A prospective study of green tea consumption and cancer incidence, Hiroshima and Nagasaki (Japan)

Objectives: Laboratory and animal studies have shown a protective effect of green tea on cancer of different sites, but epidemiological evidence is limited and inconclusive. This prospective study in Japan examined the association between green tea consumption and cancer incidence. Methods: Subjects were 38,540 people (14,873 men, mean age 52.8 years; 23,667 women, mean age 56.8 years) who responded to a mail survey carried out between 1979 and 1981. A self-administered questionnaire ascertained consumption frequency of green tea using precoded answers (never, once per day, twice to four times per day, and five or more times per day). Follow-up continued until 31 December 1994. The study analyzed solid cancers (n = 3881); hematopoietic cancers (188); cancers of all sites combined (4069); and cancer of specific sites with more than 100 cases, i.e. stomach (901), colon (432), rectum (193), liver (418), gallbladder (122), pancreas (122), lung (436), breast (281), and bladder (122). Poisson regression was used to allow for city, gender, age, radiation exposure, smoking status, alcohol drinking, body-mass index, education level, and calendar time. Results: Green tea consumption was virtually unrelated to incidence of cancers under study. The relative risks of all cancers for those consuming green tea twice to four times per day and five or more times per day were 1.0 (95% confidence interval 0.91–1.1) and 0.98 (0.88–1.1), respectively, as compared with those consuming green tea once per day or less. Conclusion: Our findings do not provide evidence that regular green tea consumption is related to reduced cancer risks.     

Coffee and tea intake and risk of cancers of the colon and rectum: A study of 3,530 cases and 7,057 controls

The relationship between coffee, decaffeinated coffee and tea intake and risk of cancers of the colon and rectum was considered combining data from 2 case-control studies, one conducted between 1985 and 1991 in Northern Italy and the other between 1991 and 1996 in 6 Italian centers. Cases were patients below age 80, with histologically confirmed cancer of the colon (n = 2,166) or rectum (n = 1,364), and controls were 7,057 patients admitted to hospital for a wide spectrum of acute, non-neoplastic, non-digestive tract diseases. Compared with coffee non-drinkers, the risk of colon cancer was reduced in drinkers of 4 or more cups/day multivariate odds ratios (ORs) 0.73; 95% confidence intervals 0.60–0.89), with a significant trend in risk with dose; no significant association emerged between coffee drinking and risk of rectal cancer (OR 1.00 for drinkers of 4 or more cups/day). Decaffeinated coffee was consumed in small amounts by about 4% of cases and controls and the OR was 0.92 for colon and 0.88 for rectal cancers. Tea consumption was generally limited to 1 cup/day or to occasional intake and did not substantially modify the risk of colon and rectal cancers. No significant heterogeneity was found for the inverse relationship between coffee intake and colon cancer risk across strata of age at diagnosis, sex, smoking status, total alcohol and meat and vegetable intake, while the protection of coffee was stronger in people eating 3 or more meals/day. Thus, our results confirm that coffee intake has a quantifiable protective effect on colon cancer risk. Int. J. Cancer 73:193–197, 1997. © 1997 Wiley-Liss, Inc.     

Cigarette and alcohol consumption and the risk of colorectal cancer in Shanghai, China.

The relation of cigarette smoking and alcohol drinking to colorectal cancer risk has been inconsistent in the epidemiological literature. In a population-based case-control study of colorectal cancer in Shanghai, China, where the incidence rates are rising sharply, we examined the association with tobacco and alcohol use. Cases were aged 30-74 years and newly diagnosed with cancers of the colon (N = 931) or rectum (N = 874) between 1990 and 1992. Controls (N = 1552) were randomly selected among Shanghai residents, frequency-matched to cases by gender and age. Information on lifetime consumption of tobacco and alcohol, as well as demographic and other risk factors, was obtained through in-person interviews. Associations with cigarette smoking and alcohol use were estimated by odds ratios (ORs) and 95% confidence intervals (CIs). Among women, the prevalence of smoking and alcohol drinking was low, and no significant association with colon or rectal cancer was observed. Although cigarette smoking among men was not related overall to colon or rectal cancer risk, there was a 50% excess risk of rectal cancer (OR 1.5, 95% CI 0.9-2.5) among those who smoked 55 or more pack-years. Among men, former alcohol drinkers had an increased risk of colon cancer (OR 2.3, 95% CI 1.4-3.7) but not rectal cancer, while current drinkers had a 30-50% excess risk of colon cancer only among those with long-term (30+ years) and heavy (>560 g ethanol/week) consumption. The excess risks were mainly associated with hard liquor consumption, with no material difference in risk between proximal and distal colon cancer. Although cigarette smoking and alcohol drinking in general were not risk factors for colorectal cancers in Shanghai, there were small excess risks for rectal cancer among heavy smokers and colon cancer among heavy drinkers.     

