Waterpipe Tobacco Smoking and Risk of Stomach Cancer: A Case-Control Study in Vietnamese Men

OBJECTIVE

This study investigated the impacts of waterpipe tobacco (WTP) and cigarette smoking on stomach cancer development in Vietnamese men.

METHODS

A total of 80 stomach cancer cases and 146 controls were recruited in a hospital-based case-control study. Data on sociodemographic, anthropometric characteristics, tobacco smoking, and the dietary pattern was obtained based on a semi-quantitative food frequency and demographic lifestyle questionnaire; and venous anti-Helicobacter pylori IgG antibodies were tested by ELISA. Unconditional logistic regression analysis with adjustments for potential confounding was performed to estimate the association between target exposures and stomach cancer.

RESULTS

Compared to the never tobacco smokers, the risk of stomach cancer significantly increased among tobacco smokers (OR 2.95, 95%CI 1.26-6.90, p=0.013). Those who early started tobacco smoking before 26 years old had a high risk of SC (OR 3.04, 95%CI 1.29-7.20, p for trend=0.011). For types of tobacco, It was increased risk in exclusively cigarette smokers (OR 2.85, 95%CI 1.19-6.85, p=0.019) and in WPT smokers (OR 3.09, 95%CI 1.24-7.68, p=0.015). The daily frequency and longer duration of exclusively WPT or cigarette smoking tended to be significantly higher SC risk.

CONCLUSIONS

The findings suggest that tobacco smoking, particularly water pipe tobacco smoking, dramatically and independently increased the risk of stomach cancer.

Interaction of Helicobacter pylori Infection with Waterpipe Tobacco Smoking in the Development of Stomach Cancer in Vietnamese Men

OBJECTIVE

This study aims to examine the joint effect of H. pylori infection and tobacco smoking on the development of stomach cancer among Vietnamese men.

METHODS

A total of 80 stomach cancer cases and 146 controls were recruited in a case-control study conducted in a general hospital. Information on sociodemographic, anthropometric characteristics, tobacco smoking, and the dietary pattern was obtained based on a semi-quantitative food frequency and demographic lifestyle questionnaire; and venous anti-H. pylori IgG antibodies were tested by ELISA. Unconditional logistic regression analysis with adjustment for potential confounding was performed to estimate the association between target exposures and stomach cancer.

RESULTS

An increase in antibody level was related to an elevated odds of stomach cancer (Fifth versus bottom quintile, OR=3.07; 95%CI: 1.16, 8.12; p for trend = 0.032). Compared to participants who were negative with both H. pylori infection and tobacco smoking (either cigarette or waterpipe tobacco), individuals exposed to both these factors showed significantly greater odds of stomach cancer (OR=3.58. (95%CI: 1.32, 9.76, p=0.013). A similar combined impact of H. pylori infection and tobacco smoking was found in individuals who smoked a cigarette (excluded exclusive waterpipe tobacco smokers, ORs = 3.17; 95%CI: 1.13, 8.94, p=0.029) or waterpipe tobacco (excluded exclusive cigarette smokers; OR= 3.96, 95%CI: 1.28, 12.26, p=0.017).

CONCLUSIONS

The present study suggests an interaction between H. pylori infection and tobacco smoking, even waterpipe tobacco, to induce stomach cancer.

Trans-Lycopene and β-Cryptoxanthin Intake and Stomach Cancer in Vietnamese Men: A Pilot Case-Control Study

OBJECTIVE

To examine the association between dietary intake of Trans-Lycopene and β-Cryptoxanthin and stomach cancer in Vietnamese men.

METHODS

A case-control study including 80 male incident stomach cancer cases and 146 male controls was performed in a general hospital in Viet Nam. A validated semi-quantitative food frequency (SQFFQ) and demographic lifestyle questionnaire were designed, and venous blood samples were collected to determine H. pylori status by IgG ELISA. Nutrient intake was converted using the data of SQFFQ and the Nutritive Composition Table of Vietnamese Foods, updated in 2019. The respective associations between Trans-Lycopene and β-Cryptoxanthin intake and stomach cancer were examined using unconditional logistic regression analysis with adjustments for possible cofactors.

