Body fatness at an early age and risk of colorectal cancer

While there is convincing evidence that excess body fatness in adulthood is positively associated with colorectal cancer risk, the association between body fatness at an early age (≤30 years) and the risk of colorectal cancer has been equivocal. The present meta‐analysis was performed to clarify this association. PubMed and Web of Science databases were searched for relevant studies that investigated this association. The risk estimates from each study were transformed into a continuous variable for each 5 kg/m² increase in body mass index (BMI). A random effects model was used to calculate the summary relative risks (RRs) with 95% confidence intervals (CIs). A total of 15 observational studies (13 cohort studies and two case‐control studies) were included in this meta‐analysis. Each 5 kg/m² increase in BMI was significantly associated with a 13% (RR 1.13, 95% CI 1.08, 1.19), 17% (RR 1.17, 95% CI 1.09, 1.25) and 8% (RR 1.08, 95% CI 1.04, 1.11) higher risk of colorectal cancer overall, in men, and in women, respectively. Substantial heterogeneity was observed across studies. Based on the anatomic subsite, each 5 kg/m² increase in BMI was significantly associated with a 14% (RR 1.14, 95% CI 1.07, 1.22) higher risk of colon cancer, whereas no association (RR 1.03, 95% CI 0.95, 1.13) was observed with rectal cancer. In summary, body fatness at an early age may affect colon cancer risk later in life. Prevention of overweight and obesity in young individuals should be emphasized to prevent early‐onset colon cancer attributed to excess body fatness.     

Alcohol consumption, type of alcoholic beverage and risk of colorectal cancer at specific subsites

Within the Netherlands Cohort Study on diet and cancer, we investigated associations between total alcohol consumption, specific alcoholic beverage consumption and risk of colorectal cancer (CRC) according to anatomical subsite. Hazard Ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models. Analyses were performed on 2,323 CRC cases, available after 13.3 years of follow-up. Compared to abstaining, alcohol consumption of >/=30.0 g/day ( approximately 3 alcoholic drinks) was positively associated with the risk of CRC (HR: 1.32, 95% CI: 1.06-1.65). Analyses restricted to subjects who reported to have consumed equal amounts of alcohol 5 years before baseline compared to baseline, showed elevated risk estimates for consumers of >/=30.0 g of total alcohol per day as well (HR: 1.53, 95% CI: 1.16-2.01). Suggestive of a subsite-specific effect, cancer risk seemed to increase from proximal colon through rectum; HR: 1.29, 95% CI: 0.85-1.96 for proximal colon cancer, HR: 1.41, 95% CI: 0.94-2.11 for distal colon cancer, HR: 2.07, 95% CI: 1.03-4.18 for rectosigmoid cancer and HR: 1.69, 95% CI: 1.08-2.64 for rectal cancer. No associations were observed between consumption of alcoholic beverages and CRC risk when compared with the nondrinkers of the specific beverage and after adjustment for total alcohol intake. No evidence was found for sex-specific effects of alcohol and alcoholic beverages. In conclusion, our data showed a positive association between alcohol consumption and risk of CRC, which seemed to be mainly explained by the alcoholic content of alcoholic beverages, rather than other constituents. Also, cancer risk may vary according to anatomical subsite.     

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.     

The association of diabetes with colorectal cancer risk: the Multiethnic Cohort

Background:

Diabetics have been found to have a greater risk of colorectal cancer than non-diabetics.

Methods:

We examined whether this relationship differed by ethnic group, cancer site or tumour stage in a population-based prospective cohort, including 3549 incident colorectal cancer cases identified over a 13-year period (1993–2006) among 199 143 European American, African American, Native Hawaiian, Japanese American and Latino men and women in the Multiethnic Cohort.

Results:

Diabetics overall had a significantly greater risk of colorectal cancer than did non-diabetics (relative risk (RR)=1.19, 95% confidence interval (CI)=1.09–1.29, P-value (P)<0.001). Positive associations were observed for colon cancer, cancers of both the right and left colon, and cancers diagnosed at a localised and regional/distant stage. The association with colorectal cancer risk was significantly modified by smoking status (P_Interaction=0.0044), with the RR being higher in never smokers (RR=1.32, 95% CI=1.15–1.53, P<0.001) than past (RR=1.19, 95% CI=1.05–1.34, P=0.007) and current smokers (RR=0.90, 95% CI=0.70–1.15, P=0.40).

Conclusion:

These findings provide strong support for the hypothesis that diabetes is a risk factor for colorectal cancer.     

