Height, weight, menstrual and reproductive factors and risk of gastric cancer among Japanese postmenopausal women: analysis by subsite and histologic subtype

Obesity at early adulthood increases risk of gastric cancer from the Health Examinees-Gem (HEXA-G) study

Emerging evidence has indicated a possible link between obesity in early life with subsequent cancer risks, but its association with gastric cancer remains unknown. This study aimed to investigate the association of obesity at ages 18-20 and 35 with the later risk of gastric cancer among the Korean population. Included were 122,724 individuals who participated in the large-scale prospective cohort study, the Health Examinees-Gem (HEXA-G) study, during 2004-2017. Multivariable Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for gastric cancer risk associated with body mass index (BMI) at ages 18-20 and 35 years. During a mean follow-up period of 8.6±2.1 years, a total 927 gastric cancer cases (531 men and 396 women) were identified. When compared to normal BMI (18.5-23.0 kg/m2), obesity (BMI ≥30 kg/m2) at age 35 was significantly associated with increased risk of gastric cancer later in life among total participants (HR 1.94, 95% CI 1.26-2.97, p 0.01). When analyzed separately by sex, obesity at 35 years of age was significantly associated with increased risk of gastric cancer among both men (HR 1.79, 95% CI 1.02-3.13, p 0.05) and women (HR 2.35, 95% CI 1.21-4.60, p 0.02). No significant associations were found for obesity at late adolescence in both men and women. Our findings suggest that obesity in early adulthood may be associated with an increased risk of gastric cancer. The results may aid in understanding the etiology of GC in a population with a divergent trend of gastric cancer.

Nationwide cohort study: cholesterol level is inversely related with the risk of gastric cancer among postmenopausal women

BACKGROUND

Recent studies showed inverse relationship between hypercholesterolemia and the risk of gastric cancer, especially among male. However evidence among female is inconsistent. We aimed to investigate the relationship between cholesterol level and the risk of gastric cancer among female according to menopausal status.

METHODS

We analyzed the data from a population-based prospective cohort of female ≥ 30 years old who underwent cancer screening and general health screening provided by the Korean National Health Insurance Corporation in 2009. Under quartile stratification of the level of cholesterol components, we calculated the hazard ratio (HR) for gastric cancer incidence until 2018 for each level group according to the menopausal status at 2009.

RESULTS

Among total 2,722,614 individuals, 17,649 gastric cancer cases developed after mean 8.26 years of follow-up (premenopausal 3746/1180666; postmenopausal 13,903/1541948). Total cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) showed inverse relationship with the risk of gastric cancer among postmenopausal women (adjusted HR (95% confidence interval) for the highest quartile vs. lowest quartile and p-for-trend: 0.88 (0.84-0.92) and < 0.001 for total cholesterol; 0.89 (0.85-0.92) and < 0.001 for HDL-C; 0.92 (0.89-0.97) and 0.001 for LDL-C), whereas none showed statistically significant risk relationship among premenopausal women. Triglyceride was not independently related with gastric cancer risk among both pre- and postmenopausal women.

CONCLUSIONS

Cholesterol levels, including total cholesterol, HDL-C, and LDL-C, are inversely related with the risk of gastric cancer among postmenopausal women, but not among premenopausal women.

Body fatness at a young age and risks of eight types of cancer: systematic review and meta-analysis of observational studies

The associations between body fatness at a young age (childhood, adolescence and young adulthood; age ≤ 30 years) and diffuse large B-cell lymphoma (DLBCL), oesophageal adenocarcinoma, gastric cardia cancer, hepatocellular carcinoma, multiple myeloma, pancreatic cancer, renal cell cancer and thyroid cancer remain inconclusive. We performed a comprehensive systematic literature review and meta-analysis of observational studies to clarify the associations between body fatness at a young age and the risks of these cancers. PubMed and Web of Science databases were searched for relevant observational studies. Fifty-six articles yielded data on 27,559 cancer cases, including 3,170 DLBCL, 1,491 oesophageal adenocarcinoma, 1,103 gastric cardia cancer, 1,067 hepatocellular carcinoma, 3,090 multiple myeloma, 7,220 pancreatic cancer, 6,212 renal cell cancer and 4,206 thyroid cancer cases. Each 5 kg m^-2 increase in body mass index at a young age was positively associated with DLBCL (relative risk [RR] 1.21, 95% confidence interval [CI] 1.09, 1.35), oesophageal adenocarcinoma (RR 1.88, 95% CI 1.37, 2.57), gastric cardia cancer (RR 1.59, 95% CI 1.15, 2.21), hepatocellular carcinoma (RR 1.31, 95% CI 1.13, 1.51), multiple myeloma (RR 1.23, 95% CI 1.15, 1.30), pancreatic cancer (RR 1.17, 95% CI 1.11, 1.24), renal cell cancer (RR 1.22, 95% CI 1.16, 1.28) and thyroid cancer (RR 1.12, 95% CI 1.07, 1.17). In summary, higher body fatness at a young age increases the risks of developing various types of cancer later in life. Prevention of overweight and obesity in children, adolescents and young adults should therefore be emphasized to reverse the obesity epidemic and thereby avoid further increases in the burden of cancer attributed to excess body fatness.

Male non-insulin users with type 2 diabetes mellitus are predisposed to gastric corpus-predominant inflammation after H. pylori infection

BACKGROUND

Both H. pylori infection and diabetes increase the risk of gastric cancer. This study investigated whether patients with type 2 diabetes mellitus (T2DM) and H. pylori infection had more severe corpus gastric inflammation and higher prevalence of precancerous lesions than non-diabetic controls.

METHODS

A total of 797 patients with type 2 diabetes mellitus were screened for H. pylori, of whom 264 had H. pylori infection. Of these patients, 129 received esophagogastroduodenoscopy to obtain topographic gastric specimens for gastric histology according to the modified Updated Sydney System, corpus-predominant gastritis index (CGI), Operative Link on Gastritis Assessment, and Operative Link on Gastric Intestinal Metaplasia Assessment. Non-diabetic dyspeptic patients who had H. pylori infection confirmed by esophagogastroduodenoscopy were enrolled as controls.

RESULTS

The male as well as total T2DM patients had higher acute/chronic inflammatory and lymphoid follicle scores in the corpus than non-diabetic controls (p < 0.05). In contrast, the female T2DM patients had higher chronic inflammatory scores in the antrum than the controls (p < 0.05). In T2DM patients, the males had significantly higher rates of CGI than the females (p < 0.05). Multivariate logistic regression analysis showed that male patients (odds ratio: 2.28, 95% confidence interval: 1.11-4.69, p = 0.025) and non-insulin users (odds ratio: 0.33, 95% confidence interval: 0.15-0.74, p = 0.007) were independent factors for the presence of CGI in the H. pylori-infected patients with type 2 diabetes mellitus.

