Height, weight, and body mass index associations with gastric cancer subsites

The causal association between obesity and gastric cancer and shared molecular signatures: a large-scale Mendelian randomization and multi-omics analysis

Purpose

While observational studies have identified obesity as a potential risk factor for gastric cancer, the causality remains uncertain. This study aimed to evaluate the causal relationship between obesity and gastric cancer and identify the shared molecular signatures linking obesity to gastric cancer.

Methods

A two-sample Mendelian randomization (MR) analysis was conducted using the GWAS data of body fat percentage (exposure, n = 331,117) and gastric cancer (outcome, n = 202,308). Bioinformatics and meta-analysis of multi-omics data were performed to identify key molecules mediating the causality. The meta-analysis of the plasma/serum proteome included 1,662 obese and 3,153 gastric cancer patients. Obesity and gastric cancer-associated genes were identified using seven common gene ontology databases. The transcriptomic data were obtained from TCGA and GEO databases. The Bioinformatic findings were clinically validated in plasma from 220 obese and 400 gastric cancer patients across two hospitals. Finally, structural-based virtual screening (SBVS) was performed to explore the potential FDA-approved drugs targeting the identified mediating molecules.

Results

The MR analysis revealed a significant causal association between obesity and gastric cancer (IVW, OR = 1.37, 95% CI:1.12-1.69, P = 0.0028), without pleiotropy or heterogeneity. Bioinformatic and meta-analysis of multi-omics data revealed shared TNF, PI3K-AKT, and cytokine signaling dysregulation, with significant upregulation of AKT1, IL-6, and TNF. The clinical study confirmed widespread upregulation of systemic inflammatory markers in the plasma of both diseases. SBVS identified six novel potent AKT1 inhibitors, including the dietary supplement adenosine, representing a potentially preventive drug with low toxicity.

Conclusion

Obesity causally increases gastric cancer, likely mediated by persistent AKT1/IL-6/TNF upregulation. As a potential AKT1 inhibitor, adenosine may mitigate the obesity-to-gastric cancer transition. These findings could inform preventive drug development to reduce gastric cancer risk in obesity.

Gastric Cancer Risk in Association with Underweight, Overweight, and Obesity: A Systematic Review and Meta-Analysis

This study aimed to investigate the risk of gastric cancer (GC) in abnormal body mass index (BMI) groups. A systematic search was carried out on Embase, PubMed/Medline, and Scopus from January 2000 to January 2023. The pooled risk ratio (RR) with a 95% confidence interval (CI) was assessed using a random-effect model. Thirteen studies with total of 14,020,031 participants were included in this systematic review. The pooled RR of GC was 1.124 (95% CI, 0.968-1.304, I²: 89.08%) in underweight class, 1.155 (95% CI, 1.051-1.270, I²: 95.18%) in overweight class, and in 1.218 (95% CI, 1.070-1.386, I²: 97.65%) obesity class. There is no difference between cardia and non-cardia gastric cancer, while non-Asian race and female gender have higher risk of cancer, as Meta-regression of obesity and overweight classes showed. These findings suggest that there is a positive association between excess body weight and the risk of GC, with a higher impact in women than men and in non-Asian than Asian populations. Since abnormal weight is tied to various diseases, including GC, healthcare experts, and policymakers should continue interventions aiming to achieve a normal BMI range.

Trends in gastric cancer mortality 1990-2019 in 36 countries worldwide, with predictions to 2025, and incidence, overall and by subtype

BACKGROUND

Gastric cancer (GC) incidence is declining heterogeneously worldwide. We aimed to calculate updated mortality trends for GC.

METHODS

We investigated time trends for selected countries using the World Health Organization database. We computed age-standardized mortality rates (ASMR) per 100,000 persons over the 1990-2019 period. We reported rates for the 2010-2014 and 2015-19 calendar periods, and the corresponding percent changes. We used joinpoint regression analysis to identify changes in the slope of mortality trends, and predict the number of deaths and rates for 2025. We also reported 2008-2012 incidence rates of cardia and noncardia GC.

RESULTS

Mortality trends from GC have been favorable since 1990 for all countries analyzed and the European Union (EU 27), in both sexes and all ages. GC mortality is predicted to decline in all countries for both sexes, except for French and US women aged 35-64 years, and Canadian men aged 35-64. The highest proportions of cardia GC were observed in Northern and Central Europe while the lowest ones in Southern and Eastern Europe. Elsewhere, the highest proportions were registered in countries with low incidence and mortality rates, whereas high-mortality countries showed lower proportions of cardia GC.