Yogurt consumption and risk of colorectal cancer in the Italian European prospective investigation into cancer and nutrition cohort

Fermented dairy products like yogurt have been suggested to protect against colorectal cancer (CRC). We conducted a prospective study on 45,241 (14,178 men; 31,063 women) volunteers of the EPIC-Italy cohort who completed a dietary questionnaire including specific questions on yogurt intake. During 12 years of follow-up, 289 volunteers were diagnosed with CRC. Hazard ratios (HRs) for the disease and 95% confidence intervals (CIs) were estimated by Cox proportional hazard models, stratified by dietary questionnaire and adjusted for energy intake and other potential confounders. Yogurt intake was inversely associated with CRC risk. For the energy-adjusted model, HR for CRC in the highest versus lowest tertile of yogurt intake was 0.62 (95% CI, 0.46-0.83). In the full model adjusted for energy, simple sugar, calcium, fiber, animal fat, alcohol and red meat intake, as well as body mass index, smoking, education and physical activity, HR was 0.65 (95% CI, 0.48-0.89) in the highest versus lowest tertile. The protective effect of yogurt was evident in the entire cohort, but was stronger in men, although there was no interaction of sex with the yogurt-CRC association (p(interaction) 0.20, fully adjusted model). In our prospective study, high yogurt intake was significantly associated with decreased CRC risk, suggesting that yogurt should be part of a diet to prevent the disease. Investigation of larger cohorts is necessary to reveal any residual confounding of the association of yogurt intake with CRC risk.     

Gender differences in colorectal cancer: implications for age at initiation of screening

There is some variation regarding age at initiation of screening for colorectal cancer (CRC) between countries, but the same age of initiation is generally recommended for women and men within countries, despite important gender differences in the epidemiology of CRC. We have explored whether, and to what extent, these differences would be relevant regarding age at initiation of CRC screening. Using population-based cancer registry data from the US and national mortality statistics from different countries, we looked at cumulative 10-year incidence and mortality of CRC reached among men at ages 50, 55, and 60, and found that women mainly reached equivalent levels when 4 to 8 years older. The gender differences were remarkably constant across populations and over time. These patterns suggest that gender differentiation of age at initiation may be worthwhile to utilise CRC-screening resources more efficiently.     

Meat consumption and colorectal cancer risk in Japan: The Takayama study

Compared with the abundant data from Western countries, evidence regarding meat consumption and colorectal cancer is limited in the Japanese population. We evaluated colorectal cancer risk in relation to meat consumption in a population‐based prospective cohort study in Japan. Participants were 13 957 men and 16 374 women aged ≥35 years in September 1992. Meat intake, assessed with a validated food frequency questionnaire, was controlled for the total energy intake. The incidence of colorectal cancer was confirmed through regional population‐based cancer registries and histological identification from colonoscopy in two main hospitals in the study area. From September 1992 to March 2008, 429 men and 343 women developed colorectal cancer. After adjustments for multiple confounders, a significantly increased relative risk of colorectal cancer was observed in the highest versus lowest quartile of the intake of total and red meat among men; the estimated hazard ratios were 1.36 (95% CI: 1.03, 1.79) for total meat (P for trend = 0.022), and 1.44 (95% CI: 1.10, 1.89) for red meat (P for trend = 0.009). A positive association between processed meat intake and colon cancer risk was also observed in men. There was no significant association between colorectal cancer and meat consumption in women. These results suggest that the intake of red and processed meat increases the risk of colorectal or colon cancer among Japanese men. Abstaining from excessive consumption of meat might be protective against developing colorectal cancer.     

Cigarette smoking and risk of colorectal cancer among Norwegian women

Objective  The association between cigarette smoking and colorectal cancer (CRC) is still not established. In 2002, Norwegian women had the second highest incidence of CRC in the world. A large proportion of Norwegian women are ever smokers. We examined the association between cigarette smoking and CRC incidence among Norwegian women. Methods  We followed 68,160 women, aged 30–69 years, from the Norwegian Women and Cancer Study who completed a questionnaire in 1996 or 1998 by linkages to national registers through 31 December 2005. Rate ratios (RRs) and 95% confidence intervals (CIs) were estimated by fitting Cox proportional hazard models. Subsequently, we estimated the population attributable fraction. Results  Altogether, 425 incident cases of primary, invasive CRC were identified. Ever smokers had a 20% increased risk of CRC (RR = 1.2; 95% CI = 1.0–1.5), a 30% increased risk of colon (RR = 1.3; 95% CI = 1.0–1.7), and a 10% increased risk of rectal (RR = 1.1; 95% CI = 0.7–1.5) cancer compared to never smokers. The population attributable fraction was estimated to be 12% which indicated that approximately one in eight of the CRC cases could have been prevented at a population level. Conclusion  Our results support the hypothesis that cigarette smoking is a preventable cause of CRC among women.     