RESULTS

Both Trans-Lycopene and β-Cryptoxanthin intake and stomach cancer showed a significantly inverse association, tertile-3 versus tertile-1, (OR = 0.15, 95%CI: 0.06-0.35, p trend = 0.00) and (OR = 0.34, 95%CI: 0.14-0.79, p trend = 0.02, respectively). For Trans-Lycopene intake stratifying by H. pylori status remained the benefit effect against stomach cancer among H. pylori-negative participants (OR = 0.15, 95%CI: 0.03-0.69, p trend = 0.02) and H. pylori-positive participants (OR = 0.13, 95%CI: 0.04-0.42, p trend = 0.00).

CONCLUSIONS

Both Trans-Lycopene and β-Cryptoxanthin intake showed a strong protective effect against stomach cancer. The findings suggest that these two types of fat-soluble micronutrients would be considered as an anti-cancer therapy for both primary and secondary prevention.

Fruit and Vegetable Intake and Stomach Cancer among Male Adults: A Case-Control Study in Northern Viet Nam

OBJECTIVE

This study investigated the association between fruit and vegetable intake and stomach cancer, with considering the impacts of Helicobacter pylori (H. pylori) infection and tobacco smoking.

METHODS

A case-control study featuring 80 male incident stomach-cancer cases and 146 male controls was conducted in a general hospital in Viet Nam. A semi-quantitative food frequency and demographic lifestyle questionnaire were used; and venous blood samples were collected to determine H. pylori status by IgG ELISA. The respective associations between fruit and vegetable intake and stomach cancer were examined using unconditional logistic regression analysis with adjustments for possible cofactors.

RESULTS

Fruit intake and stomach cancer showed a weak inverse association when this became non-significant after adjusting for H. pylori infection (OR = 0.50, 95%CI: 0.22-1.12, p trend = 0.094). Stratifying by H. pylori status returned a negative trend for fruit intake and stomach cancer among H. pylori-negative participants (OR = 0.21, 95%CI: 0.06-0.69, p trend = 0.010), but no significant interaction for H. pylori-positive participants (OR = 0.76, 95%CI: 0.21-2.68, p trend = 0.670). Vegetable intake and stomach cancer showed no association, regardless of H. pylori status. Compared to ever-smokers with low intake, never-smokers with high vegetable (OR = 0.25, 95% CI: 0.06-0.95) and fruit intake (OR = 0.20, 95%CI: 0.06-0.65) showed the lowest odds of stomach cancer.

CONCLUSIONS

Fruit, but not vegetable, intake showed a weak inverse association with stomach cancer. H. pylori infection and tobacco-smoking status may influence the protective effects of fruit and vegetable intake on stomach cancer.
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Seasonality in mortality and its relationship to temperature among the older population in Hanoi, Vietnam

BACKGROUND

Several studies have established a relationship between temperature and mortality. In particular, older populations have been shown to be vulnerable to temperature effects. However, little information exists on the temperature-mortality relationship in Vietnam.

OBJECTIVES

This article aims to examine the monthly temperature-mortality relationship among older people in Hanoi, Vietnam, over the period between 2005 and 2010, and estimate seasonal patterns in mortality.

METHODS

We employed Generalized Additive Models, including smooth functions, to model the temperature-mortality relationships. A quasi-Poisson distribution was used to model overdispersion of death counts. Temporal trends, seasonality, and population size were adjusted for while estimating changes in monthly mortality over the study period. A cold month was defined as a month with a mean temperature below 19°C.

RESULTS

This study found that the high peak of mortality coincided with low temperatures in the month of February 2008, during which the mean temperature was the lowest in the whole study period. There was a significant relationship between mean monthly temperature and mortality among the older people (p<0.01). Overall, there was a significant decrease in the number of deaths in the year 2009 during the study period. There was a 21% increase in the number of deaths during the cold season compared to the warm season. The increase in mortality during the cold period was higher among females compared to males (female: IRR [incidence relative risk] =1.23; male: IRR=1.18).

CONCLUSIONS

Cold temperatures substantially increased mortality among the older population in Hanoi, Vietnam, and there were gender differences. Necessary preventive measures are required to mitigate temperature effects with greater attention to vulnerable groups.