CONCLUSIONS

Patients with type 2 diabetes mellitus and H. pylori infection had more severe corpus gastric inflammation than non-diabetic controls. Moreover, male gender and non-insulin users of T2DM patients were predisposed to have corpus-predominant gastritis after H. pylori infection.

TRIAL REGISTRATION

ClinicalTrial: NCT02466919 , retrospectively registered may 17, 2015.

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.

Menstrual and Reproductive Factors and Risk of Gastric and Colorectal Cancer in Spain

Background

Sex hormones play a role in gastric cancer and colorectal cancer etiology, however, epidemiological evidence is inconsistent. This study examines the influence of menstrual and reproductive factors over the risk of both tumors.

Methods

In this case-control study 128 women with gastric cancer and 1293 controls, as well as 562 female and colorectal cancer cases and 1605 controls were recruited in 9 and 11 Spanish provinces, respectively. Population controls were frequency matched to cases by age and province. Demographic and reproductive data were directly surveyed by trained staff. The association with gastric, colon and rectal cancer was assessed using logistic and multinomial mixed regression models.

Results

Our results show an inverse association of age at first birth with gastric cancer risk (five-year trend: OR = 0.69; p-value = 0.006). Ever users of hormonal contraception presented a decreased risk of gastric (OR = 0.42; 95%CI = 0.26–0.69), colon (OR = 0.64; 95%CI = 0.48–0.86) and rectal cancer (OR = 0.61; 95%CI = 0.43–0.88). Postmenopausal women who used hormone replacement therapy showed a decreased risk of colon and rectal tumors. A significant interaction of educational level with parity and months of first child lactation was also observed.

Conclusion

These findings suggest a protective role of exogenous hormones in gastric and colorectal cancer risk. The role of endogenous hormones remains unclear.

Association Between Colorectal Cancer and Atherosclerotic Diseases: A Study Using a National Inpatient Database in Japan

BACKGROUND

Both colorectal neoplasms and atherosclerosis can be induced by common visceral fat accumulation. However, the association between these diseases at the advanced stage, colorectal cancer and cardiovascular/cerebrovascular diseases, has not been elucidated.

AIMS

This study aimed to investigate the association between colorectal cancer and vascular diseases in relation to obesity and metabolic disorders, using a nationwide database of hospitalized patients in Japan. We used non-cardiac gastric cancer patients as a reference, because they were considered to be neutral for obesity or metabolic disorders.

METHODS

We identified 54,591 patients with colorectal cancer and 19,565 patients with gastric cancer from the Diagnosis Procedure Combination database. The data collected included: sex; age; body mass index (BMI); smoking status; comorbidity; and medication data, comprising hypertension, diabetes, hyperlipidemia, coronary artery disease, and stroke. We compared these data in a cross-sectional setting by multivariate analyses.

RESULTS

Multivariate logistic regression analyses showed that female sex, increased BMI, hypertension [odds ratio (OR) 1.11; 95 % confidence interval (CI) 1.07-1.15; P < 0.0001], and diabetes (OR 1.17; 95 % CI 1.12-1.23; P < 0.0001) were more associated with colorectal cancer than with gastric cancer. Smoking, aspirin use (OR 0.85; 95 % CI 0.79-0.92; P < 0.0001), and coronary artery disease (OR 0.90; 95 % CI 0.86-0.95; P = 0.0001) were inversely associated with colorectal cancer.

CONCLUSIONS

Obesity and metabolic disorders were more associated with colorectal cancer than with non-cardiac gastric cancer, while coronary artery disease (CAD) was inversely associated. Some mechanisms involving separate populations of colorectal cancer and CAD under visceral fat accumulation might be suggested.

A review of the epidemiology of Barrett's oesophagus and oesophageal adenocarcinoma

While the incidence rates of many cancers have decreased in past decades, the incidence of oesophageal adenocarcinoma continues to increase. The only known precursor for oesophageal adenocarcinoma is Barrett's oesophagus. Studies conducted have identified white race, male sex, GORD, cigarette smoking, obesity, and the absence of Helicobacter pylori status as risk factors for oesophageal adenocarcinoma. Other potential associations include dietary factors and the absence of non-steroidal anti-inflammatory drug use. Many individual studies have been limited by sample size and several meta-analyses have pooled data from studies to address this limitation. In this review we present a synthesis of these studies and summarize current knowledge of risk factors for both oesophageal adenocarcinoma and Barrett's oesophagus.

Obesity at adolescence and gastric cancer risk

BACKGROUND AND OBJECTIVE

During the last few decades, prevalence of obesity has risen rapidly worldwide, markedly in children and adolescents. Epidemiologic studies have associated obesity to several cancer types, yet little is known for the effect of early life exposure to obesity on cancer risk in later life, especially in gastric cancer. Thus, the present study aimed to investigate the association of body mass index (BMI) of adolescence and the risk of gastric cancer.

METHODS

A multicenter case-control study was conducted between 2010 and 2014 in Korea with 1,492 incident gastric cancer cases and 1,492 controls matched by age and sex. The BMI at age 18 was calculated by using weight and height from questionnaire. The association with the risk of gastric cancer was evaluated using odds ratios by logistic regression model adjusted for potential confounding factors.

RESULTS

Compared with BMI 21.75 kg/m(2), higher BMI at age 18 was associated with higher risk of gastric cancer showing a nonlinear, threshold effect. Statistically significant odds ratio was observed in men with BMI higher than 25.3 kg/m(2) (OR 1.13, 95 % CI 1.01-1.27) and in women with BMI 25.3 kg/m(2) and above (OR 1.25, 95 % CI 1.01-1.55).

CONCLUSION

Similar to some other cancer types, overweight or obese in adolescence was found to be associated with the increased risk of gastric cancer. The results imply for stratified approach of tactics in prevention of gastric cancer in different population.

Oxytocin has therapeutic effects on cancer, a hypothesis

Oxytocin (OT) is the first peptide hormone structurally assessed and chemically synthesized in biologically active form. This hormone acts as an important factor in a human reproductive system particularly during pregnancy and lactation in women. So far, different therapeutic roles for OT have been identified as a spectrum from central and peripheral actions on male and female reproductive systems, circulatory system, musculoskeletal system, etc. Some in vitro and in vivo studies also revealed that OT is responsible for bivariate biological functions involved in cancer as following. By activating OT receptor in tumoral cells, OT enacts as a growth regulator, whether activator or inhibitor. Regarding the increase of OT in some conditions such as breastfeeding, exercise, and multiparity, we can relate the effect of these conditions on cancer with OT effects. Based on this hypothesis, we present a review on the effects of this neuropeptide on various types of cancer and also the influence of these conditions on the same cancer.