Folate and colorectal cancer prevention

Anti-folate chemotherapy agents such as methotrexate and fluorouracil reduce proliferation of neoplastic cells by inhibiting DNA synthesis. Paradoxically epidemiological data suggests an inverse relationship between dietary folate intake and incidence of colorectal cancer (CRC). On the basis of this and other putative health benefits around 35% of the North American population take folic acid supplements, in addition to natural food folates and fortified flour and cereal grains. Recently, randomised controlled trials investigating folic acid as a secondary preventative agent in colorectal neoplasia have shed further light on the relationship between folate and colorectal carcinogenesis, corroborating data from animal models indicating opposing effects dependent on the timing of exposure in relation to the development of neoplastic foci. A ‘dual-modulator'' role for folate in colorectal carcinogenesis has been proposed in which moderate dietary increases initiated before the establishment of neoplastic foci have a protective influence, whereas excessive intake or increased intake once early lesions are established increases tumorigenesis. Functional polymorphic variants in genes encoding key enzymes in the folate metabolic pathway add a further layer of complexity to the relationship between folate and CRC risk. Here, we review the evidence concerning the efficacy and safety of folate as a potential CRC chemopreventive agent.     

Diet and risk of colorectal cancer in a cohort of Finnish men

Objectives: Based on previous epidemiological studies, high fat and meat consumption may increase and fiber, calcium, and vegetable consumption may decrease the risk of colorectal cancer. We sought to address these hypotheses in a male Finnish cohort.Methods: We analyzed data from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study) where 27, 111 male smokers completed a validated dietary questionnaire at baseline. After an average of 8 years of follow-up, we documented 185 cases of colorectal cancer. The analyses were carried out using the Cox proportional hazards model.Results: The relative risk (RR) for men in the highest quartile of calcium intake compared with men in the lowest quartile was 0.6 (95% CI 0.4–0.9, p for trend 0.04). Likewise, the intake of milk protein and the consumption of milk products was inversely associated with risk of colorectal cancer. However, intake of dietary fiber was not associated with risk, nor was fat intake. Consumption of meat or different types of meat, and fried meat, fruits or vegetables were not associated with risk.Conclusions: In this cohort of men consuming a diet high in fat, meat, and fiber and low in vegetables, high calcium intake was associated with lowered risk of colorectal cancer.     

Reported behavior of eating anything at anytime and risk of colorectal cancer in women

Although numerous studies have assessed the effect of foods and nutrients on colorectal carcinogenesis, few studies have investigated human eating behavior in relation to risk of colorectal cancer. In our study, we assessed whether the reported behavior of eating anything at anytime influenced colorectal cancer risk and related plasma biomarkers. We prospectively followed up 55,540 women in the Nurses' Health Study who were aged 48-73 years, had no history of cancer, ulcerative colitis or diabetes and responded to the item "I eat anything I want, anytime I want" in the 1994 questionnaire. We also analyzed blood samples for 1,994 women, which were collected in 1989-1990. During 12 years of follow-up, 552 colorectal cancer cases were documented. After adjusting for age, smoking, body mass index, physical activity, red and processed meat and other known risk factors for colorectal cancer, women who reported eating anything at anytime experienced an increased risk of colorectal cancer (relative risk = 1.28, 95% confidence interval = 1.06-1.56) compared to those who did not report this behavior. In addition, reporting eating anything at anytime was associated with higher fasting plasma levels of insulin (p = 0.04) and C-peptide (p = 0.05). In conclusion, reports of eating anything at anytime are associated with an increased risk of colorectal cancer in this large prospective cohort study, independent of other potential risk factors for colorectal cancer.     

