to facilitate appropriate interventions for patients with H. pylori infection and accomplish its eradication and prevention of gastric cancer.

Optimal Criteria and Diagnostic Ability of Serum Pepsinogen Values for Helicobacter pylori Infection.

BACKGROUND: Practical criteria for the use of serum pepsinogen (PG) values in diagnosing Helicobacter pylori infection have not yet been determined. METHODS: The results of gastric endoscopies, H. pylori infection tests, and PG values were retrospectively reviewed. Subjects were assigned to groups, including never-infected (with neither infection nor gastric mucosal atrophy), infected (with atrophy or findings indicating infection in endoscopy and positive infection tests except for antibody tests), and ex-infected (with gastric mucosal atrophy and negative infection tests, except for antibody tests). The optimal criteria with combined use of the PG II concentrations and the PG I/PG II ratio were investigated separately for PG measurements obtained with the chemiluminescent magnetic particle immunoassay (CLIA) and latex agglutination (LA) methods, such that the specificity was greater than 70% and the sensitivity was no less than 95% among the never-infected and infected subjects. Similar analyses were performed by combining the data from ex-infected and infected subjects. RESULTS: For the CLIA (LA) method, the optimal criterion among 349 (397) never-infected and 748 (863) infected subjects was a PG II value of at least 10 (12) ng/mL or a PG I/PG II ratio no more than 5.0 (4.0), which produced 96.3% (95.1%) sensitivity and 82.8% (72.8%) specificity. When 172 (236) ex-infected subjects were included, the optimal criterion was the same, and the sensitivity was 89.1% (86.9%). CONCLUSIONS: The above criteria may be practical for clinical use, and PG tests using these criteria might prevent unnecessary endoscopic examinations for never-infected subjects.

Rapidly decreasing prevalence of Helicobacter pylori among Japanese children and adolescents.

BACKGROUND: The secular trend in the prevalence of Helicobacter pylori (H. pylori) infection among children and adolescents in Japan has not been well documented. MATERIALS AND METHODS: We reviewed all relevant literature published between 1991 and 2017, focusing on the relationship between the prevalence of H. pylori infection and birth year. Our literature search covered all journal articles, conference proceedings and meeting abstracts that reported the prevalence of H. pylori infection in Japanese subjects under 20 years of age. RESULTS: We examined the prevalence of H. pylori infection according to birth year on the basis of data points, which comprised 20,269 subjects of 81 groups. Three-coefficient logistic regression analysis was performed to examine the trend in H. pylori prevalence. The prevalence was approximately 10% in the individuals born in 1985, but it decreased to 3% in the individuals born in 2011. The plot of H. pylori prevalence against birth year clearly indicated a birth-cohort effect: the earlier the birth year, the higher the prevalence. CONCLUSIONS: Our analysis revealed a rapidly decreasing prevalence of H. pylori infection among Japanese children and adolescents over the past three decades.

Comparison of the detection of Helicobacter pylori infection by commercially available serological testing kits and the 13C-urea breath test.

BACKGROUND: Serum Helicobacter pylori (H. pylori) antibody kits (LZ and LIA) using the latex agglutination immunoassay method are commercially available, but few studies have been performed to determine their diagnostic accuracy or to compare their results with those of enzyme-linked immunosorbent assay (ELISA) kits (EP and EIA). METHODS: Sera were obtained from 213 hospital outpatients with dyspeptic symptoms. The serological results were compared with the result of the 13C-urea breath test (UBT) which seems to be reliable. RESULTS: Of the 213 subjects, 154 were diagnosed as positive for H. pylori infection according to the UBT. The sensitivities and specificities of these tests were 97.4% and 76.3%, 98.1% and 78.0%, 99.4% and 74.6%, and 98.1% and 71.2% for the EP, LZ, EIA and LIA tests, respectively. When the 13 subjects whose seropositive results of the four kits were completely opposite to the negative results of the UBT were excluded, the specificities of evaluated kits were all higher than 90%. The concordance rate between the EP and EIA tests was 98.1% (Spearman's rank correlation coefficient = 0.83) and that between the LZ and LIA tests was 97.1% (correlation coefficient = 0.91). The LZ gave higher antibody titer value than EP (p < 0.0001, Z = 9.82; Wilcoxon signed-rank test), and EIA gave higher value than LIA (p < 0.0001, Z = 6.43; Wilcoxon signed-rank test). CONCLUSIONS: The latex immunoassay method provided the same reliability to ELISA in terms of the diagnostic accuracy for current H. pylori infection, although we should take into account the titer value differences by each test method in practical use.

Helicobacter pylori Infection in Children and Adolescents.

