Meal Frequency and Risk of Colorectal Cancer1
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[CANCER RESEARCH 52. 3589-3592. July 1, 1992] Meal Frequency and Risk of Colorectal Cancer1 Silvia Franceschi,2 Carlo La Vecchia, Ettore Bidoli, Eva Negri, and Renato Talamini Epidemiology Unit, Aviario Cancer Center, Via Pedemontana Occidentale, 33081 Avlano (PN), [S. F., E. B., R. T.]; Mario Negri Institute for Pharmacological Research, Via Eritrea 62, 20157 Milan fC. L. K, E. N.J, Italy; and Institute of Social and Preventive Medicine, University of Lausanne, Bugnon 17, 1005 Lausanne, Switzerland 1C. L. V.J ABSTRACT PATIENTS AND METHODS The relation between meal frequency and the risk of colorectal cancer The present data were derived from an ongoing case-control study was investigated in a case-control study conducted in North Italy on 889 of several neoplasms of the digestive tract based on a network of cases of colon cancer, 581 cases of rectal cancer, and 2475 controls teaching and general hospitals from Greater Milan area and Pordenone province, North Italy (8-12). Recruitment of cases of colorectal cancer admitted to hospital for acute, nonneoplastic, or digestive disorders. As compared to individuals who reported 2 or fewer meals per day, the started in January 1985. All the interviews were conducted in hospital mull¡variatecolon cancer odds ratios were 1.7 [95% confidence interval before December 1990 and approximately 2% of cases and 3% of (95% CI), 1.5-2.11 for 3, and 1.9 (95% CI, 1.1-3.3) for 4 meals or more. control subjects refused to be interviewed. Corresponding rectal cancer odds ratios were 1.4 (95% CI, 1.1-1.7) for The cases studied were subjects with histologically confirmed large 3, and 1.9 (95% CI, 1.1-3.5) for 4 meals or more. The direct trends in bowel cancer diagnosed within the 6 months preceding interview (me risk of colorectal cancer with frequency of eating were not substantially dian time between cancer diagnosis and interview, 25 days). Altogether, 889 patients with colon cancer and 581 with rectal cancer were inter modified by allowance for various dietary and nondietary potential con viewed. The median age was 61 years for colon cancer and 62 for rectal founding factors, including an approximate measure of total energy cancer. intake, and did not show significant effect modification across strata of The comparison group comprised 2475 patients with a median age age, sex, education, and other major risk covariates. A role of meal of 56 years. No individual matching was performed, but the catchment frequency in the etiology of colorectal cancer is biologically plausible, areas of cases and controls were strictly comparable, i.e., control sub since when a meal is eaten, the gallbladder contracts and releases bile jects would have been referred, if affected by large bowel cancer, to the acids. Thus, eating patterns can influence the enterohepatic circulation hospitals where cases were contacted. None of the control subjects had and, consequently, the exposure time of intestinal mucosa to bile acids. malignant tumors, digestive tract disorders, or any condition related to alcohol and tobacco consumption, or which might have resulted in long-term modification of diet. The main diagnostic categories were: INTRODUCTION trauma (40%); nontraumatic orthopedic disorders (19%); acute surgical conditions, including plastic surgery (17%); eye disorders (13%), and Differences in diet have been suggested to account for the other illnesses such as diseases of the ear, nose, skin, or teeth (12%). majority of the variation in rates of colorectal cancer among A standard questionnaire was used to obtain information on sociod- countries (1, 2). A large number of case-control studies and emographic factors, general characteristics, life-style habits, including prospective investigations have suggested that diets high in fat smoking, alcohol, and coffee, and related personal and family medical and/or meat (3) and low in vegetables and/or whole-grain history. Further, patients were asked about their consumption per week cereals (4) enhance the probability of developing colorectal of 40 foods and beverages (including major sources of starch, proteins, cancer. fat, vitamins, and fiber in the Italian diet) and frequency of daily meals before the onset of the disease which led to the current admission. The specific factor(s) involved in such consistent dietary Intake of any solid food, but not of low-caloric beverages such as coffee associations are still unknown and it is plausible, according to or tea only, was considered a meal, irrespective of serving size. the widely held hypothesis which attributes to bile acids a crucial Data Analysis and Control of Confounding Variables. OKs ' of cancer role in colorectal cancer causation, that not only the quantity of the colon and rectum, together with their 95% approximate CIs, and quality of food intake but also the eating pattern is impor according to daily meal frequency were computed by means of uncon tant. Indeed, the rhythm of the enterohepatic circulation is ditional multiple logistic regression equations with maximum likeli largely determined by the number of daily meals (5). Only three hood fitting (13, 14). Allowance was made, (a) for age, sex, and area of residence; (b) also for potential confounding variables (/.