Colorectal cancer and diet in an asian population—A case‐control study among Singapore Chinese

Abstract

A hospital-based case-control study of diet and colorectal cancer was conducted among Chinese in Singapore (who constitute 77% of the population). A total of 203 cases and 425 controls were included. A history of the usual dietary intake one year prior to interview was taken using a quantitative food frequency questionnaire. Daily intakes of nutrients and selected food items were computed and stratified by tertiles of the control range, to assess risk in low-, medium- and high-intake categories. Effects were adjusted in analysis for age, sex, Chinese dialect group and occupation. For cancers of colon and rectum combined, significant observations were a protective effect of high cruciferous vegetable intake (OR = 0.50, p less than 0.01) and a predisposing effect of a high meat/vegetable consumption ratio (OR = 1.77, p less than 0.05). Similar results were observed for colon cancer alone. For rectal cancer alone (only 71 cases), significant (p less than 0.05) protective effects were observed for high intakes of protein (OR = 0.61), fibre (OR = 0.46), beta-carotene (OR = 0.54), cruciferous vegetables (OR = 0.51) and total vegetables (OR = 0.51). When further assessed by multiple logistic regression, tests for trend and assessment of risk in the extreme highest and lowest quintiles of the control range, the factors consistently significant were cruciferous vegetable intake and the meat/vegetable ratio. A particularly high relative risk was also noted in association with low coffee consumption (OR = 1.59, with p less than 0.05 for trend). No consistent trends were noted for fat or fibre intakes. For non-dietary variables investigated, a history of cholecystectomy increased the risk of both cancers combined (OR = 3.43, p less than 0.05) and colon cancer alone (OR = 4.39, p less than 0.01). This study in an Asian population of countries of Southern and Eastern Asia newly undergoing industrialization and in which rapid economic change is reflected in changing cancer patterns, suggests that the protective effects of certain dietary constituents, notably the cruciferous vegetables, may be more important than the hitherto stressed carcinogenic potential of fat and protein.

Smoking, drinking and colorectal cancer in Hong Kong Chinese: A case‐control study

“…9 This may account for the null studies that were conducted earlier in the smoking epidemics during which the extent of cigarette exposure was not sufficient to demonstrate an association with colorectal cancer in the study population. 6,7 Second, the prevalence of cigarette smoking reached its peak in Hong Kong about 20 years earlier than it did in mainland China. 9 This may explain why, unlike the present study, a recent report conducted in mainland China on tobacco-related mortality failed to identify any association with colorectal cancer.…”

“…5 The relationship between cigarette smoking and colorectal cancer in Chinese had previously been reported in 3 case-control studies and 1 cohort study. Two of the case-control studies, one on Singapore Chinese and another on northern Chinese, 6,7 were conducted more than a decade ago, whereas the other 2 studies, a cohort study from Shanghai and a case-control study on adult deaths in Hong Kong,8,9 were reported in 1997 and 2001, respectively. In all 4 studies, no association could be found between cigarette smoking and colorectal cancer.…”

“…10 A prospective cohort study of middleaged Chinese men in Shanghai did not show a significant increase in colorectal cancer mortality among heavy drinkers compared with nondrinkers. 11 Of the 3 case-control studies on colorectal cancer risk in different Chinese populations, 6,7,12 only the 1 by Hu et al 7 from northern China showed the amount of annual alcohol consumption to be an important risk factor for colon cancer and male rectal cancer. Even though there have been numerous studies on the various aspects of alcohol exposure, the effect of drinking cessation on colorectal cancer risk is unknown.…”

Coffee consumption and risk of colorectal cancer: a meta-analysis of observational studies

“…Michels et al (36) reported separate RR from two large US cohorts in their study, the Nurses' Health Study (NHS) (36a) and the Health Professionals Follow-up Study (HPFS) (36b) ; we counted the report as two prospective studies. Finally, our meta-analysis included twenty-five case-control (11,15,20,26,(28)(29)(30)(31)(33)(34)(35)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51) and sixteen cohort studies (17,19,21-25,27,32,36a,36b,37,52-55) .…”

Coffee consumption and the risk of colorectal cancer: A prospective cohort study in Japan

“…6 Sixteen out of 20 case-control studies supported an inverse association between high coffee consumption and colorectal cancer risk. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] However, the results of those studies may have been affected by selection bias or recall bias due to retrospective assessment of coffee consumption and other lifestyles-related factors after diagnosis of cancer. In contrast, results from prospective cohort studies have been inconclusive.…”