About one-third of all children worldwide is infected with H. pylori and its prevalence is low in developed and high in developing countries. H. pylori is mainly acquired during childhood and transmission of the bacterium commonly proceeds from person to person, especially among family members. The most frequent transmission route is from the mother to children. Various gastrointestinal and extra-gastrointestinal diseases are reported to be associated with H. pylori in children and adolescents, but the strongest recommendation for testing and treating is introduced only with children and adolescents having peptic ulcer disease. Iron deficiency anemia and chronic immune thrombocytopenic purpura are also considered for testing and treating, but the effectiveness is somewhat controversial. Invasive diagnosis is recommended, whereas none of the available diagnostic tests have 100% accuracy for reliable diagnosis, and therefore at least two or more tests should be performed. Urea breath test is the most reliable among the non-invasive tests. Because the number of antibiotics-resistant H. pylori strains is increasing, it is desirable to conduct a drug susceptibility test before treatment and to select the corresponding regime. H. pylori has been proven to be a major cause of gastric cancer and 'screen-and-treat' strategies are recommended in communities at high risk of gastric cancer. However, the application to children and adolescents is controversial. An effective vaccine is desirable, but not yet available. Screen-and-treat for adolescents has started in a few areas in Japan, where conditions are well established. New prevention strategies for gastric cancer are awaited worldwide.

Gastric cancer in children and adolescents in Japan.

BACKGROUND: Very limited data are available on childhood gastric cancer. Using a retrospective survey and literature review, we assessed the clinical features of gastric cancer in children and adolescents. METHODS: We collected information on childhood gastric cancer from pediatricians of 518 hospitals that issue the title of "certified board pediatrician" approved by Japan Pediatric Society, using a questionnaire on background, diagnosis year, onset symptoms, tumor location, histology, nodular gastritis, Helicobacter pylori testing, treatment, and prognosis. Studies were collected using PubMed and the NPO Japan Medical Abstracts Society database. Data for childhood gastric cancer were abstracted from the Japanese Vital Statistics database. RESULTS: Of the 518 hospitals, 349 returned the questionnaire, which identified four patients. Literature review identified 77 cases of gastric cancer, and we analyzed data for 80 children <16 years old. Most patients were >10 years old, and there were no sex differences. Onset symptoms ranged from abdominal pain to non-localized. Sixteen of 44 children had a family history of cancer; 10 had a family history of gastric cancer. Histologically, approximately 80% had undifferentiated-type carcinoma. Prognosis was extremely poor, and two of three tested children were positive for H. pylori infection. Childhood gastric cancer death has been declining. CONCLUSIONS: Childhood gastric cancer is rare in Japan, and information on H. pylori in childhood gastric cancer patients is limited. Declining childhood gastric cancer rates may reflect the decreasing prevalence of infection but further study is necessary to clarify the relationship between H. pylori and gastric cancer.

Surface Morphology Analysis of Zirconium Dioxide Nanoparticles at 1200 K by Transmission Electron Microscopy.

Zirconium dioxide (ZrO2) nanoparticles were heated at 1200 K in a transmission electron microscope, and their surfaces were observed in situ via lattice imaging. The nanoparticles exhibited well-defined crystal habits while fluctuating the surface terrace structures. The stable surfaces and ridges were inferred from the fluctuation of the terraces, leading to the construction of the three-dimensional surface structures at 1200 K. By contrast, after the specimen cooled to room temperature, the surface fluctuation of the nanoparticles stopped and the crystal habit disappeared, implying that the crystal habit was maintained because of atomic diffusion during the surface fluctuation.

Randomized controlled trial: PPI-based triple therapy containing metronidazole versus clarithromycin as first-line treatment for Helicobacter pylori in adolescents and young adults in Japan.

BACKGROUND/AIMS: Treating Helicobacter pylori infection in young people is effective for preventing gastric cancer. This study compares the efficacy of triple therapies in adolescents and young adults in Japan. METHODS: This multicenter, randomized trial was conducted between February 2012 and March 2015. Infected participants were stratified into adolescents (13-19 years) and young adults (20-39 years). They were randomly assigned to a clarithromycin based (PAC) or metronidazole based (PAM) triple therapy for 1 week. RESULTS: Overall, 137 and 169 participants received the PAC and PAM treatments, respectively. In adolescents, the H. pylori eradication rates were 60.5% and 63.4% for PAC, and 98.3% and 100% for PAM in the intention-to-treat (ITT) and per-protocol (PP) analyses, respectively. In young adults, the eradication rates were 67.0% and 66.7% for PAC, and 95.5% and 96.3% for PAM in ITT and PP analyses, respectively. The eradication rate of PAM was significantly higher than that of PAC in both strata. No severe adverse events were observed. CONCLUSION: In Japan, PAM may be selected as a first-line treatment for young people with H. pylori if antibiotic susceptibility tests cannot be performed.