Urinary 1-hydroxypyrene and 8-hydroxydeoxyguanosine levels among coke-oven workers for 2 consecutive days

OBJECTIVES

This study evaluated the levels of exposure to polycyclic aromatic hydrocarbons (PAHs) and their relationship with oxidative DNA damage among Vietnamese coke-oven workers.

METHODS

We collected urine from 36 coke-oven workers (exposed group) at the beginning and end of the shift on 2 consecutive days. We also collected urine from 78 medical staff (control group). Information was collected by questionnaire about smoking status, drinking habit, and working position. Urinary 1-hydroxypyrene (1-OHP) and 8-hydroxydeoxyguanosine (8-OH-dG) were measured using HPLC. All statistical analyses were performed with SPSS version 19.

RESULTS

Urinary 1-OHP was significantly higher in the coke-oven workers than in the control group (p<0.05). Top-oven workers had the highest levels of internal exposure to PAHs, followed by side-oven and then bottom-oven workers (5.41, 4.41 and 1.35 ng/mg creatinine, respectively, at the end of the shift on day 2). Urinary 8-OH-dG was significantly higher in top- and side-oven workers at the end of the shift on day 2 (4.63 and 5.88 ng/mg creatinine, respectively) than in the control group (3.85 ng/mg creatinine). Based on a multi-regression analysis, smoking status had a significant effect on urinary 8-OH-dG (p=0.049). Urinary 1-OHP tended to have a positive correlation with urinary 8-OH-dG (p=0.070).

CONCLUSIONS

Vietnamese coke-oven workers were exposed to PAHs during their work shift. Urinary 1-OHP exceeded the recommended limit, and elevated oxidative DNA damage occurred in top- and side-oven workers on the second day of work. A tendency for positive correlation was found between urinary 1-OHP and urinary 8-OH-dG.

Evaluation of the Vietnamese A6 mortality reporting system: injury as a cause of death

BACKGROUND

Despite the fact that the A6 mortality reporting system has been operating for almost 20 years in Vietnam, there has been no systematic evaluation of the system. This study assesses the completeness, sensitivity and positive predictive value of the system in relation to injury related mortality.

METHODS

Evaluation of the A6 system was undertaken in three (geographically distributed) provinces in Vietnam. Deaths identified in the A6 system were compared with deaths identified by an independent consensus panel to determine the per cent completeness of the A6 system. Verbal autopsies (VA) were conducted for all identified deaths from the consensus panels, and the sensitivity and positive predictive value of the A6 system were assessed using the VAs as the reference.

RESULTS

5273 deaths were identified from the A6 system with a further 340 cases identified by the independent consensus panel (total n=5613). Injury related deaths accounted for 13.6% (n=763) of all deaths with an overall injury mortality rate of 55.3 per 100 000 person years. The per cent completeness of the A6 system in relation to injury deaths was 93.9% with a sensitivity of 75.4%, specificity of 98.4% and positive predictive value of 88.4%.

CONCLUSIONS

The A6 mortality reporting system is embedded within the commune health system and is the lead mortality reporting system for the Ministry of Health. The system performs well in relation to its completeness and classification of injury related deaths. With further enhancements and ongoing support from government and donor agencies, the A6 system will be a valuable resource for identifying and planning preventive strategies targeting the leading causes of injury related deaths in Vietnam.

Cooking temperature, heat-generated carcinogens, and the risk of stomach and colorectal cancers

BACKGROUND

Food change due to cooking temperature and unrecognized heat-formed chemical carcinogens may impact on the risk of stomach and colo-rectal cancers. To test this hypothesis a case-control study was performed.

METHODS

A total of 670 cases of stomach and colo-rectal cancers matched with 672 hospital controls for sex and -/+5 years age admitted to three hospitals in Hanoi city in the North Viet Nam from October 2006 to September 2007 were the subjects. Five levels of food change due to cooking temperature were based on food color; white, pale yellow, yellow, dark yellow, and burnt. We asked study subjects to themselves report which of these five colors was their preferable intake before the onset of disease. The present study included; fried fishes-meats-eggs-potato-tofu; grilled foods; roasted foods; sugar, bread, heated wheat, and biscuits. These were cooked at temperatures as high as from 165 to 240 degrees C, based on the literature. Adjusted estimation of odds ratio was conducted controlling for possible confounding factors using STATA 8.0.