Dimovski A. Natural antioxidants in cancer prevention

It is well known that oxidative stress is an inevitable event in aerobic life. When our cells use oxygen to create energy, a variety of reactive oxygen (ROS) and nitrogen species (RNS) are generated. These species could attack DNA directly and form mutagenic lesions afterwards. According to the oxidative stress hypothesis of aging, the oxidative damage to critical molecules accumulates over the life period and could ultimately impair the body’s function. Moreover, severe oxidative stress causes mutations of tumor suppressor genes, known as one of the initial events in carcinogenesis. Furthermore, it could also play a crucial role in the promotion of the multi-step carcinogenesis. On the other hand, the human body possesses a number of mechanisms that counteract oxidative stress by producing antioxidants in situ, or externally supplied them through foods and/or supplements. Indeed, a considerable amount of laboratory evidence from chemical, cell culture, and animal studies indicates that antioxidants may slow down or possibly prevent the cancer development. Yet, the information from recent cohort, case-control and/or ecological studies is less clear. Therefore, the objectives of this review are to compile a compendium of studies, and to identify effective and promising natural antioxidant interventions.

Genetic susceptibility factors on genes involved in the steroid hormone biosynthesis pathway and progesterone receptor for gastric cancer risk

Background

The objective of the study was to investigate the role of genes (HSD3B1, CYP17A1, CYP19A1, HSD17B2, HSD17B1) involved in the steroid hormone biosynthesis pathway and progesterone receptor (PGR) in the etiology of gastric cancer in a population-based two-phase genetic association study.

Methods

In the discovery phase, 108 candidate SNPs in the steroid hormone biosynthesis pathway related genes and PGR were analyzed in 76 gastric cancer cases and 322 controls in the Korean Multi-Center Cancer Cohort. Statistically significant SNPs identified in the discovery phase were re-evaluated in an extended set of 386 cases and 348 controls. Pooled- and meta-analyses were conducted to summarize the results.

Results

Of the 108 SNPs in steroid hormone biosynthesis pathway related genes and PGR analyzed in the discovery phase, 23 SNPs in PGR in the recessive model and 10 SNPs in CYP19A1 in the recessive or additive models were significantly associated with increased gastric cancer risk (p<0.05). The minor allele frequencies of the SNPs in both the discovery and extension phases were not statistically different. Pooled- and meta-analyses showed CYP19A1 rs1004982, rs16964228, and rs1902580 had an increased risk for gastric cancer (pooled OR [95% CI] = 1.22 [1.01–1.48], 1.31 [1.03–1.66], 3.03 [1.12–8.18], respectively). In contrast, all PGR SNPs were not statistically significantly associated with gastric cancer risk.

Conclusions

Our findings suggest CYP19A1 that codes aromatase may play an important role in the association of gastric cancer risk and be a genetic marker for gastric cancer susceptibility.

Sex hormones, hormonal interventions, and gastric cancer risk: a meta-analysis

Estrogens may influence gastric cancer risk, but published studies are inconclusive. We therefore carried out a meta-analysis addressing the associations of gastric cancer in women with menstrual and reproductive factors and with use of estrogen- and antiestrogen-related therapies. Searches of PubMed up to June, 2011 and review of citations yielded a total of 28 independent studies, including at least one exposure of interest. Random effects pooled estimates of relative risk (RR) and corresponding 95% CIs were calculated for eight exposures reported in at least five studies, including: age at menarche, age at menopause, years of fertility, parity, age at first birth, oral contraceptive use, hormone replacement therapy (HRT), and tamoxifen treatment. Longer years of fertility (RR = 0.74, 95% CI: 0.63-0.86) and HRT (RR = 0.77; 95% CI: 0.64-0.92) were each associated with decreased gastric cancer risk. Conversely, tamoxifen treatment was associated with increased risk (RR = 1.82; 95% CI: 1.39-2.38). The other five exposures were not significantly associated. Our analysis supports the hypothesis that longer exposure to estrogen effects of either ovarian or exogenous origin may decrease risk of gastric cancer. Additional studies are warranted to extend this finding and to identify the underlying mechanisms.

Reproductive factors and risk of oesophageal and gastric cancer in the Million Women Study cohort

Background:

Hormonal factors may influence risk for upper gastrointestinal cancers in women. We examined risk of oesophageal and gastric cancers in relation to reproductive factors in a large UK cohort, the Million Women Study.

Methods:

Among 1 319 409 women aged on average 56 years at recruitment, 1186 incident cancers of the oesophagus and 1194 of the stomach were registered during 11.9 million person-years’ observation. Adjusted relative risks (RRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models.

Results:

Risks of both oesophageal and gastric cancer were significantly higher in postmenopausal than in pre- or peri-menopausal women (RRs 1.46, 1.07–2.00 and 1.59, 1.15–2.20, respectively; P⩽0.01 for both); and, among postmenopausal women, risk was higher the younger women were at menopause (RR, 95% CI per 5 years younger at menopause 1.18, 1.05–1.34 for oesophageal cancer and 1.18, 1.04–1.34 for stomach cancer, P_trend=0.01 for both). For factors relating to childbearing, including women's age at first birth, their number of children, and breastfeeding history, the only significant association was a higher risk of oesophageal cancer in nulliparous, compared with parous, women (RR 1.31, 1.11–1.55; P=0.002). When risks for squamous cell and adenocarcinomas of the oesophagus were compared, most did not differ significantly, but statistical power was limited.

Conclusion:

Both oesophageal and gastric cancer risks appeared to be related to menopausal status and age at menopause, but there was little consistent evidence for associations with factors related to childbearing.

Higher parity associated with higher risk of death from gastric cancer

AIM: To examine the association between parity and gastric cancer (the cases are almost all premenopausal women) risk in a cohort of young parous women.

METHODS: The study cohort consisted of all women with a record of a first and singleton childbirth in the Birth Register between 1978 and 1987. We tracked each woman from the time of her first childbirth to December 31, 2008. Their vital status was ascertained by linking records to the computerized mortality database. Cox proportional hazard regression models were used to estimate hazard ratios of death from gastric cancer associated with parity.

RESULTS: There were 1090 gastric cancer deaths (85.87% of them were premenopausal) during 33 686 828 person-years of follow-up. The mortality rate of gastric cancer was 3.24 cases per 100 000 person-years. A trend of increasing risk of gastric cancer was seen with increasing parity. The adjusted hazard ratio was 1.24 [confidence interval (95% CI): 1.02-1.50] for women who had borne two to three children, and 1.32 (95% CI: 1.01-1.72) for women with four or more births, when compared with women who had given birth to only one child.

CONCLUSION: These results suggest that higher parity may increase the risk of death from gastric cancer among premenopausal women.