Alcohol consumption and risk of colorectal cancer in a cohort of Finnish men

We investigated the association between self-reported alcohol ingestion and colorectal cancer in a cohort of male smokers in Finland. Among 27,109 men aged 50 to 69 years, 87 colon and 53 rectal cases were diagnosed during the five to eight years of follow-up. Among drinkers, colorectal cancer risk increased with the amount of alcohol consumed (P trend = 0.01) with risk increasing by 17 percent for each drink consumed. Both beer and spirits contributed to this increased risk. Further analyses revealed that the positive association with alcohol was primarily for colon cancer (P trend = 0.01). Interestingly, risk of colorectal cancer associated with drinking (cf self-reported abstinence) changed with follow-up time, suggesting an inverse association for alcohol early in follow-up, and a positive association after about three-and-a-half years of follow-up. Follow-up time did not modify the positive association with amount of alcohol among drinkers, however. Results also indicated that -carotene supplementation may attenuate the effect of alcohol on colorectal cancer risk among drinkers. In conclusion, this study supports a role for alcohol in colon carcinogenesis and suggests that similar studies should evaluate carefully the effects of lifetime drinking habits and recent abstinence.Drs Glynn, Albanes, Brown, Tangrea, and Taylor are with the Division of Cancer Prevention and Control, National Cancer Institute, Bethesda, MD, USA. Drs Pietinen, Rautalahti, and Virtamo are with the National Public Health Institute, Helsinki, Finland. Address correspondence to Dr Glynn, NCI:DCPC:CPRP:CPSB, Executive Plaza North, Suite 211, 6130 Executive Blvd. MSC 7326, Bethesda, MD 20892-7326, USA.This study was supported by a contract (NO1-CN-45165) with the US National Cancer Institute.     

Adiponectin and adiponectin receptor in relation to colorectal cancer progression

Although obesity is a risk factor for colorectal cancer, the underlying mechanism is not clear. Adiponectin is an adipokine that binds to 2 types of receptors, AdipoR1 and AdipoR2. The plasma concentrations of adiponectin are reduced in obese individuals and adiponectin has been reported to have anticarcinogenic properties. Furthermore, AdipoR1 and AdipoR2 have been reported to be expressed in several malignancies. However, little is known about the expression of AdipoR1 and AdipoR2 in colorectal cancer and its clinicopathological implications. In addition, the relationship between adiponectin and colorectal cancer has not yet been determined. Here, we sought to investigate adiponectin and adiponectin receptors in relation to colorectal cancer. AdipoR1 and AdipoR2 immunostaining was detected in 72 and 68% of human colorectal cancer tissue, respectively. AdipoR1 and AdipoR2 expression levels were inversely related to T stage. The lowest AdipoR1 and AdipoR2 expression were detected in poorly differentiated adenocarcinoma. RT-PCR also showed the expression of AdipoR1 and AdipoR2 in HCT116 and SW620. MTT assay and TUNEL assay demonstrated the tendency of growth inhibition and apoptosis induction in both cell lines after full-length adiponectin treatment although statistically insignificant. Microarray analysis revealed several gene responses to full-length adiponectin, including upregulation of ENDOGL1 and MT1G. In conclusion, AdipoR1 and AdipoR2 may be intimately related to the progression of colorectal cancer. Further studies may be warranted to assess adiponectin and its receptors as a novel target for inhibition of colorectal cancer growth.     

Dietary glycemic load, glycemic index and colorectal cancer risk: results from the Netherlands Cohort Study

Since hyperinsulinemia is implicated in the development of colorectal cancer, determinants of serum insulin levels, like the glycemic load and the glycemic index of the diet, could influence cancer risk. Our objective was to evaluate whether a diet with a high glycemic load or glycemic index is associated with increased colorectal cancer risk. In the Netherlands Cohort Study, 120,852 subjects completed a food frequency questionnaire in 1986. After 11.3 years of follow-up, 1,225 colon and 418 rectal cancer cases were available for analysis. A case-cohort approach was used to estimate multivariate adjusted rate ratios and 95% confidence intervals for quintiles of energy-adjusted glycemic load and glycemic index. The RR for colorectal cancer comparing the highest versus the lowest quintile levels of glycemic load and glycemic index were 0.83 (95% CI: 0.64-1.08) and 0.81 (95% CI: 0.61-1.08) for men and 1.00 (95% CI: 0.73-1.36) and 1.20 (95% CI: 0.85-1.67) for women. In general, no clear associations with cancer subsites were observed. Glycemic load and glycemic index were borderline significantly associated with an increased risk of proximal colon cancer in women (p-trend = 0.06 and 0.08, respectively), however, these associations were attenuated after exclusion of the first 2 years of follow-up (p-trend = 0.165 and 0.254, respectively). In men, glycemic index was associated with a reduced risk of distal colon cancer (p-trend = 0.03). Overall, our findings do not support the hypothesis that a diet with a high glycemic load or index is associated with a higher risk of colorectal cancer.     