RESULTS

A high intake of roasted meats, bread and biscuit significantly increased the risk of cancer as much as OR= 1.63, 95%CI= 1.04-2.54; OR= 1.40, 95%CI= 1.03-1.90; OR= 1.60, 95%CI= 1.03-2.46 with probabilities for trend = 0.029, 0.035, and 0.037, respectively. For exposure among controls: 529 (79%) were not exposed at all to roasted meats; 449 (67%) were not exposed at all to bread; and 494 (74%) were not exposed at all to biscuit.

CONCLUSIONS

Observation of food change due to cooking temperature based on color is practically feasible for detecting associations with risk of developing cancer.

Development of a semi-quantitative food frequency questionnaire for dietary studies--focus on vitamin C intake

The present work aimed to provide a basis for examination of intake of selected food items determined with a semi-quantitative food frequency questionnaire (SQFFQ) and planned-food selection (PFS). From February to July of 2003, ninety one cancer patients and 90 matched (same sex and age within 5 years) non-cancer patients were directly interviewed by trained interviewers using the designed questionnaire at the inpatient-department of Viet Duc hospital, Ha Noi City, Viet Nam. Study subjects consumed more SQFFQ-food items than PFS-food items, so that the latter method might not accurately reflect dietary habits regarding estimation of nutrient intake, especially vitamins. Because these are beneficial factors acting against cancer development at many sites, the absence of food items selected by SQFFQ may result in a poor database regarding possible confounding factors. For futher clarification we then focused on vitamin C contributions of Vietnamese food and analyzed data of the National Nutritional Household Survey in 2000: 7,686 households throughout the country (vitamin C intake status) and 158 households with 741 persons of the population of Hanoi city (individual food items contributing to vitamin C). Direct interview using a validated questionnaire with an album of current Vietnamese food items-recipes and weighing checks was conducted to obtain information regarding all types of food intake over the last 24-hours. Contribution analysis using the Nutritive Composition Table of Vietnamese Foods, revision 2000, and stepwise regression analysis was applied. Average intake adjusted by ages of vitamin C per person per day was estimated. In total, the study subjects were found to currently consume 184 food items. Average intake of vitamin C was 72.5 mg per person per day at the national level: 57.9% from leafy vegetables, 33.4% from fresh fruits, and 6.4% from non-leafy vegetables. For vitamin C contribution, the highest 25 food items contributed to a cumulative 95.3% of vitamin C intake with a cumulative R2=0.99.

Gastric and colo-rectal cancer mortality in Viet Nam in the years 2005-2006

BACKGROUND

The International Collaborative Epidemiological Study of Host and Environmental Factors for Stomach and Colorectal Cancers in Southeast Asian Countries (SEACs) has been conducted in Viet Nam from 2003 to 2008 on a case-control basis. For further effective primary prevention, we examined gastric and colorectal cancer mortality nationwide in eight regions of Viet Nam in 2005-06.

METHODS

Both demographic data and lists of all deaths in 2005-06 were obtained from all 10,769 commune health stations in Viet Nam. Five indicators included name, age, sex, date of death and cause of death was collected for each case. We selected only communes having the list of deaths with clear cause for each case and crude mortality rate for all causes from 300-600/100,000 as published by the Ministry of Health for a reasonable accuracy and completeness. Obtained data for all causes, all cancers, stomach and colorectal cancer deaths as well as demographic information were processed using Excel software and exported to STATA 8.0 for estimation of world age-standardized cancer mortality rates per 100,000.

RESULTS

Data were available for 1,246 gastric cases, (819 male and 427 female) with age-standardized mortality rates from 12.7 to 31.3 per 100,000 in males and from 5.9 to 10.3 per 100,000 in females in the 8 regions of the country. For colorectal cancers, 542 cases (268 male and 274 female) gave mortality rates from 4.0 to 11.3 per 100,000 in males and from 3.0 to 7.8 per 100,000 in females.