CONCLUSION

Observed and predicted GC mortality trends declined in most countries in both sexes, with few exceptions, likely due to the control of GC risk factors, in particular Hp infection.

Body shape phenotypes of multiple anthropometric traits and cancer risk: a multi-national cohort study

BACKGROUND

Classical anthropometric traits may fail to fully represent the relationship of weight, adiposity, and height with cancer risk. We investigated the associations of body shape phenotypes with the risk of overall and site-specific cancers.

METHODS

We derived four distinct body shape phenotypes from principal component (PC) analysis on height, weight, body mass index (BMI), waist (WC) and hip circumferences (HC), and waist-to-hip ratio (WHR). The study included 340,152 men and women from 9 European countries, aged mostly 35-65 years at recruitment (1990-2000) in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Cox proportional hazards regression was used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

After a median follow-up of 15.3 years, 47,110 incident cancer cases were recorded. PC1 (overall adiposity) was positively associated with the risk of overall cancer, with a HR per 1 standard deviation (SD) increment equal to 1.07 (95% confidence interval 1.05 to 1.08). Positive associations were observed with 10 cancer types, with HRs (per 1 SD) ranging from 1.36 (1.30-1.42) for endometrial cancer to 1.08 (1.03-1.13) for rectal cancer. PC2 (tall stature with low WHR) was positively associated with the risk of overall cancer (1.03; 1.02-1.04) and five cancer types which were not associated with PC1. PC3 (tall stature with high WHR) was positively associated with the risk of overall cancer (1.04; 1.03-1.05) and 12 cancer types. PC4 (high BMI and weight with low WC and HC) was not associated with overall risk of cancer (1.00; 0.99-1.01).

CONCLUSIONS

In this multi-national study, distinct body shape phenotypes were positively associated with the incidence of 17 different cancers and overall cancer.

Spatial Association between Gastric Cancer Mortality and Goiter in Sardinia

Background:

Gastric cancer (GC) is the third leading cause of cancer mortality worldwide. The incidence of GC varies between countries according to exposure to different risk factors. Hypothyroidism has been suggested as a potential GC risk factor. In Sardinia, Italy, the prevalence of endemic goiter is high and GC mortality is unevenly distributed. This ecological study aimed to investigate GC mortality and its relationship with hypothyroidism, adjusting for potential confounders.

Methods:

The spatial association between GC mortality and goiter (a proxy of hypothyroidism), diet, stature and pastoralism (a proxy of Helicobacter pylori infection), available at the aggregated level, was modelled in the island’s 377 municipalities, separately by sex, using geographically weighted regression (GWR).

Results:

The GC standardized mortality ratio ranged from 0.0 to 10.4 across municipalities. A hotspot of GC mortality was detected in the central mountainous area of Sardinia among males, positively associated with goiter (GWR estimate 0.213 ± 0.122), and the practice of sheep‒rearing (GWR estimate 0.127 ± 0.080), whereas a negative association with the diet score (GWR estimate 0.032 ± 0.034), and null for stature were found. No significant associations were found in females.

Conclusion:

Within the limitations of ecological studies goiter prevalence was an independent predictor of GC mortality in males.

Adult height is not associated with the risk of stomach cancer in a meta-analysis

Background

Adult height has been suggested as a biomarker for a wide range of diseases. However, there are epidemiologic inconsistencies regarding the association between adult height and stomach cancer risk.

Methods

We retrieved PubMed, EMBASE and Cochrane library databases to identify relevant studies assessing the relationship between height and risk of stomach cancer, published from inception to June 4, 2019. We pooled effect sizes for 5-cm height increments using a random-effect model and obtained the cumulative relative risk (RR) and 95% confidence interval (CI). Additionally, we performed subgroup investigation with sensitivity analysis and tested for publication bias using the Begg rank correlation test.

Results

We analyzed 11 studies involving 137,451 cases. The summary of effect size (95% CI) of stomach cancer for a 5-cm-increase in adult height was 0.99 (0.95-1.02). A "leave-one-out" sensitivity analysis indicated that the heterogeneity decreased by a half and the result showed significance (RR, 0.972; 95% CI, 0.948-0.997). Subgroup analyses found no significant associations, with one exception. The exception also depended entirely on one study. We found no significant publication bias (P=0.276).