Risk factors for colorectal cancer in a prospective study among U.S. white men

The association of diet, smoking/drinking and occupation with subsequent risk of fatal colorectal cancer was investigated in a cohort of 17,633 white males aged 35 and older, who completed a mail questionnaire in 1966. During the subsequent 20 years of follow-up, 120 colon cancer and 25 rectal cancer deaths were identified. Due to small numbers, no significant dose-response trends were observed in the study, but risk of colon cancer was elevated among heavy cigarette smokers (≥30/day; RR = 2.3, 95% CI 0.9–5.7), heavy beer drinkers (≥14 times/month; RR = 1.9, 95% CI 1.0–3.8) and white-collar workers (RR = 1.7, 95% CI 1.0–3.0) or crafts workers within service and trade industries (RR = 2.6, 95% CI 1.1–5.8). In addition, an increased risk was seen for those who consumed red meat more than twice a day (RR = 1.8, 95% CI 0.8–4.4). Risk patterns for cancers of the colon and rectum combined were similar to those reported for cancer of the colon, but the estimates were somewhat dampened. Our findings support previous reports that a high intake of red meat and a sedentary life-style may increase the risk of colon cancer. Int. J. Cancer77:549–553, 1998. Published 1998 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Food consumption and cancer of the colon and rectum in north-eastern Italy.

The relation between dietary factors and the risk of colorectal cancer was investigated in a case-control study conducted in Pordenone province, North-eastern Italy, on 123 cases of colon cancer, 125 of rectal cancer and 699 controls admitted to hospital for acute, non-neoplastic or digestive disorders. Consistent positive associations were observed with more frequent consumption of bread (odds ratio, OR = 2.1 for colon and 2.2 for rectum for highest vs. lowest tertile), polenta (OR = 2.1 for colon, 1.9 for rectum), cheese (OR = 1.7 for colon, 1.8 for rectum) and eggs (2.5 for colon, 1.9 for rectum), whereas reduced ORs were observed in subjects reporting more frequent consumption of tomatoes (OR = 0.5 for colon and 0.4 for rectum). High consumption of margarine exerted a significant protection against cancer of the colon whereas high consumption of carrot spinach, whole-grain bread and pasta (favorably) and red meat (unfavorably) affected rectal cancer risk in particular. Thus the present study gives support for a protective effect associated with a fiber-rich or vegetable-rich diet, while it indicates that frequent consumption of refined starchy foods, eggs and fat-rich foods such as cheese and red meat is a risk factor for colo-rectal cancer.     

Coffee consumption and digestive tract cancers

The relationship between coffee drinking and the risk of digestive tract neoplasms was analyzed in a case-control study of 50 cases of cancer of the mouth or pharynx, 209 of the esophagus, 397 of the stomach, 455 of the colon, 295 of the rectum, 151 of the liver, 214 of the pancreas, and 1944 control subjects admitted for acute, non-digestive tract disorders. There was no significant or consistent association between coffee and cancers of the mouth or pharynx, esophagus, stomach, liver, or pancreas. In particular, for pancreatic cancer, the multivariate relative risks for the intermediate and upper tertiles were 1.05 and 1.01, respectively. There were significant inverse trends in risk with measures of coffee consumption for colon and rectal cancers, the multivariate relative risks according to tertiles of coffee consumption being 0.86 and 0.64 for colon and 0.97 and 0.66 for rectum. This apparent protection is in agreement with some (but not all) previous epidemiological evidence and finds a possible biological interpretation in terms of interference on bile secretion, causing reduced bile acid and neutral sterol concentrations in the bowel. In conclusion, the results of this study, the major interest of which lies in the opportunity of drawing up an overall pattern of risk for various digestive neoplasms, offer further reassurance as regards the effects of coffee on digestive tract carcinogenesis.     