Endogenous sex hormones and colorectal cancer survival among men and women

Although previous studies have suggested a potential role of sex hormones in the etiology of colorectal cancer (CRC), no study has yet examined the associations between circulating sex hormones and survival among CRC patients. We prospectively assessed the associations of prediagnostic plasma concentrations of estrone, estradiol, free estradiol, testosterone, free testosterone and sex hormone-binding globulin (SHBG) with CRC-specific and overall mortality among 609 CRC patients (370 men and 239 postmenopausal women not taking hormone therapy at blood collection) from four U.S. cohorts. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard regression. We identified 174 deaths (83 CRC-specific deaths) in men and 106 deaths (70 CRC-specific deaths) in women. In men, higher circulating level of free testosterone was associated with lower risk of overall (the highest vs. lowest tertiles, HR = 0.66, 95% CI, 0.45–0.99, p_trend = 0.04) and possibly CRC-specific mortality (HR = 0.73, 95% CI, 0.41–1.29, p_trend = 0.27). We generally observed nonsignificant inverse associations for other sex steroids, and a positive association for SHBG with CRC-specific mortality among male patients. In women, however, we found a suggestive positive association of estrone with overall (HR = 1.54, 95% CI, 0.92–2.60, p_trend = 0.11) and CRC-specific mortality (HR = 1.96, 95% CI, 1.01–3.84, p_trend = 0.06). Total estradiol, free estradiol and free testosterone were generally suggestively associated with higher risk of mortality among female patients, although not statistically significant. These findings implicated a potential role of endogenous sex hormones in CRC prognosis, which warrant further investigation.     

Postmenopausal endometrial cancer risk and body size in early life and middle age: prospective cohort study

Background:

Greater adiposity in early life has been linked to increased endometrial cancer risk in later life, but the extent to which this association is mediated through adiposity in later life is unclear.

Methods:

Among postmenopausal women who had never used menopausal hormone therapies and reported not having had a hysterectomy, adjusted relative risks (RRs) of endometrial cancer were estimated using Cox regression.

Results:

Among 249 791 postmenopausal women with 7.3 years of follow-up on average (1.8 million person-years), endometrial cancer risk (n=1410 cases) was strongly associated with current body mass index (BMI) at baseline (RR=1.87 per 5 kg m⁻² increase in BMI, 95% confidence interval (CI): 1.77–1.96). Compared with women thinner than average at age 10, the increased risk among women plumper at age 10 (RR=1.27, 95% CI: 1.09–1.49) disappeared after adjustment for current BMI (RR=0.90, 95% CI: 0.77–1.06). Similarly, compared with women with clothes size 12 or less at age 20, the increased risk among women with clothes size 16 or larger (RR=1.87, 95% CI: 1.61–2.18) was not significant after adjustment for current BMI (RR=1.03, 95% CI: 0.88–1.22).

Conclusion:

Among women who have never used hormone therapy for menopause, the association between body size in early life and endometrial cancer risk in postmenopausal women can be largely explained by women''s current BMI.     

Italian mediterranean index and risk of colorectal cancer in the Italian section of the EPIC cohort

Colorectal cancer is among the commonest cancers worldwide. Dietary factors have been linked to colorectal cancer risk, however, few studies have evaluated the relationship between a priori dietary patterns and colorectal cancer risk. We evaluated the effect of adherence to a Mediterranean dietary pattern, as measured by the Italian Mediterranean Index, on the risk of colorectal cancer in the 45,275 participants of the Italian section of the EPIC study who completed a dietary questionnaire. Hazard ratios (HRs) with 95% confidence intervals (CIs) for colorectal cancer in relation to categories of Italian Mediterranean Index score were estimated by multivariate Cox models adjusted for known risk factors, on the whole cohort, on men and women and according to cancer subsite. During a mean follow‐up of 11.28 years, 435 colorectal cancer cases were identified. The Italian Mediterranean Index was inversely associated with colorectal cancer risk (HR: 0.50; 95% CI: 0.35–0.71 for the highest category compared to the lowest, P‐trend: 0.043). Results did not differ by sex. Highest Italian Mediterranean Index score was also significantly associated with reduced risks of any colon cancer (HR: 0.54, 95% CI: 0.36–0.81), distal colon cancer (HR: 0.44, 95% CI: 0.26–0.75) and rectal cancer (HR: 0.41, 95% CI: 0.20–0.81), but not of proximal colon cancer. These findings suggest that adherence to a Mediterranean diet (as measured by the Italian Mediterranean Index) protects against colorectal cancer in general but not against cancer developing in the proximal colon.     