Conclusions

Height is not associated with increased stomach cancer risk. Epidemiologic studies of potential confounders are needed to clarify the association.

All-cancer incidence in Tehranian adults: more than a decade of follow-up-results from the Tehran Lipid and Glucose Study

OBJECTIVES

To investigate the incidence rates for different malignancies and assess the risk factors for all-cancer incidence in Tehran.

STUDY DESIGN

Cohort study.

METHODS

This study consists of 8599 participants aged ≥ 30 years who were free of cancer (3935 men). Cancer diagnosis was based on pathology reports. Sex-stratified crude incidence rates and age-standardized incidence rates (ASRs) using Segi's method were calculated for all-cancers. Multivariate Poisson regression models were used to evaluate associations of potential risk factors, including sex, age, obesity status (body mass index [BMI]: 25-30 kg/m² as reference), education, smoking status, and diabetes mellitus with the incidence of cancers among the population. Incidence rate ratios (IRRs) with 95% confidence interval (CI) were also reported.

RESULTS

During a median follow-up of 13.9 years, there were 130 and 129 incident cancers for men and women, respectively; the corresponding ASRs were 356.1 and 243.6 per 100,000 person-years, respectively. The three most incident cancers among men were gastrointestinal (GI) (ASR = 127.5), hematopoietic (ASR = 99.5), and reproductive system malignancies (ASR = 46.3). The most common incident cancers in women were breast cancer (ASR = 92.1), GI (ASR = 65.4), and reproductive system malignancies (ASR = 16.8). Among risk factors for cancer incidence, age (IRR [95% CI]: 1.05 [1.03-1.06]) and having a BMI < 25 kg/m² (IRR [95% CI]: 1.38 [1.01-1.90]) had a statistically significant association with incident cancer.

CONCLUSIONS

The high rates of cancers in Tehran during more than a decade of follow-up calls for a need to define risk factors as well as to implement programs for early screening.

Anthropometric and reproductive factors and risk of esophageal and gastric cancer by subtype and subsite: Results from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort

Obesity has been associated with upper gastrointestinal cancers; however, there are limited prospective data on associations by subtype/subsite. Obesity can impact hormonal factors, which have been hypothesized to play a role in these cancers. We investigated anthropometric and reproductive factors in relation to esophageal and gastric cancer by subtype and subsite for 476,160 participants from the European Prospective Investigation into Cancer and Nutrition cohort. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox models. During a mean follow-up of 14 years, 220 esophageal adenocarcinomas (EA), 195 esophageal squamous cell carcinomas, 243 gastric cardia (GC) and 373 gastric noncardia (GNC) cancers were diagnosed. Body mass index (BMI) was associated with EA in men (BMI ≥30 vs. 18.5-25 kg/m2 : HR = 1.94, 95% CI: 1.25-3.03) and women (HR = 2.66, 95% CI: 1.15-6.19); however, adjustment for waist-to-hip ratio (WHR) attenuated these associations. After mutual adjustment for BMI and HC, respectively, WHR and waist circumference (WC) were associated with EA in men (HR = 3.47, 95% CI: 1.99-6.06 for WHR >0.96 vs. <0.91; HR = 2.67, 95% CI: 1.52-4.72 for WC >98 vs. <90 cm) and women (HR = 4.40, 95% CI: 1.35-14.33 for WHR >0.82 vs. <0.76; HR = 5.67, 95% CI: 1.76-18.26 for WC >84 vs. <74 cm). WHR was also positively associated with GC in women, and WC was positively associated with GC in men. Inverse associations were observed between parity and EA (HR = 0.38, 95% CI: 0.14-0.99; >2 vs. 0) and age at first pregnancy and GNC (HR = 0.54, 95% CI: 0.32-0.91; >26 vs. <22 years); whereas bilateral ovariectomy was positively associated with GNC (HR = 1.87, 95% CI: 1.04-3.36). These findings support a role for hormonal pathways in upper gastrointestinal cancers.

Body Mass Index and Risk of Intestinal Metaplasia: A Cohort Study

BACKGROUND

We examined the association between body mass index (BMI) and development of endoscopic intestinal metaplasia.