Coffee and tea consumption and cancers of the bladder, colon and rectum.

Coffee has been observed to be associated weakly or not at all with bladder cancer risk, inversely with colon cancer risk, and inconsistently with rectal cancer risk. The association between these cancers and consumption of coffee and tea was examined in a single case-control study conducted in Ontario, Canada from 1992 to 1994. A questionnaire was filled out by 927 bladder cancer cases, 991 colon cancer cases, 875 rectal cancer cases, and 2118 population controls. Although bladder cancer risk was not associated with coffee or tea, risk estimates associated with coffee among subjects who had never smoked were non-significantly increased. Colon cancer risk was inversely associated with coffee. Relative to those drinking less than 1 cup of coffee per day, the odds ratios (OR) for those drinking 1-2 cups was 0.9 (95% CI 0.8-1.1), for those drinking 3-4 cups was 0.8 (95% CI 0.7-1.0), and for those drinking 5 or more cups was 0.7 (95% CI 0.5-0.9); these ORs decreased linearly (P = 0.008). The reduced risk estimates were more pronounced with cancer of the proximal colon than the distal colon. Rectal cancer risk was not associated with either coffee or tea. Coffee consumption was observed to have a different relationship for each of the cancer sites and tea consumption was not related to any cancer site.     

Family history of cancer and risk of colorectal cancer in Italy.

Subjects with a family history of colorectal cancer (CRC) are at increased risk of CRC, but quantification of the risk in different populations, the possible differences in risk according to localization of the cancer and the association of family history of other cancers with CRC risk are still open issues. We have therefore analysed data from a multicentric case-control study conducted in six Italian areas between 1992 and 1996 of 1225 incident cases of colon cancer, 728 cases of rectal cancer and 4154 controls admitted for acute conditions to the same network of hospitals as the cases. Unconditional logistic regression models including terms for gender, age, study centre, years of education and number of siblings were used to estimate the odds ratios (ORs) of CRC according to various aspects of history of CRC and other cancers in first-degree relatives. The OR for family history of CRC was 3.2 (95% confidence interval, CI, 2.5-4.1) for colon cancer and 2.2 (95% CI 1.6-3.1) for rectal cancer. Colon cancer was significantly associated with a family history of stomach (OR 1.4), bone (OR 2.1) and kidney (OR 2.3) cancers, while rectal cancer was significantly associated with a family history of lymphomas (OR 2.8). There was a 30% higher risk of colon and rectal cancer in subjects with a family history of any cancer, excluding intestine. The ORs for family history of CRC were 5.2 for colon and 6.3 for rectum when the proband''s age was below 45 years. The ORs were similar when the affected relative was a parent or a sibling and in different strata of age of relative(s). For subjects with two or more first-degree relatives with CRC, the risk was 6.9 for the right colon, 5.8 for the transverse and descending colon, 3.8 for the sigma, 3.2 for the rectosigmoid junction and 1.9 for the rectum. This study confirms that a family history of CRC in first-degree relatives increases the risk of both colon and rectal cancer, the association being stronger at younger ages and for right colon.     