<•..education, epidemiológica! studies have so far shown a detailed analysis body mass index (kg/m2), approximate tertiles of total energy, and red of colorectal cancer risk according to frequency of meals (6-8). meat intake). Total energy intake was estimated approximately by Increases of approximately 50% in risk of cancer of the colon multiplying the frequency of consumption per week of the 40 available in individuals reporting a higher meal frequency have already foods and beverages (alcoholic beverages included) by their average been reported, that persisted after allowance for various co energy content in kcal. The total intake of red meat, an indicator of variates [e.g., total energy intake (6), combined food scores (8), level of intake of proteins and fat of animal origin, included the etc.]. consumption of beef and pork from all available sources (i.e., beef, In order to contribute to this issue, we have examined the liver, raw ham, boiled ham, salami, and sausage). relation of risk of cancer of the colon and rectum with daily frequency of meals in a case-control study conducted in the RESULTS Northern part of Italy. The distribution of cases of colorectal cancer and controls by Received 1/10/92; accepted 4/22/92. age, sex, education, area of residence, and approximate intake The costs of publication of this article were defrayed in part by the payment of total energy and red meat is shown in Table 1. Cases of of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. rectal cancer, but not colon cancer patients, reported fewer 1The work was supported by the framework of the Italian National Research years of education as compared to control subjects. Both cases Council (CNR) Applied Project Clinical Application of Oncological Research, and with the contribution of the Italian Association for Cancer Research and the of colon and rectal cancer consumed red meat significantly Italian League against Tumours, Milan. more frequently than the control group (Table 1). 2To whom requests for reprints should be addressed, at Epidemiology Unit, Aviano Cancer Center, Via Pedemontana Occidentale, 33081 Aviano (PN), Italy. 3The abbreviations used are: OR, odds ratio; CI, confidence interval. 3589 Downloaded from cancerres.aacrjournals.org on September 25, 2021. © 1992 American Association for Cancer Research. MEAL FREQUENCY AND COLORECTAL CANCER Table 1 Distribution of 889 cases of colon cancer, 581 of rectal cancer, and 2475 controls according to various characteristics, North Italy 1985-1990 Cancer Controls Colon Rectum Variable No. No. No. Age(yr)<4040-4950-5960-6970-74SexMalesFemalesEducation (yr)°<55-8£9Area ofresidenceMilanPordenoneTotal energyintake(kcal/day)<18001800-2399>2400431092373281724604291225452217661232853582464.812.326.736.919.351.748.313.761.424.9*86.213.832.140.327.720551522341203492321063701044561251932071813.49.526.240.320.760.139.918.363.817.978.521.533.235.631.227348674573223915918843411555578177669976586384711.019.630.129.69.764.335.713.862.923.471.828.230.934.934.2 Red meat intake (weekly frequency) <6 282 31.7 212 36.5 958 38.7 7-8 272 30.6 168 28.9 758 30.6 335 37.7* 201 34.6* 759 30.7 " The sum of strata does not add up to the total because of missing values. * As compared to control subjects, x!i > 9.21 ; p < 0.01. Table 2 Odds ratio of cancer of the colon and rectum by daily meal frequency. North Italy, 1985-1990 Cancer Odds ratio (95% confidence interval) Colon Rectum Daily meal no.<2ffrequency Colon, no.36419918Controls, no.170770161Model1°1"1.8(1.5-2.2)'2.2(1.3-3.9)Model2*1"1.7(1.5-2.1)1.9(1.1-3.3)Model1°1"1.5(1.2-1.8)2.2(1.2-3.9)Model2*1"1.4(1.1-1.7)1.9(1.1-3.5) 5433 325>4 20Rectum, X!, (trend) 45.9' 38.5' I6.0f 13.7/ " Multiple logistic regression estimates adjusted for age, sex, and area of residence. " Multiple logistic regression estimates adjusted for age, sex, education, area of residence, body mass index, approximate total energy, and red meat intake. ' The sum of strata does not add up to the total because of missing values. d Reference category. * 95% confidence interval. >P< 0.001. The role of eating pattern on both cancers of the colon and was a hint that the effect of frequent eating may be stronger in rectum is considered in Table 2. For colon cancer the multivar- women than men and in individuals with lowest weight than iate OR was 1.7 (95% CI, 1.5-2.1) for three and 1.9 (95% CI, heavier people.