METHODS

This retrospective cohort study included 142,832 Korean adults free of endoscopic intestinal metaplasia and atrophic gastritis who underwent upper endoscopy at baseline and subsequent visits and were followed for up to 5 years. A parametric proportional hazards model was used to estimate the adjusted HR with 95% confidence interval (CI) for incident intestinal metaplasia.

RESULTS

In more than 444,719.1 person-years of follow-up, 2,281 participants developed endoscopic intestinal metaplasia (incidence rate, 5.1 per 1,000 person-years). Increased BMI categories were associated with increased risk of new-onset intestinal metaplasia in a dose-response manner. After adjustment for age, sex, center, year of screening exam, smoking status, alcohol intake, exercise, total calorie intake, history of diabetes and hypertension, and history of Helicobacter pylori infection, the multivariable adjusted HRs (95% CIs) for incident intestinal metaplasia comparing BMIs of <18.5, 23-24.9, 25.0-29.9, and >30 kg/m² with a BMI of 18.5-22.9 kg/m² were 0.84 (0.64-1.09), 1.03 (0.93-1.16), 1.07 (0.96-1.20), and 1.48 (1.20-1.83), respectively. These associations did not differ by clinically relevant subgroups. Risk of endoscopic atrophic gastritis also increased as the baseline BMI category increased.

CONCLUSIONS

In a large cohort of Korean men and women, obesity was independently associated with increased incidence of endoscopic atrophic gastritis and intestinal metaplasia.

IMPACT

Excessive adiposity appears to play a role in development of stomach precursor lesions of stomach cancer, requiring further studies to determine whether strategies to reduce obesity will also help reduce precancerous lesions and, in turn, gastric cancer.

Relationship between the Body Mass Index and Tumor Site Postoperative Complications and Prognosis in Gastric Adenocarcinoma

The impact of BMI on survival in gastric cancer (GC) is not clear. We sought to explore the relationship between BMI and tumor site, clinicopathologic characteristics, postoperative complications, and prognosis in GC patients. Patients who underwent gastrectomy for GC between January 2011 and June 2016 formed the study cohort (n = 827). Patients were divided into three groups according to the BMI (in kg/m2): “low” (<18.5), “normal” (18.5–24.9), and “high” (≥25.0). The preoperative level of albumin and hemoglobin in the low BMI group was lower than that in the high BMI or normal BMI group ( P < 0.05). The prevalence of gastric-cardia cancer in the high BMI group was significantly higher than that in the low BMI group ( P = 0.001). The prevalence of gastric-antrum cancer in the high BMI group was significantly lower than that in the low BMI group ( P = 0.001) and the normal BMI group ( P = 0.004). The BMI of patients with gastric-cardia cancer was significantly higher than that of patients with gastric-body cancer ( P = 0.018) and gastric-antrum cancer ( P < 0.001). There were no significant differences among the three groups in terms of tumor size, TNM stage, depth of tumor invasion, degree of tumor differentiation, resection margin, lymph node metastasis, or postoperative complications. BMI was not an independent factor that influenced the prognosis. We found a relationship between BMI and GC site. A low BMI may be associated with a poor prognosis and a high BMI may be related to a favorable prognosis. BMI was not an independent factor that influenced GC prognosis.

Gastric Cancer: an Evolving Disease

PURPOSE OF REVIEW

Prevalence of Helicobacter pylori, the primary risk factor for gastric cancer, is declining globally. Paralleling this trend, gastric cancer incidence is also decreasing. Historically, the populations most affected by this neoplasia have been males, Asians, and groups with low socioeconomic status. This review provides an update on recently published literature regarding changes in gastric cancer epidemiology.

RECENT FINDINGS

Gastric cancer incidence trends vary by age, sex, race/ethnicity, and tumor anatomical location. Overall incidence appears to be leveling off among young birth cohorts in Western populations, where H. pylori has declined considerably. The changes are more prominent for females and for tumors arising beyond the esophageal-gastric junction. The classical incidence pattern of gastric cancer is evolving. While uncertain, several hypotheses may explain the changing burden of disease. The mix of gastric cancer risk factors appears to be shifting, with H. pylori no longer the sole etiological driver. These changes may eliminate the previous predilection of males and lead to increases in overall gastric cancer rates. Analytical studies addressing known and novel factors related to major societal transitions may provide clues to understanding re-emergence of this serious public health problem.