DISCUSSION

Stomach cancer mortality in males in the region of North East in the North Viet Nam (2005-06) was higher than that in Japan (2002) (31.3 versus 28.7 per 100,000) while colorectal cancer in Viet Nam was lower. While prevalence of Helicobacter pyloris infection in Viet Nam was from 70-75% in both males and females, the stomach cancer rate in males was significantly higher than in females, 31.3 versus 6.8 per 100,000, suggesting an influence of other environmental risk factors. Whether protective factors are operating against colorectal cancer in Viet Nam now needs to be explored.

Population-based cancer survival in sites in Viet Nam

BACKGROUND

Very few population-based cancer survival studies have been performed in Viet Nam. The aim of the present study was to estimate observed and relative cancer survival rates in populations of Phu Tho, Hanoi and Hue city.

METHODS

A retrospective-cohort study was performed for all 12 districts of Phu Tho province (semi-highland area in the north), eight districts of Hanoi city (Capital) and four districts of Hue city in central area). Seven indicators were collected for each case of cancer death: name, age, sex, date of the first diagnosis having cancer, date of death, the cause of death and full address. Two steps were done. Firstly, we collected name, age, sex, date of death, the cause of death and full address; secondly, we collected date of the first diagnosis having cancer by a household visit by trained interviewer. Survival time was calculated from the date of death minus the date of diagnosis for each case of cancer. Observed survival rates for 1-year, 2-years, 3-years, 4-years and 5-years were estimated by the form of survival number multiplied by 100 then corrected for the registered number of cancer cases. For relative survival rates, the observed survival rates were corrected for the general population survival rate.

RESULTS

Males and females combined, for all cancer sites, 1-year, 2-year, 3-year, 4-year and 5-year observed and relative survival rates were 23.8%-23.9%, 8.5%-8.5%, 3.8%-3.8%, 2.6%-2.6%, 1.7%-1.7%, respectively. The highest one-year relative cancer survival rate was seen in the capital, Hanoi city (49,8%), followed by Hue city in the central area (24,7%), and the lowest in Phu Tho, north-semi-highland (21.8%).

CONCLUSIONS

The better cancer survival in Hanoi than in Phu Tho province, as well as the results overall, point to a need for greater efforts in early detection and treatment, especially in rural areas.

Cancer mortality pattern in Viet Nam

BACKGROUND

Health information in general and cancer information in particular in Viet Nam is an basic data for decisions related to health planning prevent against cancer. However, very limited database of cancer information bas been available to date. The aim of the present study was to examine cancer mortality pattern nationwide in Viet Nam.

METHODS

Descriptive cancer epidemiology was designed for the present study. Both demographic data and list of all deaths during the two years period, 2005-06, were obtained from all 10,769 commune health stations. Five indicators included name, age, sex, date of death and cause of death was collected for each case. A guideline to report demographic data of each commune and information of each case who has been lived at least 6 months in their commune was prepared in the designed form and sent by express mail service to all the heads of 10,769 commune health stations throughout country. The data comprises all cancer mortality records at the commune-level for the period 2005-06. All obtained data of cancer deaths as well as demographic information was computed using Excel software. The Excel data was exported to STATA 8.0 for cancer analysis. Cancer case was coded following ICD-10.

RESULTS

To date, 94.6% of the 10,769 communes (from the 638 of 671 districts within the 64 provinces) have forwarded the required data and we currently have approximately 93,719 cancer deaths for the 2 years period. Number of person-year was 76,726,873 in 2005 and 77,902,688 in 2006. Number of cancer deaths was 45,413 (29,189 males and 16,224 females) in 2005 and 48,306 (31,447 males and 16,859 females) in 2006. Male to female ratios were 1.8 and 1.9 in 2005 and 2006, respectively. Three most common cancer sites numbered of 61,079 (65% of all 93,719 cancer deaths) included 25,410 liver cancer; 22,209 lung cancer; and 13,460 stomach cancer. Among both males and females, liver cancer was ranked in the first most common (31,04% and 19.91%), followed by lung cancer (26.69% and 18.21%) and stomach (14.42% and 14.26%). Among females, cervix and other female genital cancers were ranked in the four most common (9.13%) and breast cancer was about 5.69%.