Menstrual and reproductive factors, exogenous hormone use, and gastric cancer risk in a cohort of women from the European Prospective Investigation Into Cancer and Nutrition

The worldwide incidence of gastric adenocarcinoma (GC) is lower in women than in men. Furthermore, cancer patients treated with estrogens have been reported to have a lower subsequent risk of GC. The authors conducted a prospective analysis of menstrual and reproductive factors, exogenous hormone use, and GC in 335,216 women from the European Prospective Investigation Into Cancer and Nutrition, a cohort study of individuals aged 35-70 years from 10 European countries. After a mean follow-up of 8.7 years (through 2004), 181 women for whom complete exposure data were available developed GC. Adjusted hazard ratios and 95% confidence intervals were estimated using Cox proportional hazards models. All statistical tests were 2-sided. Women who had ovariectomy had a 79% increased risk of GC (based on 25 cases) compared with women who did not (hazard ratio = 1.79, 95% confidence interval: 1.15, 2.78). Total cumulative years of menstrual cycling was inversely associated with GC risk (fifth vs. first quintile: hazard ratio = 0.55, 95% confidence interval: 0.31, 0.98; P(trend) = 0.06). No other reproductive factors analyzed were associated with risk of GC. The results of this analysis provide some support for the hypothesis that endogenous ovarian sex hormones lower GC incidence in women.

Epidemiological aspects of gastric adenocarcinoma: are predictive diagnostics and targeted preventive measures possible?

The incidence of gastric cancer has witnessed major changes over the past decades. Until recently, gastric cancer was a common malignancy in most countries. A striking decline in incidence in most Western populations has occurred since the 1970s, and elucidating the detailed causes for this trend can potentially be of great value for targeted preventive measures. Furthermore, it can add to the understanding of malignant disease and prevention in general. Moreover, the absolute number of cases worldwide is predicted to increase during many years to come. Gastric cancer is typically diagnosed at an advanced stage in symptomatic patients, and there are often no effective curative or palliative or therapeutic options. This fact highlights the need for research aiming to increase our understanding of the etiology of this cancer, facilitating the design of successful targeted preventive strategies for different populations. The future outlook in terms of decreasing gastric cancer deaths would be to identify such intelligent diagnostic tools. In this article, we present a summary of the epidemiology of gastric cancer, with special focus on its etiology.

The association of menstrual and reproductive factors with upper gastrointestinal tract cancers in the NIH-AARP cohort

BACKGROUND

In most populations, incidence rates of upper gastrointestinal (UGI) tract cancers (head and neck, esophagus, and stomach) are higher among men than among women. Established risk factors do not appear to explain these differences, suggesting a possible role for sex hormones.

METHODS

201,506 women of the NIH-AARP Diet and Health cohort completed a questionnaire in 1995-1996. Hazard ratios and 95% confidence intervals were estimated from Cox proportional hazards models.

RESULTS

During follow-up through 2003, 162 incident adenocarcinomas (ACs; esophagus, N = 25, and stomach, N = 137) and 353 incident squamous cell carcinomas (SCCs; head and neck, n = 297, and esophagus, N = 56) occurred. Among examined exposures, older age at menopause was associated inversely with SCC (P(trend) across categories = .013) but not AC (P(trend) = .501). Use of menopausal hormone therapy (MHT) was significantly associated with lower risk of SCC (hazard ratio [HR] = 0.77, 0.62-0.96) and nonsignificantly associated with lower risk of AC (HR = 0.81, 0.59-1.12). A subset (N = 127,386) of the cohort completed a more detailed MHT questionnaire a year after baseline. In 74,372 women with intact uteri, ever use of estrogen-progestin MHT conferred 0.47 (0.30-0.75) times the risk for SCC and 0.52 (0.26-1.07) times the risk for ACC. In 51,515 women with a hysterectomy before baseline, we found no associations between use of estrogen MHT and AC or SCC.

CONCLUSIONS

Higher estrogen and progesterone levels may be related inversely to UGI cancers and in this way help explain lower incidence rates in women compared with men.

Reproductive and sex hormonal factors and oesophageal and gastric junction adenocarcinoma: a pooled analysis

BACKGROUND

The rapidly rising incidence and the striking male predominance are as yet unexplained features of oesophageal and gastric junction adenocarcinoma. Few and underpowered studies have examined the impact of female reproductive factors on risk of these adenocarcinomas in women. We therefore pooled data on women from four population-based case-control studies to examine the association of female reproductive and sex hormonal factors with oesophageal and gastric junction adenocarcinoma.

METHODS

Data on women from case-control studies conducted in Ireland, the United Kingdom (UK), Australia and United States of America (USA) were pooled. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for a range of reproductive factors, adjusted for age, study and major risk factors for oesophageal and gastric junction adenocarcinoma.

RESULTS

We included 218 cases and 862 controls. Among parous women, a reduced risk of oesophageal and gastric junction adenocarcinoma was found after breastfeeding (OR=0.58, 95% CI=0.37-0.92) and the risk decreased with increased duration of breastfeeding (>12 months OR=0.42, 95% CI=0.23-0.77). The endogenous reproductive factors such as parity, menstruation, history of pregnancy and the exogenous factors such as use of oral contraceptives and of hormone replacement therapy were not statistically significantly associated with oesophageal and gastric junction adenocarcinoma.

CONCLUSION

Our findings suggest that breastfeeding is associated with a decreased risk of oesophageal and gastric junction adenocarcinoma. The potential mechanism of this association warrants further investigation.

Sex differences in the incidence of gastrointestinal adenocarcinoma in Sweden 1970-2006

BACKGROUND

Oesophageal and gastric adenocarcinoma share a male predominance not seen for other adenocarcinomas of the gastrointestinal tract. These sex differences are not explained by known risk factors. An endogenous factor, such as premenopausal oestrogen exposure, may act protectively in favour of women and might be detected by scrutinising sex ratios and incidence rates stratified by age.

METHODS

The Swedish Cancer Register was used to collect primary oesophageal, gastric cardia, non-cardia gastric, colonic and pancreatic adenocarcinoma cases aged 25-84, during the study period of 1970-2006. Cases were divided into five-year age groups and crude incidence rates and male: female ratios were calculated. Evaluating potential time period effect, the corresponding results from 1970-1986 and 1987-2006 were also derived.

RESULTS

The sex ratio for oesophageal adenocarcinoma ranged from approximately 10:1 to 4:1, presenting a seemingly consistent decline with age. The sex ratio for non-cardia gastric adenocarcinoma, however, increased with age to reach 2:1 at a point one to two decades after menopause, where the ratio levelled off and eventually declined. There was no discernible time period effect concerning any type of adenocarcinoma. The ratios for gastric cardia, colonic and pancreatic adenocarcinoma were stable with age.