The Changing Face of Noncardia Gastric Cancer Incidence Among US Non-Hispanic Whites

Background

The initial step for noncardia gastric carcinogenesis is atrophic gastritis, driven by either Helicobacter pylori infection or autoimmunity. In recent decades, the prevalence rates of these two major causes declined and increased, respectively, with changes in Western lifestyles. We therefore assessed gastric cancer incidence trends for US race/ethnic groups, 1995-2013.

Methods

Age-standardized rates (ASRs) from 45 North American Association of Central Cancer Tumor Registries were summarized by estimated annual percentage change (EAPC) and 95% confidence intervals (CIs). Age period cohort models supplemented standard descriptive techniques and projected future trends.

Results

There were 137 447 noncardia cancers in 4.4 billion person-years of observation. Among non-Hispanic whites, the ASR was 2.2 per 100 000 person-years, with an EAPC of -2.3% (95% CI = -2.0% to -2.6%). Notwithstanding this overall decline, EAPCs rose 1.3% (95% CI = 0.6% to 2.1%) for persons younger than age 50 years and fell -2.6% (95% CI = -2.4% to -2.9%) for older individuals. These converging trends manifested a birth cohort effect more pronounced among women than men, with incidence among women born in 1983 twofold (95% CI = 1.1-fold to 3.6-fold) greater than those born in 1951. Age interaction was also statistically significant among Hispanic whites, with slightly increasing vs decreasing EAPCs for younger and older individuals, respectively. Incidence declined regardless of age for other races. Current trends foreshadow expected reversals in both falling incidence and male predominance among non-Hispanic whites.

Conclusions

Dysbiosis of the gastric microbiome associated with modern living conditions may be increasing risk of autoimmune gastritis and consequent noncardia cancer. The changing face by age and sex of gastric cancer warrants analytical studies to identify potential causal mechanisms.

Diabetes mellitus and the risk of gastric cancer: a meta-analysis of cohort studies

Studies examining the relationship between diabetes mellitus (DM) and the risk of gastric cancer incidence or gastric cancer mortality have produced inconsistent results. The purpose of this study was to evaluate the evidence regarding the relationship between DM and subsequent gastric cancer incidence or gastric cancer mortality risk on the basis of cohort studies. A systematic search of articles in PubMed, EmBase, the Cochrane Library, and reference lists was conducted to identify relevant literature. Twenty-two cohort studies reporting data on 8,559,861 participants were included in the study. Overall, participants with DM had little or no change in the risk of gastric cancer, or gastric cancer mortality. There was no evidence of difference in the RR for gastric cancer between men and women. Participants with DM had a non-significant trend towards an increased risk of gastric cancer mortality in men. There was no significant difference between men and women for this relationship. Finally, although subgroup analysis suggested DM was associated with a significant impact on gastric cancer incidence and gastric cancer mortality risk in several specific populations, a significance based on gender difference was not observed. In conclusion, DM might increase the risk of gastric cancer in men when the study used standard incidence/mortality ratio as effect estimate. Further, DM were associated with higher risk of gastric cancer mortality in men if the mean age at baseline less than 55.0 years, used RR or HR as effect estimate, the study adjusted smoking or not, and the study not adjusted alcohol drinking.

Body mass index at adolescence and risk of noncardia gastric cancer in a cohort of 1.79 million men and women

BACKGROUND

This study assessed adolescent predictors of noncardia gastric cancer (NCGC) with a focus on the body mass index (BMI) in late adolescence.

METHODS

This study analyzed a cohort of 1,087,358 Israeli Jewish males and 707,212 Israeli Jewish females who underwent a compulsory physical examination between the ages of 16 and 19 years from 1967 to 2002. By linkage to the national cancer registry, participants were followed for NCGC through December 31, 2012. With a median follow-up of 23 years, 515 NCGC cases occurred (379 men and 136 women), and the median age was 47.0 years (interquartile range, 39.3-53.4 years). Multivariate-adjusted Cox regression was used to estimate hazard ratios (HRs) for NCGC according to the US Centers for Disease Control and Prevention BMI percentiles at the baseline (normal weight, 5th to <85th percentile; overweight, 85th to <95th percentile; and obesity, ≥95th percentile) as well as the country of birth, residential socioeconomic status (SES), and education.