CONCLUSIONS

Participated proportion of nationwide administration units and population was over 90% to report about 93,719 deaths from cancer that suggested that cancer has been highly concerned by social as well as people due to a number of thousand life lost. This condition will accept well primary cancer prevention at commune level in Viet Nam to eliminate the ancient disease of cancer in human.

Development of population-based cancer mortality registration in the North of Viet Nam

BACKGROUND

Regional cancer distributions provide useful pointers to potential environmental risk factors. Cancer death registration data are also basic for checking completeness of population-based registration of cancer incidence. The aim of the present project was to develop population-based cancer mortality registration in various regions in the North of Viet Nam.

METHODS

Cancer data were accessed from the database of population-routine-based death registration performed by medical workers at commune health stations based on the guidelines of the Ministry of Health. All deaths occurring in the communities were registered and the registration process was monthly reviewed for each fatal case regarding the name, age, sex, address, occupation, date-place-cause of death, and information concerning to pre-death medical care during the study period from 1999 to 2005. The list of deaths and residents of the study population were carefully cross-checked with other information sources to avoid under or over registration. The study sites were Red River Delta areas and a high-mountain area. The world population structure was used to estimate age-standardized cancer mortality rates per 100,000 (ASR).

RESULTS

During 4,330,620 person-years estimated during 1999 to 2005, 21,108 deaths were registered. The crude death rate from all causes was 487.4/100,000. Among them, 4,244 cancers in all sites (2,835 in males and 1,409 in females) were registered, giving mortality rates/100,000 of 134.6 and 63.3 (crude), and 155.7 and 54.3 (ASR), for males and females, respectively. The rate for the high-mountain area was only half (45.5) those in the Red River Delta (95.2-117.4). Male to female ratios were ranked from 2.2 to 3.1. Cancer accounted for about 20% of all causes of death.

CONCLUSIONS

The present findings suggest that in Viet Nam, development of reliable population-based cancer mortality registration is feasible and practical.

Anti-smoking initiative and decline in incidence rates of lung cancer in Viet Nam

Viet Nam had the highest reported male smoking prevalence rate (72.8-74.3%) in the world in the 1990s. Production of tobacco products was about 0.44 kg or 600 cigarettes per capita per year in 1994 for domestic use. Population-attributable risk per cent of lung cancer due to smoking was about 69.7%. Males in the south have a lower reported smoking prevalence rate (OR=0.7) and a significant lower incidence rate of lung cancer, age-standardized-incidence-rate per 100,000 (ASR) 33.1 vs 24.6 when compared to males in the north. Incidence rates of lung cancer significantly declined in Hanoi (ASR 34.9-33.1 and 6.3-5.8) and Ho Chi Minh City (ASR 24.6-23.7 and 6.8-5.6) between 1991-1997 and at the national level between 1990-2000 (ASR 30.4-30.1 and 6.7-6.6) in males and females, respectively. This decline in incidence rate of lung cancer resulted from the great achievements of the National Tobacco Control Program over about a 10-year period from 1989 to help people stop smoking. The present finding should stimulate further primary cancer prevention efforts in developing countries, including Viet Nam. It also suggests that the method applied to translate scientific evidence of smoking harm to people and into health policy, is a useful tool to drive people's attitude to stop smoking and remove its human carcinogens from our society.

Cancer mortality in a Hanoi population, Viet Nam, 1996-2005

BACKGROUND

Hitherto, cancer mortality data have not been available in Viet Nam, so that the real public health problem with this disease has yet to be addressed and recognized in the country with a population of over 80 million in South East Asia. The aim of the present pilot study was to examine cancer mortality in a commune population of Hanoi city, 1996-2005.

METHODS

Cancer data was accessed from the database of the population-routine-based death registration performed by medical workers at commune health stations based on the guidelines of the Ministry of Health at Hanoi city. All deaths occurring in the community were registered. This registration process was monthly reviewed for each fatal case regarding the name, age, sex, address, occupation, date-place-cause of death, and information concerning to pre-death medical care during the study period from Jan. 1996 to Dec. 2005. The list of death and residents of the study population was carefully cross-checked with other information sources to avoid under- or over-registration. The world population structure was used to estimate age-standardized cancer mortality rates per 100,000, (ASR).