Tea and coffee consumption and the risk of digestive tract cancers: data from a comparative case-referent study in Japan

Objectives: The purpose of this study was to examine the hypothesis that tea and coffee consumption have a protective effect against development of digestive tract cancers. Methods: A comparative case-referent study was conducted using Hospital-based Epidemiologic Research Program at Aichi Cancer Center (HERPACC) data from 1990 to 1995 in Nagoya, Japan. This study comprised 1,706 histologically diagnosed cases of digestive tract cancers (185 esophagus, 893 stomach, 362 colon, 266 rectum) and a total of 21,128 non-cancer outpatients aged 40 years and over. Logistic regression was used to analyze the data, adjusting for gender; age; year and season at hospital-visit; habitual smoking and alcohol drinking; regular physical exercise; fruit, rice, and beef intake; and beverage intake. Results: The odds ratio (OR) of stomach cancer decreased to 0.69 (95 percent confidence interval [CI] = 0.48-1.00) with high intake of green tea (seven cups or more per day). A decreased risk was also observed for rectal cancer with three cups or more daily intake of coffee (OR = 0.46, CI = 0.26-0.81). Conclusions: The results suggest the potential for protective effect against site-specific digestive tract cancer by consumption of green tea and coffee, although most associations are limited only to the upper category of intake and have no clear explanation for site-specificity.     

Diabetes mellitus as a risk factor for gastrointestinal cancers among postmenopausal women

Objectives

While diabetes has been linked to several cancers in the gastrointestinal (GI) tract, findings have been mixed for sites other than colorectal and liver cancer. We used the Women’s Health Initiative (WHI) data and conducted a comprehensive assessment of associations between diabetes and GI malignancy (esophagus, stomach, liver, biliary, pancreas, colon, and rectal).

Methods

A total of 145,765 postmenopausal women aged 50–79 enrolled in the WHI were followed for a mean 10.3 years. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs) for the association between GI cancers and diagnosed diabetes, including its duration and treatment.

Results

Diabetes at enrollment was associated with increased risk of liver (HR = 2.97; 95 % CI, 1.66–5.32), pancreatic (HR = 1.62; 95 % CI, 1.15–2.30), colon (HR = 1.38; 95 % CI, 1.14–1.66), and rectal (HR = 1.87, 95 % CI: 1.22–2.85) cancer. Diabetes severity, assessed by duration or need for pharmacotherapy, appeared to have stronger links to risk of liver, pancreatic, and rectal cancer, but not colon cancer. There was no statistically significant association of diabetes with biliary, esophageal, and stomach cancers.

Conclusion

Type 2 diabetes is associated with a significantly increased risk of cancers of the liver, pancreas, colon, and rectum in postmenopausal women. The suggestion that diabetes severity further increases these cancer risks requires future studies.     

Black tea consumption and cancer risk: a prospective study

In a prospective cohort study, men of Japanese ancestry were clinically examined from 1965 to 1968. For 7,833 of these men, data on black tea consumption habits were recorded. Since 1965, newly diagnosed cancer incidence cases have been identified: 152 colon, 151 lung, 149 prostate, 136 stomach, 76 rectum, 57 bladder, 30 pancreas, 25 liver, 12 kidney and 163 at other (miscellaneous) sites. Compared to almost-never drinkers, men habitually drinking black tea more than once/day had an increased relative risk (RR) for rectal cancer (RR = 4.2). This positive association (P = 0.0007) could not be accounted for by age or alcohol intake. We also observed a weaker but significant negative association of black tea intake and prostate cancer incidence (P = 0.020). There were no significant associations between black tea consumption and cancer at any other site.     

Radiation risk of incident colorectal cancer by anatomical site among atomic bomb survivors: 1958–2009

Radiation effects on colorectal cancer rates, adjusted for smoking, alcohol intake and frequency of meat consumption and body mass index (BMI) by anatomical subsite (proximal colon, distal colon and rectum) were examined in a cohort of 105,444 atomic bomb survivors. Poisson regression methods were used to describe radiation-associated excess relative risks (ERR) and excess absolute rates (EAR) for the 1958–2009 period. There were 2,960 first primary colorectal cancers including 894 proximal, 871 distal and 1,046 rectal cancers. Smoking, alcohol intake and BMI were associated with subsite-specific cancer background rates. Significant linear dose–responses were found for total colon (sex-averaged ERR/Gy for 70 years old exposed at age 30 = 0.63, 95% confidence interval [CI]: 0.34; 0.98), proximal [ERR = 0.80, 95% CI: 0.32; 1.44] and distal colon cancers [ERR = 0.50, 95% CI: 0.04; 0.97], but not for rectal cancer [ERR = 0.023, 95% CI: −0.081; 0.13]. The ERRs for proximal and distal colon cancers were not significantly different (p = 0.41). The ERR decreased with attained age for total colon, but not for proximal colon cancer, and with calendar year for distal colon cancer. The ERRs and EARs did not vary by age at exposure, except for decreasing trend in EAR for proximal colon cancer. In conclusion, ionizing radiation is associated with increased risk of proximal and distal colon cancers. The ERR for proximal cancer persists over time, but that for distal colon cancer decreases. There continues to be no indication of radiation effects on rectal cancer incidence in this population.     