RESULTS

In comparison with normal weight, adolescent obesity, but not overweight, was associated in both men and women with the risk of subsequent NCGC (unadjusted HR, 1.95; 95% confidence interval [CI], 1.25-3.06; adjusted HR, 1.78; 95% CI, 1.12-2.83). Immigration from the former Soviet Union (FSU), a low education level, and a low residential SES were also associated with the risk for NCGC with adjusted HRs of 2.67 (95% CI, 1.86-3.83), 1.85 (95% CI, 1.53-2.25), and 1.48 (95% CI, 1.13-1.93), respectively.

CONCLUSIONS

The findings suggest that adolescent obesity, but not overweight, is associated with an increased risk for NCGC. Immigration from the FSU, a low residential SES, and a low education level are also significantly associated with the risk for NCGC. Cancer 2018;124:356-63. © 2017 American Cancer Society.

A prospective appraisal of preoperative body mass index in D2-resected patients with non-metastatic gastric carcinoma and Siewert type II/III adenocarcinoma of esophagogastric junction: results from a large-scale cohort

Objective

To prospectively investigate associations of presurgical body mass index (BMI) with clinicopathological factors and its prognostic significance in radically D2-resected patients with non-metastasized gastric cancer (GC) and Siewert type II/III adenocarcinoma of esophagogastric junction (AEG).

Methods

A large prospective cohort consisting of radically-resected GC and AEG patients was analyzed. Follow-up was successful in 671 out of 700 patients, who were categorized into underweight (BMI<18.5), normal-weight (BMI=18.5-22.9), overweight (BMI=23-24.9), and obese (BMI≥25) groups according to Asian standards. BMI-associated factors were explored using multivariable logistic regression with adjustment. Cancer-specific survival analyses were conducted applying both univariable and multivariable Cox regression methods.

Results

Pre-operation, higher hemoglobin levels and smaller anemia proportions were observed in larger BMI groups. Higher BMI tended to be associated with higher neutrophil-lymphocyte ratios (NLRs). Patients with higher BMI had smaller tumors and more often stage I tumors, but longer surgical time and postsurgical stay. In multivariable analyses, higher hemoglobin levels, upper tumor location, poorer differentiation, and higher NLR were significantly associated with higher BMI. Overall, survival analyses revealed no significant role of BMI. However, in further stratifications after adjustment, compared to patients with normal BMI, obese patients had better survival in women, but worse in those with AEG; underweight was associated with reduced mortality risk in tumors differentiated well to moderately; overweight patients had increased death hazard when having thrombocytopenia.

Conclusion

Overall, preoperative BMI had limited prognostic significance in operated GC patients. However, under specific conditions (e.g., female, AEG, good differentiation, and thrombocytopenia), BMI might indicate postoperative survival.

Genetically predicted high body mass index is associated with increased gastric cancer risk

Epidemiological studies have linked body mass index (BMI) with risk of gastrointestinal cancers. However, for gastric cancer, the relationship is more controversial. In particular, it is unclear whether the observed association is due to confounding or bias inherent in conventional observational studies. To investigate whether BMI is causally associated with gastric cancer risk, we applied Mendelian randomization using individual-level data from 2631 gastric cancer cases and 4373 cancer-free controls. We derived a weighted genetic risk score (wGRS) using 37 BMI-associated genetic variants as an instrumental variable. We used logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for associations between genetically predicted BMI and gastric cancer risk. We observed that higher genetically determined BMI was associated with increased gastric cancer risk (per standard deviation (SD) increase in the wGRS: OR=1.07, 95% CI: 1.02-1.13, P=4.94 × 10^-3). Compared with individuals in the bottom tertile of the BMI wGRS, those in the top tertile had 1.14-fold (95% CI: 1.01-1.29) increased risk of developing gastric cancer. Sensitivity analyses using alternative causal inference measures demonstrated consistent association. Our study indicated that genetically high BMI was associated with increased gastric cancer risk, suggesting that high BMI may have a causal role in the etiology of gastric cancer.

Diabetic biomarkers and the risk of proximal or distal gastric cancer

BACKGROUND AND AIM

The role of diabetes mellitus as a risk factor for gastric cancer has been controversial. We studied the association between diabetic biomarkers and the risk of gastric cancer and whether these associations depend on cancer location.