Obesity and risk of cancer in Japan

We conducted a population-based prospective cohort study in Japan to examine the relationship between body mass index (BMI) and the risk of incidence of any cancer and of cancer at individual sites. Body mass index was calculated from self-administered body weight and height at baseline. Relative risks (RR) and 95% confidence intervals (CI) were calculated in multivariate proportional-hazards models. Among 27,539 persons (15,054 women and 12,485 men) aged 40 years or older who were free of cancer at enrollment in 1984, 1,672 (668 women and 1,004 men) developed cancer during 9 years of follow-up. In women, after adjustment for potential confounders, the RR of all cancers associated with different BMI, relative to a BMI of 18.5-24.9, were 1.04 (95% CI = 0.85-1.27) for BMI = 25.0-27.4, 1.29 (1.00-1.68) for BMI = 27.5-29.9 and 1.47 (1.06-2.05) for BMI >/=30.0 (p for trend = 0.007). Higher BMI was also significantly associated with higher risk of cancers of the colorectum, breast (postmenopausal), endometrium and gallbladder in women. In men, we observed significantly increased all-cancer risk among only never-smokers. Overweight and obesity could account for 4.5% (all subjects) or 6.2% (never-smokers) of the risk of any cancer in women and -0.2% (all subjects) or 3.7% (never-smokers) in men. The value for women was within the range among women reported from Western populations (3.2%-8.8%). Our data demonstrate that excess weight is a major cancer risk among Japanese women.     

Physical activity and the risk of prostate and testicular cancer: a cohort study of 53,000 Norwegian men

The associations between recreational and occupational physical activity and the subsequent risk of prostate and testicular cancer were examined in a population-based cohort study of 53,242 men in Norway. Age at study entry was 19 to 50 years. Information on physical activity was based on questionnaire responses and a brief clinical examination. A total of 220 prostate and 47 testicular cancer cases were recorded in the Cancer Registry of Norway during a mean follow-up time of 16.3 years. We found a nonsignificant, reduced, adjusted relative risk (RR) of prostate cancer with increased level of physical activity at work and among those men with the greatest recreational physical activity. When occupational and recreational physical activity were combined, a reduced adjusted risk of prostate cancer was observed among men who walked during occupational hours and performed either moderate recreational activity (RR-0.61, 95 percent confidence interval [CI]=0.36 to 1.01) or regular recreational training (RR=0.45, CI=0.20 to 1.01) relative to sedentary men (test for trend,P=0.03). Physically active men who were older than 60 years of age at diagnosis showed a reduced adjusted RR of borderline significance, while no association was observed for younger men. No evidence was found for any association between physical activity and testicular cancer regardless of physical activity at work and recreation.This project is funded by the Norwegian Cancer Society.     

Dietary and biomarker estimates of fatty acids and risk of colorectal cancer

The associations between intake of or circulating fatty acids and risk of colorectal cancer (CRC) are unclear. We examined prospectively the associations between dietary or biomarker fatty acids and CRC. For 41,514 men and women, aged 40–69 years, baseline (1990–94) dietary intakes of fatty acids were estimated using a food frequency questionnaire and plasma phospholipid (PPL) fatty acids were measured for 4,205 participants including 395 CRC cases, according to a case‐cohort design. Hazard ratios were computed using Cox regression adjusting for education, alcohol intake, smoking status, physical activity and total energy intake; and stratified for gender, ethnicity and family history of cancer, with age as the time scale. We assessed the heterogeneity of associations with colon and rectal cancers. PPL saturated fatty acids (SFAs) were positively associated with CRC risk, while total n‐3 polyunsaturated fatty acids (PUFA) and long chain marine n‐3 PUFAs showed inverse associations, significant only for 22:5 n‐3. No significant associations were observed for dietary fatty acid intakes but positive associations with CRC of borderline significance were seen for both dietary and PPL linoleic acid. Positive associations with dietary palmitic acid (16:0), MUFAs and n‐6 PUFAs were seen for rectal but not colon cancers. PPL 22:6 n‐3 was inversely associated with rectal cancer. Limiting intakes of SFAs and MUFAs could be assisted by following existing guidelines to limit red and processed meats which are important sources in the Australian diet. Our observations regarding linoleic acid should be examined further.