Cancer of the large bowel in women in relation to alcohol consumption: a case-control study in Wisconsin (United States)

Age-specific consumption of beer, wine, and liquor was ascertained by telephone interview from 779 women in Wisconsin (United States) with newly reported diagnosis of carcinoma of the colon and rectum. Population controls (n=2,315) interviewed for this case-control study were randomly selected from Wisconsin driver's license files and Health Care Financing Administration files. Overall, there was a modest indication that high levels of alcohol consumption (11 or more drinks per week) were associated with increased risk of large bowel cancer (adjusted odds ratio [OR]=1.47,95 percent confidence interval [CI]=1.0–2.22). In site-specific analyses, only rectal cancer demonstrated a significant linear trend (P=0.01) with increasing consumption. Significant beverage-specific effects were observed for liquor and colon cancer: the adjusted ORs for 1–2, 3–5, and 6+ drinks per week were 1.12, 1.68, 1.51, respectively (P trend = 0.01). Beer was associated significantly with rectal cancer: the adjusted ORs for 1–2, 3–5, 6–10, and 11+ drinks per week were 1.25, 1.25, 1.58, 2.42, respectively (P trend = 0.02). Wine consumption was associated inversely with these cancers. These relationships appeared to be consistent for recent, past, and total lifetime consumption, and were not attributable to differences in dietary habits.Authors are with the University of Wisconsin-Madison Comprehensive Cancer Canter, Madison, WI, USA. Address correspondence to Dr Newcomb, University of Wisconsin-Madison Comprehensive Cancer Center, 1300 University Avenue 4780, Madison, WI 53706, USA. Supported in part by the Alcoholic Beverage Medical Research Foundation and American Cancer Society Grant Number SIG-15. An earlier version of this paper was presented to the 24th Annual Meeting of the Society for Epidemiologic Research, Buffalo, New York, June 1991, and the 10th Anniversary of the Alcoholic Beverage Medical Research Foundation, Baltimore, MD, April 1992.     

Coffee consumption and risk of colorectal cancer in a population-based prospective cohort of Japanese men and women

We prospectively examined the association between coffee consumption and the risk of developing colorectal cancer in a large population-based cohort study (the JPHC Study) of Japanese men and women. Data were analyzed from a population-based cohort of 96,162 subjects (46,023 men and 50,139 women). A total of 1,163 incident colorectal cancers were identified during the follow-up period, including 763 cases of colon cancer and 400 of rectal cancer. We observed a significant inverse association between coffee consumption and the risk of developing invasive colon cancer among women. Compared with those who almost never consumed coffee, women who regularly consumed 3 or more cups of coffee per day had a RR of 0.44 (95% CI = 0.19-1.04; p for trend = 0.04) after adjustment for potential confounding factors. However, no significant association was found for rectal cancer in women. In men, no significant decrease was observed in any colorectal cancer site. Further, additional analyses on the association of green tea consumption with colorectal cancer risk found no significant association in men or women. These findings suggest that coffee consumption may lower the risk of colon cancer among Japanese women.     