CONCLUSION

This study indicates separate patterns of age-dependency of the sex difference in oesophageal and non-cardia gastric adenocarcinoma incidence. The non-cardia gastric adenocarcinoma pattern might be due to a protective effect during premenopausal years for the female population, while the seemingly steady decline in sex ratio in oesophageal adenocarcinoma indicates a mechanism independent of menopause.

Overweight, obesity and gastric cancer risk: results from a meta-analysis of cohort studies

The relationship between excess body weight and gastric cancer risk has not been well studied to date. We therefore carried out a systematic review and meta-analysis of published cohort studies to evaluate the association between excess body weight and gastric cancer risk. An electronic search of the MEDLINE, PubMed, EMBASE and Academic Search Premier (EBSCO) databases, which contain articles published from 1950 onwards, was conducted in order to select studies for this meta-analysis. Ten studies with a total number of 9492 gastric cancer cases and a studied population of 3,097,794 were identified. Overall, excess body weight [body mass index (BMI)25] was associated with an increased risk of gastric cancer [odds ratio (OR)=1.22; 95% confidence intervals (CIs)=1.06-1.41]. Specifically, a stratified analysis showed that excess body weight was associated with an increased risk of cardia gastric cancer [overweight and obese (BMI 25), OR=1.55, 95% CIs=1.31-1.84] and gastric cancer among non-Asians (overweight and obese, OR=1.24, 95% CIs=1.14-1.36); however, the stratified analysis also showed that there was no statistically significant link between excess body weight and gastric cancer in the following subgroups: males (overweight and obese, OR=1.22, 95% CIs=0.96-1.55), females (overweight and obese, OR=1.13, 95% CIs=0.65-1.94), non-cardia gastric cancer (overweight and obese, OR=1.18, 95% CIs=0.96-1.45) and Asians (overweight and obese, OR=1.17, 95% CIs=0.88-1.56). The combined results of this meta-analysis, however, do indicate that overweight and obesity are associated with an increased risk of gastric cancer. The strength of the association also increases with increasing BMI.

Endogenous estrogen exposure in relation to distribution of histological type and estrogen receptors in gastric adenocarcinoma

BACKGROUND

Estrogen might protect women against gastric adenocarcinoma of the intestinal histological type. We addressed this hypothesis and proposed that gastric estrogen receptors (ERs) are involved.

METHODS

A population-based cohort of patients with gastric adenocarcinoma diagnosed in 1958-2004 in the county of Stockholm was identified through the Swedish Cancer Register. The patients were categorized regarding their endogenous estrogen exposure at diagnosis into: women aged less than 50 years, labelled "exposed women" (n=364), men aged less than 50 years, labelled "unexposed men" (n=396), and women aged more than 70 years, labelled "unexposed women" (n=3008). Tumor specimens were reviewed, and 289 cases were classified into intestinal (n=101) or diffuse type (n=188). Cases of intestinal adenocarcinomas (n=45) were tested for presence of ERalpha, ERbeta, and ERbeta cx by immunohistochemistry.

RESULTS

Compared to "exposed women", the intestinal type of gastric adenocarcinoma was more than four times more common among "unexposed men" (odds ratio [OR], 4.7; 95% confidence interval [CI], 2.2-10.3) and nine times more common among "unexposed women" (OR, 9.1; 95% CI, 4.3-19.6). No differences in ER expression were found. A comparison of ERs in tissues taken from the tumors and adjacent gastric mucosa revealed a loss of ERbeta and a gain of ERalpha in the tumor cells. The presence of ERbeta cx was identified for the first time in gastric tumors.

CONCLUSION

Gastric adenocarcinoma of the intestinal type is less common in women with high endogenous estrogen exposure, indicating a preventive effect of estrogen. No differences in the distribution of ERs was found between the three estrogen exposure groups. The presence of ERbeta cx in gastric cancer warrants further investigation.

Polymorphisms in estrogen- and androgen-metabolizing genes and the risk of gastric cancer

Androgens and estrogens may play a role in gastric cancer etiology. To investigate the association of gastric cancer with single-nucleotide polymorphisms (SNPs) in six genes (COMT, CYP1B1, CYP17A1, CYP19A1, HSD17B1 and SHBG) involved in estrogen and androgen synthesis and metabolism, 58 haplotype-tagging SNPs were genotyped in 295 gastric cancer cases and 415 controls from a population-based study in Poland. We assessed differences in haplotype frequency between cases and controls using a global score test and calculated multivariate odds ratios (ORs) and 95% confidence intervals (CIs) for individual haplotypes using logistic regression. We found associations in one linkage disequilibrium (LD) block containing the 3' untranslated region of COMT (rs9332377, rs165728, rs165849 and rs1110478), global score test (df = 4, P = 0.033). Relative to the most frequent GATA haplotype, the GATG haplotype was associated with statistically significant increased gastric cancer risk (OR = 1.50, 95% CI: 1.06-2.12; false discovery rate (FDR) value = 0.459) and the AACA haplotype with borderline increased risk (OR = 1.36, 95% CI = 1.00-1.85; FDR = 0.50). We also found associations for the LD block containing part of the SHBG coding region (rs6258, rs6259, rs2955617, rs1641544 and rs1641537). The CACCC haplotype was associated with statistically significant lower gastric cancer risk relative to the referent CGACC haplotype (OR = 0.55, 95% CI = 0.34-0.90; FDR = 0.459), but the overall score test was statistically non-significant. No other statistically significant associations were observed. In summary, we found possible associations between gastric cancer and polymorphisms in COMT, involved in estrogen inactivation, and SHBG, a modulator of hormone bioavailability. These findings should be interpreted cautiously until replicated in other studies.

Oestrogen and the enigmatic male predominance of gastric cancer

Gastric cancer is the second most common cause of cancer death worldwide, and annually it causes over 150,000 deaths in Europe and 700,000 deaths globally. The incidence of gastric cancer shows an enigmatic male dominance with a male-to-female ratio of about 2:1. This sex ratio cannot be entirely attributed to the differences in the prevalence of known risk factors between the sexes. This review focuses on the potential role of oestrogen in explaining the male predominance in gastric cancer. Some data argue in favour of sex hormonal influence. Women with a longer fertility life and those on hormone replacement therapy seem to have a decreased risk of gastric cancer, and men who have been treated with oestrogen for prostate cancer have a decreased risk. Use of tamoxifen in women seems to increase their risk of gastric cancer. Animal studies indicate that oestrogen may offer protection against the development of this cancer as for example ovariectomised mice are at an increased risk, whilst administration of female sex hormones decreases the incidence of gastric cancer. Oestrogen may exert its effect by acting on oestrogen receptors (ERs). Both ERalpha, ERbeta and the latest discovered ERbetacx have been identified in gastric tissue. The biological means behind this is not yet clear but various mechanisms have been suggested. There are indications that oestrogen may lead to an increased expression of trefoil factor proteins, which protect mucous epithelia or inhibit the expression of c-erb-2 oncogene.

