Hospital outpatients are satisfactory for case-control studies on cancer and diet in China: a comparison of population versus hospital controls

Risk factors for the development of colorectal carcinoma: A case control study from South India

AIM: To study the association of colorectal carcinoma (CRC) with diet, smoking, alcohol, physical activity, body mass index, family history and diabetes.

METHODS: All consecutive patients with CRC confirmed by histopathology diagnosis were included. Age (± 5 years) and gender matched controls were selected among the patients admitted in surgery ward for various conditions without any co-existing malignancy. Food frequency questionnaire (FFQ) was developed and validated after pretesting by investigator trained in data collection techniques. Cases and controls were interviewed ensuring privacy, in similar interview setting, with same duration of time for both cases and controls without any leading question. Biological variables like family history of CRC in first degree relatives, history of diabetes mellitus; behavioral factors like tobacco use both smoking and smokeless form, alcohol consumption and physical activity were recorded. Dietary details were recorded using a FFQ consisting 29 food items with seven categories. Analysis was done using appropriate statistical methods.

RESULTS: Ninety-four histopathologically confirmed cases of CRC and equal number of age and gender matched controls treated over a period of two years were studied. Age distribution, mean age, male to female ratio, education level and socioeconomic status were similar in cases and controls. Intake of food items was categorized into tertile due to skewed distribution of subjects as per recommended cut off for consumption of food item. On univariate analysis red meat [OR = 7.4 (2.935-18.732)], egg [OR = 5.1 (2.26-11.36)], fish, fried food and oil consumption were found to be risk factors for CRC. On multivariate analysis red meat consumption of more than 2-3 times a month (OR = 5.4; 95%CI: 1.55-19.05) and egg consumption of more than 2-3 times a week (OR = 3.67; 95%CI: 1.23-9.35) were found to be independent risk factors for the development of CRC.

CONCLUSION: Egg and red meat consumption found to be independent risk factors for CRC. Smoking, alcohol, physical activity and family history were not associated with increased risk.

Dietary isoflavone intake is associated with a reduced risk of myelodysplastic syndromes

Isoflavones have been suggested to have protective effects on certain cancers. However, the association of soya foods or dietary isoflavones with the risk of myelodysplastic syndromes (MDS) has not been examined. Thus, the aim of this hospital-based case-control study undertaken in China in 2012-2013 was to investigate the association between dietary isoflavone intake and MDS risk. The analysis included 208 cases aged 19-85 years with MDS and 208 controls individually matched to the cases by sex, birth quinquennium and residential locality. Information on habitual food intakes, including nine items of soya foods, was sought from in-person interviews using a validated 107-item FFQ. Dietary intakes of daidzein, genistein, glycitein and total isoflavones were estimated using the 2008 US Department of Agriculture Isoflavone Database. OR were calculated from conditional logistic regression after adjustment for potential confounding by demographics, lifestyle and dietary factors. The mean daily intake of total isoflavones was 19·0 mg in cases and 23·0 mg in controls. Dietary intake of isoflavones was inversely associated with the risk of MDS. The adjusted OR in the highest tertile compared with the lowest tertile of intake were 0·43 (95 % CI 0·21, 0·85) for daidzein, 0·36 (95 % CI 0·18, 0·74) for genistein, 0·49 (95 % CI 0·25, 0·97) for glycitein and 0·40 (95 % CI 0·20, 0·81) for total isoflavones. The findings suggest that higher dietary intake of isoflavones is associated with a reduced risk of MDS in a Chinese population.

Green tea consumption and glutathione S-transferases genetic polymorphisms on the risk of adult leukemia

PURPOSE

Green tea may have a beneficial role of inhibiting leukemia. Glutathione S-transferases (GSTs) are known to detoxify certain carcinogens. We investigated the roles of green tea consumption and polymorphisms of GSTM1, GSTT1 and GSTP1 on the risk of adult leukemia, and to determine whether the associations varied within GSTs genotypes.

METHODS

A multicenter case-control study was conducted in China, 2008-2013. It comprised 442 incident, hematologically confirmed adult leukemia cases and 442 outpatient controls, individually matched to cases by gender, birth quinquennium and study site. Data were collected by face-to-face interview using a validated questionnaire. Genetic polymorphisms were assayed by PCR.

RESULTS

An inverse association between green tea consumption and adult leukemia risk was observed. Compared with non-tea drinkers, the adjusted odds ratios (95 % confidence intervals) were 0.50 (0.27-0.93), 0.31 (0.17-0.55) and 0.53 (0.29-0.99) for those who, respectively, consumed green tea >20 years, ≥2 cups daily and dried tea leaves >1000 g annually. In assessing the associations by GSTs genotypes, risk reduction associated with green tea consumption was stronger in individuals with the GSTT1-null genotype (OR 0.24; 95 % CI 0.11-0.53) than GSTT1-normal carriers (OR 0.67; 95 % CI 0.42-1.05; P interaction = 0.02). GSTM1 and GSTP1 did not significantly modify the inverse association of leukemia with green tea.

CONCLUSIONS

The results suggest that regular daily green tea consumption may reduce leukemia risk in Chinese adults regardless of GSTM1 and GSTP1 polymorphic status. The association between green tea and adult leukemia risk varied with GSTT1 genotype and highlights further study.

Diet and risk of adult leukemia: a multicenter case-control study in China

PURPOSE

Epidemiologic studies on diet and leukemia risk have shown inconsistent results. This study examined the associations between dietary factors and the risk of adult leukemia in Chinese populations.

METHODS

A multicenter case-control study was conducted in southeast and northeast China between 2008 and 2013. It included 442 incident cases with hematologically confirmed leukemia and 442 controls, individually match to cases by gender, birth quinquennium, and study site. Information on diet was sought from face-to-face interviews using a validated and reliable 103-item food frequency questionnaire. Odds ratios (ORs) and confidence intervals (CIs) were estimated by conditional logistic regression.

RESULTS

Vegetables intake was associated with decreased risk of adult leukemia, with a significant dose-response relationship and adjusted OR of 0.30 (95 % CI 0.18-0.50) for the highest versus the lowest quartiles intake. Compared with non-consumers, the adjusted OR was 0.51 (95 % CI 0.29-0.93) for those who consumed milk at the highest tertile. Intakes of fruits, red meat, poultry, and fish were not associated with the risk. Dietary nutrients, including dietary fiber, carotenoids, vitamins B1, B2, and C, niacin, and folate, were significantly associated with reduced risks. Elevated risk was related to dietary intake animal fat and dietary habits with frequent intakes of fat, deep-fried, and smoked foods ( p for trend <0.05).

CONCLUSIONS

Our findings suggest that diets rich in vegetables and adequate amount of milk reduce the risk of adult leukemia, whereas diets preferring fat, deep-fried, and smoked foods increase the risk in Chinese populations.