METHODS

In this retrospective cohort study with subjects with negative initial esophagogastroduodenoscopy findings (n = 23 218) during a routine health checkup, we measured fasting glucose and insulin levels, calculated the homeostatic model assessment insulin resistance (HOMA-IR) values, and analyzed the risk of gastric cancer in relation to diabetic biomarker tertiles and the presence of diabetes mellitus.

RESULTS

The incidence rate of gastric cancer was 9.7 per 10 000 person-years during the mean 6.8-year follow up. Patients with diabetes, higher fasting glucose levels, or higher HOMA-IR levels were older; men, current smokers, and heavy alcohol consumers represented larger proportions of these groups. They also had high body mass index and hemoglobin A1c more often. In the multivariate-adjusted Cox regression analyses, the incidence of gastric cancer was not significantly associated with diabetes mellitus or higher diabetic biomarker levels. Compared with normal glucose levels, lower glucose levels were significantly associated with an increased risk of distal gastric cancer. The hazard ratio for fasting glucose level tertile 1 was 2.39 (95% confidence interval, 1.48-3.85) (reference, tertile 2). Lower glucose levels were not associated with a risk of proximal gastric cancer, compared with a normal glucose level.

CONCLUSIONS

Our findings suggest that fasting glucose levels have a different effect on distal and proximal gastric cancers.

Stomach cancer burden in Central and South America

RATIONALE AND OBJECTIVE

Stomach cancer mortality rates in Central and South America (CSA) are among the highest in the world. We describe the current burden of stomach cancer in CSA.

METHODS

We obtained regional and national-level cancer incidence data from 48 population-based registries (13 countries) and nation-wide cancer deaths from WHO's mortality database (18 countries). We estimated world population age-standardized incidence (ASR) and mortality (ASMR) rates per 100,000 and estimated annual percent change to describe time trends.

RESULTS

Stomach cancer was among the 5 most frequently diagnosed cancers and a leading cause of cancer mortality. Between CSA countries, incidence varied by 6-fold and mortality by 5-6-fold. Males had up to 3-times higher rates than females. From 2003 to 2007, the highest ASRs were in Chile, Costa Rica, Colombia, Ecuador, Brazil and Peru (males: 19.2-29.1, females: 9.7-15.1). The highest ASMRs were in Chilean, Costa Rican, Colombian and Guatemalan males (17.4-24.6) and in Guatemalan, Ecuadorian and Peruvian females (10.5-17.1). From 1997 to 2008, incidence declined by 4% per year in Brazil, Chile and Costa Rica; mortality declined by 3-4% in Costa Rica and Chile. 60-96% of all the cancer cases were unspecified in relation to gastric sub-site but, among those specified, non-cardia cancers occurred 2-13-times more frequently than cardia cancers.

CONCLUSION

The variation in rates may reflect differences in the prevalence of Helicobacter pylori infection and other risk factors. High mortality may additionally reflect deficiencies in healthcare access. The high proportion of unspecified cases calls for improving cancer registration processes.

Artemether inhibits human gastric cancer cell proliferation in vitro and tumor growth in tumor bearing mice

AIM: To investigate the inhibitory effect of artemether (ART) on cell proliferation and apoptosis in human gastric adenocarcinoma cell line and tumor growth in tumor bearing mice.

METHODS: The inhibitory effect of ART on cell proliferation in human gastric cancer cell line SGC-7901 was detected by MTT assays, and the effects on cell cycle and apoptosis were evaluated by flow cytometry. The anti-tumor effect of ART was observed in tumor bearing nude mice by measuring mice weight and diameter and calculating tumor volume and tumor growth inhibition rate. The mechanism underlying the effects of ART on cell proliferation and apoptosis was explored by Western blot.

RESULTS: MTT assays showed that ART inhibited SGC-7901 cell growth in a time- and dosage-dependent manner (P < 0.05). The results of flow cytometry demonstrated that ART treatment induced cell arrest at G₀/G₁ phase and cell apoptosis. Medium- and high-dose ART had significant anti-tumor effects in human gastric cancer cell bearing mice, and the inhibition rates were 34.5% and 41.0%, respectively. ART treatment up-regulated proliferating cell nuclear antigen (PCNA) and B-cell lymphoma-2 (Bcl-2) expression, and down-regulated Bcl-2 associated X protein (Bax) expression (P < 0.05).

CONCLUSION: ART can inhibit proliferation and induce arrest cell cycle and apoptosis in SGC-7901 cells in vitro as well as tumor growth in vivo.