Family history of cancer and stomach cancer risk

A family history of stomach cancer in first-degree relatives increases the risk of stomach cancer, but uncertainties remain as concerns the variation of the risk according to age, sex and type of relative, as well as on the role of family history of other cancers. We investigated the issue using data from a multicentric case-control study conducted in Italy between 1997 and 2007 on 230 cases aged not more than 80 years, with histologically confirmed incident gastric cancer and 547 controls admitted to hospital for acute, non neoplastic conditions. Logistic regression models adjusted for the effect of sex, age, year of interview, education, body mass index (BMI), tobacco smoking and number of brothers and sisters were used to estimate the odds ratios (OR) of stomach cancer. Relative to subjects with no history, those with a family history of gastric cancer had an OR of 2.5 (95% confidence interval (CI) 1.5-4.2). No significant heterogeneity emerged according to sex or age of the proband or of the affected relative, or smoking habits, BMI and education of the proband. As suggested from previous studies the OR was higher when the affected relative was a sibling (OR=5.1, 95% CI: 1.3-20.6) rather than a parent (OR=2.2, 95% CI: 1.2-3.9), although the heterogeneity test was not significant. The risk of stomach cancer was not increased in subjects with a family history of cancer at any other site. The OR for all sites excluding stomach was 1.0 (95% CI: 0.7-1.4).

Parity and risk of stomach cancer by sub-site: a national Swedish study

We investigated stomach cancer risk by anatomic sub-site in relation to parity, as a marker for higher exposure to sex hormones, in a case-control study, nested within a cohort of 2,406,439 Swedish women born in 1925 or later and followed from 1970 or age 30 until emigration, death, any cancer diagnosis, or through 2004, whichever occurred first. We identified 286 cardia and 2498 non-cardia stomach cancer cases with five matched controls for each case. Cross-linkage with the Multi-Generation Register provided information about reproductive history. Using conditional logistic regression models for estimating odds ratios (ORs) and corresponding 95% confidence intervals (CIs), adjusted for education level and occupation, we found no association between any aspect of parity and non-cardia stomach cancer (OR=1.01, 95% CI 0.89-1.15, comparing parous with nulliparous women). However, a 30% risk reduction for postmenopausal cardia cancer (OR=0.7, 95% CI 0.4-1.0) was noted among parous relative to nulliparous women and the risk for premenopausal cardia cancer fell with increasing number of children (P for trend=0.04). Our results indicate that exposure to female sex hormones does not protect against non-cardia stomach cancer and does not explain male predominance. The observed moderate inverse relationship between parity and cardia cancer may be mediated by non-hormonal factors and warrants further study.

Inhibitory effect of nordihydroguaiaretic acid, a plant lignan, on Helicobacter pylori-associated gastric carcinogenesis in Mongolian gerbils

Recent epidemiological studies have demonstrated that consumption of certain natural products can lower cancer risk in humans. For example, plant-derived lignans have been shown to exert chemopreventive effects against cancer in vitro and in vivo. In the present study, the effects of three such lignans, termed arctiin, arctigenin, and nordihydroguaiaretic acid (NDGA), on the proliferation of Helicobacter pylori and the prevention of H. pylori-associated gastric cancer were investigated in Mongolian gerbils. To examine the effects of arctigenin and NDGA on stomach carcinogenesis, specific pathogen-free male, 5-week-old gerbils were infected with H. pylori, administered 10 p.p.m. N-methyl-N-nitrosourea in their drinking water and fed diets containing various concentrations of lignans until they were killed after 52 weeks. At a dietary level of 0.25%, NDGA significantly decreased the incidence of gastric adenocarcinomas. Arctigenin, in contrast, failed to attenuate neoplasia at a level of 0.1%. Both NDGA and arctigenin significantly reduced serum 8-hydroxy-2'-deoxyguanosine levels at doses of 0.25 and 0.05% (NDGA), and 0.1% (arctigenin). Administration of 0.25% NDGA significantly suppressed the formation of intestinal metaplasia both in the antrum and the corpus. Although all three lignans dose-dependently inhibited the in vitro proliferation of H. pylori, there were no differences in the titers of anti-H. pylori antibodies or the amount of the H. pylori-specific urease A gene among all H. pylori-infected groups. These results suggest that NDGA might be effective for prevention of gastric carcinogenesis. The possible mechanisms appear to be related to inhibitory effects on progression of gastritis and antioxidative activity rather than direct antimicrobial influence.

Prospective cohort study of body mass index in adolescence and death from stomach cancer in Japan

We investigated the association between body mass index (BMI) values and the risk of death from stomach cancer later in life. From 1992 to 2000, 28 443 participants (13 211 men and 15 232 women) were followed, and 129 deaths from stomach cancer (86 men and 43 women) occurred. BMI (BMI at the baseline) and BMI(20y) (BMI at age 20 years) were obtained by questionnaire at the beginning of the study. Men in the middle and highest tertiles of BMI(20y) had a higher risk of death from stomach cancer than those in the lowest tertile (after controlling for covariates, hazard ratio [HR] = 2.73 with 95% confidence interval [CI] 1.26-5.89 for the middle tertile; HR = 2.15 with 95% CI 0.97-4.73 for the highest tertile), although there was no significant trend (P = 0.30). Likewise, women in the middle and highest tertiles of BMI(20y) had an increased risk of death from stomach cancer (HR = 5.17 with 95% CI 1.50-17.87 for the middle tertile; HR = 4.22 with 95% CI 1.18-15.05 for the highest tertile; P for trend = 0.05). The analysis of BMI at the baseline did not show a significant relationship with the risk of death from stomach cancer. These results suggest that a high BMI(20y) is associated with an increased risk of death from stomach cancer.