RESULTS

During 60,770 person-years estimated from Jan. 1996 to Dec. 2005, 320 deaths and their causes were registered. Among them, 100 cancer cases of all sites (66 males and 34 females) were included. Cancer mortality rates were 222 and 109 (Crude), 353 and 115 (ASR), for males and females, respectively. For both genders combined, lung cancer was the most common, 27 cases, followed by liver, 26 cases and stomach, with 19. Proportion of death from cancer was about 31% of all causes.

CONCLUSIONS

The present findings suggest that in Viet Nam, a developing country, cancer is indeed an important public health problem.

Pattern and Time Trends of Stomach Cancer in Asia from 1950-99

Background: As there is a lack of data on stomach cancer disease in Asia, the aim of the present study was to examine patterns and time trends for this neoplasm in Asian countries. Methods: A descriptive study was designed to examine the cancer pattern and time trend and to calculate the annual change in mortality and incidence of stomach cancer at 5-year intervals. Data were derived from the WHO Mortality Database, and Cancer Incidence in Five Continents. Results: The highest rates of stomach cancer mortality and incidence (ASR) were observed in Japan, followed by the Republic of Korea, and China, the lowest rates being observed in Thailand. The highest to lowest ratios were 50 and 32 for mortality and 120 and 45 for incidence in males and females, respectively. A decreased trend of mortality was found in all 16 countries where mortality data was available, however, before the decrease, an increased trend was found in Japan in the 1950s and in Sri-Lanka in the 1950-60s. In spite of a significant decrease in mortality nationwide in Japan, an increased trend of stomach cancer incidence was found in Hiroshima (ASR + 7.4 in males and + 1.5 in females for each 5-year period). Discussion: There are very large geographical differences in risk factors of stomach cancer from country to country, and these risk factors are still highly prevalent in specific areas of Asia. Further ecological study with emphasis on host and environmental factors for stomach cancer in Asian countries are strongly recommended.

Estimate of the Incidence of Hepatocellular Carcinoma Among Carriers of HBsAg (+) in the General Population of Hanoi, Viet Nam from 1991-93

Background: The estimated number of carriers of HBsAg (+) in the world significantly increased from 120 to 350 million from the 1970s to the 1990s. Eighty per cent of liver cancers are estimated to be due to chronic HBV infection. However, only limited data are available regarding liver cancer rates among carriers of HBsAg (+). The aim of the present study was to estimate the incidence of liver cancer among carriers of HBsAg (+) in the general population of Hanoi City, Viet Nam. Method: Data were derived from published reports for incidence of liver cancer (population-based cancer registry), the risk of HBV infection for liver cancer (case-control study), and the prevalence of HBV infection (stratified random sampling of the general population) in the same population of Hanoi City. The Method of Indirect Estimation in a Case Control Study was used in this study. Results: Crude incidence rates per 100,000 were 114 and 37 for carriers of HBsAg (+) in males and females, respectively. The age-standardized incidence rate per 100,000 among carriers of HBsAg (+) for liver cancer was 166 in males and 58 in females, (ASR, world population). The annual incidence of liver cancer among carriers of HBsAg (+) was strongly correlated with increased age in both males and females: the estimated value sharply increased from 6 to 655 per 100,000 for persons aged 0-9 and 50+, respectively, in males. Similarly, the estimated incidence of liver cancer also sharply increased from 8 to 233 per 100,000 for the age groups 10-19 and 50+, respectively, in females. Conclusion: The present results indicate a high age-dependent incidence of liver cancer among carriers of HBsAg (+) in a general population. These results for Hanoi City, Viet Nam point to the magnitude of the problem and provide a basis for intervention.

Work, salt intake and the development of stomach cancer

An excess of stomach cancer among workers has been observed and it could be argued that men whose occupation involves heavy work eat more and are consequently exposed to a greater quantity of carcinogens in their food. Working under conditions of heat stress greatly increases a worker's salt excretion by as much as 0.1-15.0 g through sweating during one shift of work. Workers exposed to heat stress had consumed daily as much as from 13.0 to 38.0 g of salt, which is much higher than the safe level of 6 g/person/day recommended by the WHO, to keep a balance of salt in the body. Because salt strongly enhances and promotes chemical gastric carcinogenesis and Helicobacter pylori infection in both humans and animals, there is an association between work, salt intake, and the development of stomach cancer among workers in particular and in humans in general.