Tea consumption and breast cancer risk in a cohort of women with family history of breast cancer

Laboratory studies have observed chemopreventive effects of black and green tea on breast cancer development, but few epidemiologic studies have identified such effects. We investigated the association between tea consumption and breast cancer risk using data from 45,744 U.S. and Puerto Rican women participating in the Sister Study. Frequency and serving size of black and green tea consumption were measured at cohort enrollment. Breast cancer diagnoses were reported during follow-up and confirmed by medical record review. Multivariable Cox proportional hazards regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI). We further investigated potential variation according to estrogen receptor (ER) status, menopausal status and body mass index (BMI). Overall, 81.6 and 56.0% of women drank black or green tea, respectively. A total of 2,809 breast cancer cases were identified in the cohort. The multivariable model suggested an inverse association between black (≥5 vs. 0 cups/week: HR = 0.88, 95% CI 0.78, 1.00, p-trend = 0.08) and green tea (≥5 vs. 0 cups/week: HR = 0.82, 95% CI 0.70, 0.95, p-trend < 0.01) consumption and breast cancer risk. We did not observe differences by ER characteristics, menopausal status or BMI. In conclusion, our study suggests drinking at least five cups of green or black tea per week may be associated with decreased breast cancer risk.     

Green tea, black tea and colorectal cancer risk: a meta-analysis of epidemiologic studies

Experimental studies have supported tea as a chemopreventive agent for colorectal cancer. No quantitative summary of the epidemiologic evidence on tea and colorectal cancer risk has ever been performed. The current meta-analysis included 25 papers conducted in 11 countries across three continents (North America, Asia and Europe). Summary odds ratios (ORs) for highest versus non/lowest tea consumption levels were calculated based on fixed and random effects models. The meta-regression and stratified methods were used to examine heterogeneity across studies. For green tea, the combined results from eight studies indicated a reduced risk of colorectal cancer with intake [summary OR = 0.82, 95% confidence interval (CI) = 0.69-0.98]. The protective effect is mainly found among the three case-control studies of colon cancer (summary OR = 0.74, 95% CI = 0.60-0.93). Results from studies of rectal cancer irrespective of study design (case-control versus cohort) (summary OR = 0.99, 95% CI = 0.71-1.37) and cohort studies of colon cancer (summary OR = 0.99, 95% CI = 0.79-1.24) were compatible with the null hypothesis. For black tea, the summary OR derived from 20 studies was 0.99 (95% CI = 0.87-1.13). There is wide divergence in results across the 20 individual studies; formal tests for homogeneity across studies revealed statistically significant differences in findings across all studies (P < 0.001), amongst the 7 cohort studies (P = 0.002), and amongst the 13 case-control studies (P < 0.001). Despite the strong evidence from in vitro and non-human in vivo studies in support of green and black tea as potential chemopreventive agents against colorectal cancer, available epidemiologic data are insufficient to conclude that either tea type may protect against colorectal cancer in humans.     

Prospective cohort study of green tea consumption and colorectal cancer risk in women.

Tea and its constituents have shown anticarcinogenic activities in in vitro and animal studies. Epidemiologic studies, however, have been inconsistent. We prospectively evaluated the association between green tea consumption and colorectal cancer (CRC) risk in a cohort of 69,710 Chinese women aged 40 to 70 years. Information on tea consumption was assessed through in-person interviews at baseline and reassessed 2 to 3 years later in a follow-up survey. During 6 years of follow-up, 256 incident cases of CRC were identified. The multivariate relative risk of CRC was 0.63 (95% confidence interval, 0.45-0.88) for women who reported drinking green tea regularly at baseline compared with nonregular tea drinkers. A significant dose-response relationship was found for both the amount of tea consumed (Ptrend = 0.01) and duration in years of lifetime tea consumption (Ptrend = 0.006). The reduction in risk was most evident among those who consistently reported to drink tea regularly at both the baseline and follow-up surveys (relative risk, 0.43; 95% confidence interval, 0.24-0.77). The inverse association with regular tea drinking was observed for both colon and rectal cancers. This study suggests that regular consumption of green tea may reduce CRC risk in women.     