Fruit and vegetable consumption and gastric cancer by location and histological type: case-control and meta-analysis

The available information favours a greater impact of environmental exposures on intestinal type gastric cancer, and risk factors for the cardia and distal stomach cancers also appear to be different. We aimed to estimate the association between fruit and vegetable intake and gastric cancer, by location and histological type. We performed a population-based case-control study and a meta-analysis of studies addressing this issue. Incident cases (n=305) were identified in two large teaching hospitals (Porto, Portugal), and controls were randomly sampled among city dwellers (n=1129). Published studies were searched through PubMed, and effects were combined with random effects meta-analysis. In our case-control study, the odds ratio (OR) for the comparison of the highest vs. lowest tertile of fruit consumption was 0.47 [95% confidence interval (CI): 0.21-1.05] for cardia, 0.53 (95% CI: 0.35-0.80) for non-cardia cancer, 0.36 (95% CI: 0.20-0.62) for intestinal, and 1.00 (95% CI: 0.53-1.90) for the diffuse histological type. For vegetables, the corresponding OR was 0.59 (95% CI: 0.26-1.35), 0.85 (95% CI: 0.58-1.26), 0.95 (95% CI: 0.57-1.57), and 0.60 (95% CI: 0.32-1.14). In meta-analysis, considering fruit consumption (highest vs. lowest category), the combined OR was 0.58 (95% CI: 0.38-0.89) for cardia, 0.61 (95% CI: 0.44-0.84) for non-cardia, 0.49 (95% CI: 0.33-0.72) for intestinal type, and 0.82 (95% CI: 0.57-1.20) for diffuse type. Vegetables also decreased the risk of cardia (OR=0.63, 95% CI: 0.50-0.79), non-cardia (OR=0.75, 95% CI: 0.59-0.95), intestinal (OR=0.61, 95% CI: 0.44-0.86), and diffuse type (OR=0.67, 95% CI: 0.44-1.01). Fruit or vegetable intake was associated with a decreased risk of gastric cancer regardless of the anatomical location and the histological type, although dietary intake had a more clear-cut protective effect on intestinal type cancers.

Risk for gastric cancer after cholecystectomy

BACKGROUND

It is becoming increasingly evident that chronic inflammation may predispose cancer development. In the stomach, inflammation caused by Helicobacter pylori infection is linked to gastric cancer. Cholecystectomy is regularly followed by duodenogastric bile reflux and reactive gastritis. To test whether a noninfectious long-standing inflammation impels gastric carcinogenesis as well, we assessed the risk of gastric cancer in a large, population-based cohort of cholecystectomized patients.

METHODS

We identified 251,672 individuals, in the Swedish National Inpatient Register, who had undergone cholecystectomy between 1970 and 1997. All incident cases of gastric cancer were identified through linkage to the Swedish Cancer Registry. Standardized incidence ratios (SIRs) were calculated for comparisons with cancer rates of the general population in Sweden.

RESULTS

We found an 11% greater overall risk of distal gastric cancer (SIR=1.11, 95% CI 1.04-1.19). The risk increase was only observed among men (SIR=1.21, 95% CI 1.10-1.32), whereas no excess risk was evident for women. For men, the risk was elevated for up to 10 yr after surgery, but this elevation disappeared with longer follow-up time. There was no clear association between cholecystectomy and cardia cancer (SIR=0.95, 95% CI 0.76-1.16).

CONCLUSIONS

Inconsistency over gender strata, implausibly short induction and latency time, and disappearance of the effect over time makes a causal relationship between cholecystectomy and distal gastric cancer less likely. The findings set aside concerns of harmful long-term consequences of cholecystectomy.

Tobacco smoking and gastric cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population

BACKGROUND

We evaluated the association between tobacco smoking and gastric cancer risk among the Japanese population based on a systematic review of epidemiologic evidence.

METHODS

Original data were collected by searches of MEDLINE using PubMed, complemented with manual searches. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility, as evaluated previously by the International Agency for Research on Cancer.

RESULTS

Ten cohort studies and 16 case-control studies were identified. In men, most studies reported moderate or strong positive associations between smoking and gastric cancer. In women, the positive association was weaker than in men. Of eight studies (three cohort studies and five case-case control studies), two cohort and three case control studies reported a weakly to strongly increased risk of gastric cancer. The summary relative risk for current smokers was estimated to be 1.56 (95% confidence intervals 1.36-1.80), 1.79 (1.51-2.12), 1.22 (1.07-1.38) for the total population, men and women, respectively.

CONCLUSION

We conclude that there is convincing evidence that tobacco smoking moderately increases the risk of gastric cancer among the Japanese population.

Risk factors of gastric cancer specific for tumor location and histology in Cali, Colombia

AIM: To examine histology- and tumor-location specific risk factors of gastric cancer (GC).

METHODS: This was a case-control study. The study subjects were 216 GC patients newly diagnosed during the period 2000-2002 and 431 controls selected from non-cancer patients matching in age, gender, and hospital. We obtained information on lifestyles, dietary habits, and others by a questionnaire.

RESULTS: The subjects who were not eldest among his/her siblings were at a slightly elevated GC risk (OR 1.3; 95% CI 0.8-2.0). Salting meals before tasting was related to an increased GC risk (OR 3.5; 95% CI 1.6- 7.3). Frequent consumptions of fruits (OR 0.3; 95% CI 0.1-1.0) and vegetables (OR 0.3; 95% CI 0.1-1.0) were related to decreased GC risks. On the other hand, frying foods (OR 1.9; 95% CI 1.0-3.6) and cooking with coal (OR 1.8; 95% CI 1.3-2.6) were related to increased GC risks. Neither Lauren’s histological classification (intestinal and diffuse types) nor tumor location significantly affected those associations except birth order. The subjects who were not eldest among his/her siblings had an increased risk of GCs in the distal and middle thirds, and their ORs were 1.7 (95% CI 1.0-2.8) and 1.9 (95% CI 0.8-4.3), respectively. The corresponding OR in the upper third stomach was 0.3 (95% CI 0.1-0.9). The differences of those three ORs were statistically significant (P = 0.010).

CONCLUSION: The present study shows that birth order, salt intake, consumption of fruits and vegetables, the type of cooking, and cigarette smoking are related to GC risk. In histology and tumor-location specific analyses, non-eldest person among their siblings is related to an increased GC risk in the distal and middle thirds of the stomach, and is related to a decreased GC risk in the cardia.

Tamoxifen exposure and risk of oesophageal and gastric adenocarcinoma: a population-based cohort study of breast cancer patients in Sweden

In a population-based cohort study of all women aged over 50 years with breast cancer in the Swedish Cancer Register in 1961–2003, those diagnosed before 31 December 1987 were regarded as unexposed to tamoxifen, whereas those diagnosed after that date were considered potentially exposed. Crosslinkages within the Cancer Register and the Registers of Death and Emigration enabled follow-up. Standardised incidence ratios (SIRs) of oesophageal and gastric cancer represented relative risks. Among 138 885 cohort members contributing with 1 075 724 person-years of follow-up, we found a nonsignificantly increased risk of oesophageal adenocarcinoma during the potential tamoxifen exposure period (SIR 1.60, 95% confidence interval (CI) 0.83–3.08), but the risk estimates decreased with increasing latency interval. No association was observed during the unexposed period. No increased risk of cardia adenocarcinoma was identified in either period. The risk of non-cardia gastric adenocarcinoma was increased in the potential tamoxifen period (SIR 1.27, 1.03–1.57), and almost doubled (SIR 1.86, 95% CI 1.10–3.14) in the period of longest latency (10–14 years). The corresponding overall SIR was increased in the unexposed group also, but here SIR did not increase with longer latency intervals. An increased risk of tobacco-related tumours, that is, oesophageal squamous-cell carcinoma and lung cancer, was limited to the unexposed cohort, indicating that confounding by smoking might explain the increased SIR during the unexposed period. We concluded that there might be a link between tamoxifen and risk of non-cardia gastric adenocarcinoma.