Grand challenges in global health and the practical prevention program? Asian focus on cancer prevention in females of the developing world

In response to the request for 'Breakthrough Questions' for 'Grand Challenges in Global Health' recently published in Nature, the Asian Pacific Organization for Cancer Prevention should focus its attention on what projects are of the highest priority for integration with its Practical Prevention Program (PPP). The most common female cancers in most of the countries of Asia are carcinoma of the breast, followed by the uterine cervix. While the incidences of breast adenocarcinomas are still generally lower than in the Western world they are rapidly increasing, and squamous cell carcinomas of the cervix are a major problem. Clearly there are many areas which would reward research. One factor which appears of major relevance in the mammary gland case is the diet, and particularly the phytoestrogens included in 'tofu', along with physical exercise. The age at which these could be operating needs to be elucidated, with reference to timing of menarche and menopause, and also breast mammographic density, another predictor of likelihood of neoplasia. In the cervix, the predominant influence is well established to be persistent infection with a high risk 'oncogenic' type of human papilloma virus (HPV). Vaccines therefore hold much promise, but a better understanding of the mechanisms underlying spontaneous clearance of both infection and cervical intraepithelial neoplasia (CIN) of different grades is also essential for optimal intervention. The roles of smoking and antioxidant intake in particular deserve emphasis. In Asia, with the considerable variation evident in both breast and cervical cancer incidence rates, as well as in cultural and other environmental factors, we are in a very favourable position to meet two specific challenges: 1). elucidation of how diet in adolescence determines susceptibility to neoplasia of the mammary glands; and 2). determination of what governs persistence of HPV infection. Realisation of these pivotal research aims, with especial emphasis on the context of the PPP, is our shared goal.

Dietary factors and stomach cancer mortality

The present study examined the relationship between stomach cancer and the low intake of fresh fruit and vegetables and/or a high intake of pickled, preserved or salted foods and frequent use of cooking oil. During 139,390 person-year of follow-up of over 13,000 subjects, 116 died from stomach cancer. Using a Cox proportional hazards-regression analysis of relative risk (RR, 95% CI) controlling for age, sex, smoking and other dietary factors, a significant decline was found with a high consumption of green and yellow vegetables (RR=0.4, 95% CI=0.2-0.9). Reductions of between 40 and 50% were also observed with a high consumption of fresh foods (fruit, cuttle fish, tofu, and potatoes), but these associations were not statistically significant. The risk was significantly increased by the high consumption of processed meat (RR=2.7, 95% CI=1.0-7.4) and by the frequent use of cooking oil (RR=4.0, 95% CI=1.3-11.8). The high consumption of pickled food and traditional soups also increased risk, but not significantly. The findings suggest that a diet high in salt and low in vitamins may be associated with an increase in stomach cancer.

Estimates of cancer mortality in Hanoi and Ho Chi Minh City, Viet Nam in the 1990s

As cancer mortality data is not available, a study regarding the real problem of cancer mortality is timely and urgent in Viet Nam. Therefore the aim of the present study was to calculate cancer mortality in the city of Hanoi and Ho Chi Minh. The correlation between cancer mortality to incidence ratios and relative survival probabilities for 23 cancer sites was estimated according to SEER (1973-97), then cancer mortality was calculated from the cancer incidence and cancer survival for 25 cancer sites in each city. Cancer mortality rate for all cancer sites except skin (ASR per 100,000) was 103.9 for males and 52.4 for females in Hanoi, and 93.7 for males and 60.7 for females in Ho Chi Minh. For males, the five most common cancer deaths were cancers of the lung, liver, stomach, colon/rectum, and nasopharynx in both Hanoi and Ho Chi Minh. For females, cancer death in the cervix was uncommon in Hanoi but the most common site in Ho Chi Minh (ASR 2.2 VS. 14.2 per 100,000). The present findings are the first results of cancer mortality from Viet Nam and should be useful for further cancer control programs there.