Dietary cholesterol intake and cancer

BackgroundThis study assesses the association between dietary cholesterol intake and the risk of various cancers.Patients and methodsMailed questionnaires were completed between 1994 and 1997 in eight Canadian provinces by 1182 incident histologically confirmed cases of the stomach, 1727 of the colon, 1447 of the rectum, 628 of the pancreas, 3341 of the lung, 2362 of the breast, 442 of the ovary, 1799 of the prostate, 686 of the testis, 1345 of the kidney, 1029 of the bladder, 1009 of the brain, 1666 non-Hodgkin's lymphomas (NHL), 1069 leukemia and 5039 population controls. Information on dietary habits and nutrition intake were obtained using a food frequency questionnaire, which provided data on eating habits 2 years before the study. Odds ratios (ORs) were derived by unconditional logistic regression to adjust for total energy intake and other potential confounding factors.ResultsDietary cholesterol was positively associated with the risk of cancers of the stomach, colon, rectum, pancreas, lung, breast (mainly postmenopausal), kidney, bladder and NHL: the ORs for the highest versus the lowest quartile ranged from 1.4 to 1.7. In contrast, cholesterol intake was inversely associated with prostate cancer.ConclusionsOur findings add to the evidence that high cholesterol intake is linked to increased risk of various cancers. A diet low in cholesterol may play a role in the prevention of several cancers.     

Dietary catechins and cancer incidence among postmenopausal women: the Iowa Women's Health Study (United States)

Objective: Catechins are bioactive flavonoids present in tea, fruits, and vegetables. Previous epidemiological studies regarding tea and cancer risk were inconclusive, possibly because catechins are also present in other plant foods. We investigated whether a high intake of catechins are associated with cancer incidence among postmenopausal women. Methods: A cohort of 34,651 postmenopausal cancer-free women aged 55–69 years were followed from 1986 to 1998. At baseline, data on diet, medical history, and lifestyle were collected. Incident cancers were obtained through linkage with a cancer registry. Cox proportional hazards analysis was used to estimate risk ratios. Results: After adjustment for potential confounders, catechin intake was inversely associated with rectal cancer incidence only (risk ratios from lowest to highest quartile: 1.00, 0.93, 0.73, and 0.55; p for trend 0.02). Non-significant inverse trends were found for cancer of the upper digestive tract, pancreas, and for hematopoietic cancers. Catechins derived primarily from fruits, (+)-catechin and (–)-epicatechin, tended to be inversely associated with upper digestive tract cancer, whereas catechins derived from tea were inversely associated with rectal cancer. Conclusions: Among several cancers studied, our data suggest that catechin intake may protect against rectal cancer. The distinct effects found for catechins derived from solid foods (fruits) and beverages (tea) may be due to differences in bioavailability or metabolism of the catechins, or to their interactions with other dietary components.     

Effects of alcohol consumption on the risk of colorectal cancer among men by anatomical subsite (Canada)

Objective: To estimate the effects of alcohol consumption on the risk of colorectal cancer according to anatomical subsite. Methods: Between 1979 and 1985 a population-based case–control study of cancer at multiple sites was carried out in Montréal. This analysis was restricted to the 585 cases with adenocarcinoma of the large bowel, aged 35–70 years, who underwent face-to-face interviews. Controls (n = 500) were selected either from electoral lists or by random-digit dialing and were frequency-matched to the cases on age. Polytomous logistic regression was used to estimate the risk of cancer of the proximal colon, distal colon, and rectum in relation to the consumption of alcoholic beverages. Results: Daily consumption of alcohol of any type was associated with increased risks of cancer of the distal colon [odds ratio (OR) = 2.3; 95% confidence interval (CI) 1.4–3.7] and the rectum (OR = 1.6; 95% CI 1.0–2.6), but not with an increased risk of cancer of the proximal colon (OR = 1.0; 95% CI: 0.6–1.7). When type of beverage was considered, beer showed strong associations with cancer at all three subsites (ORs among the heaviest drinkers ranging from 1.8 to 2.4), spirits showed weaker associations with cancer at all three subsites (ORs ranging from 1.4 to 1.6), and wine showed null associations. Conclusions: The results are consistent with the hypothesis that consumption of alcoholic beverages increases the risk of colorectal cancer. The evidence is strongest for effects on the distal colon and rectum, and, among the three types of beverage, it most strongly implicates beer.