Body size and composition and the risk of gastric and oesophageal adenocarcinoma

Although evidence has been mounting that obesity may be related to the increased incidence of oesophageal and gastric cardia malignancies, these reports (mainly case-control studies) have relied on imperfect measures of obesity such as body mass index (BMI), and generally have not clearly distinguished between anatomical subsites within the oesophagus and stomach. In a prospective study of people aged 27-75 years, we directly measured fat mass and fat-free mass (using bioelectrical impedance analysis), height, weight and waist and hip circumferences. Among 41,295 people followed on average for 11.3 years, 30 cases with cancers in the gastric cardia or lower third of the oesophagus and 68 cases with noncardia gastric adenocarcinomas were ascertained via the population cancer registry. The risk of adenocarcinoma of the lower oesophagus and gastric cardia was positively associated with BMI with a hazards ratio (HR) and (95% confidence interval) for people with BMI>or=30 kg/m2 compared with those<25 kg/m2, of 3.7 (1.1-12.4), an HR per 10 cm increase in waist circumference of 1.46 (1.05-2.04), and a HR per 10 kg increase on fat-free mass of 2.06 (1.15-3.69). Noncardia gastric adenocarcinoma showed little relationship with body size. We observed an increased risk of adenocarcinoma of the lower oesophagus and gastric cardia associated with increased BMI, central adiposity and the nonfat component of weight, but found no association with noncardia gastric adenocarcinoma. An increasing prevalence of obesity may be associated with the increasing incidence of gastro-oesophageal cancer observed in many populations.

Hormone replacement therapy and risks of oesophageal and gastric adenocarcinomas

Oesophageal and gastric adenocarcinoma share an unexplained male predominance, which would be explained by the hypothesis that oestrogens are protective in this respect. We carried out a nested case–control study of hormone replacement therapy (HRT) among 299 women with oesophageal cancer, 313 with gastric cancer, and 3191 randomly selected control women, frequency matched by age and calendar year in the General Practitioners Research Database in the United Kingdom. Data were adjusted for age, calendar year, tobacco smoking, alcohol consumption, body mass index, hysterectomy, and upper gastrointestinal disorders. Among 1 619 563 person-years of follow-up, more than 50% reduced risk of gastric adenocarcinoma was found among users of HRT compared to nonusers (odds ratio (OR), 0.48, 95% confidence interval (CI) 0.29–0.79). This inverse association appeared to be stronger for gastric noncardia (OR 0.34, 95% CI 0.14–0.78) and weaker for gastric cardia tumours (OR 0.68, 95% CI 0.23–2.01). There was no association between HRT and oesophageal adenocarcinoma (OR 1.17, 95% CI 0.41–3.32).

Gastric cancer: global pattern of the disease and an overview of environmental risk factors

This first part of this chapter looks at the worldwide burden of gastric cancer at the beginning of the 21st century and summarises available population-based routine data that describes the variation in incidence of the disease in relation to age, sex, geography and time period. Consideration is also given to the differences in the descriptive epidemiology of gastric cancer arising in the proximal cardia region of the stomach. In the second part of the chapter, a brief review of the main identified environmental risk factors is conducted drawing, where available, on published systematic literature overviews and meta-analyses. Evidence relating the aetiology of gastric cancer to Helicobacter pylori infection, dietary factors, smoking, occupation, physical activity and anthropometry is presented.

Estrogen and Risk of Gastric Cancer: A Protective Effect in a Nationwide Cohort Study of Patients with Prostate Cancer in Sweden

Background: The global pattern of male predominance in gastric cancer incidence remains unexplained. We tested the hypothesis that estrogen prevents gastric cancer in a cohort of men heavily exposed to estrogen.

Methods: We conducted a nationwide cohort study of men with a diagnosis of prostate cancer recorded in the Swedish Cancer Register in 1961-2000. Because estrogen therapy was the treatment of choice for prostate cancer in Sweden between 1950 and 1980, cohort members diagnosed earlier than 1980 were considered exposed to estrogen. Standardized incidence ratios (SIR) estimated relative risk. Complete follow-up was achieved through cross-linkages within the cancer register and the Swedish nationwide registers of emigration and causes of death.

Results: In 515,961 person-years of follow-up, we observed 304 gastric cancers as compared with 349 expected for the cohort members in the predefined “exposed” period 1961-1980, rendering a 13% decreased risk (SIR, 0.87; 95% confidence interval (95% CI), 0.78-0.98). Among patients with a latency of ≥15 years after a prostate cancer diagnosis in 1961-1980, SIR was 0.57 (95% CI, 0.30-0.97), suggesting a dose-response relation. Similarly, reduced risks were found for cardia cancer and noncardia gastric cancer. No decreased risk was found for the cohort members in 1981-2000, when estrogen treatment was less common (SIR, 0.99; 95% CI, 0.89-1.11).

Conclusions: Our study indicates a reduced risk of gastric cancer in a male cohort exposed to estrogen. These results support the hypothesis that estrogen may prevent gastric cancer, but additional studies are warranted.

Cigarette smoking and the risk of gastric cancer: a pooled analysis of two prospective studies in Japan

To examine the association between cigarette smoking and the risk of gastric cancer, we conducted a pooled analysis of 2 population-based prospective cohort studies in rural northern Japan. Cohort 1 included 9,980 men (>or=40 years old) and Cohort 2 included 19,412 men (40-64 years old). The subjects completed a self-administered questionnaire on cigarette smoking and other health habits. We identified 228 cases of gastric cancer among Cohort 1 subjects (9 years of follow-up with 74,073 person-years) and 223 among Cohort 2 subjects (7 years of follow-up with 141,675 person-years). From each cohort, we computed the relative risk (RR) and 95% confidence interval (CI) of gastric cancer associated with smoking using a Cox regression analysis and pooled these estimates to obtain summary measures. The pooled multivariate RRs (95% CIs) for current smokers and past smokers compared to subjects who had never smoked were 1.84 (1.39-2.43) and 1.77 (1.29-2.43), respectively. The higher number of cigarettes smoked per day among current smokers was associated with a linear increase in risk (trend p < 0.05). The significant increase in risk for past smokers remained for up to 14 years after cessation. An increased risk was noted for cancer of the antrum but not for cardia or body lesions. The risk was increased for both differentiated and nondifferentiated histologic subtypes. Our findings support the hypothesis that cigarette smoking is a risk factor for gastric cancer.