Anthropometric variables, physical activity, and incidence of ovarian cancer: The Iowa Women's Health Study

BACKGROUND: Reports on the relation between anthropometric variables (height, weight) and physical activity with ovarian cancer have been inconclusive. The objective of the current study was to extend investigation of potential associations in the Iowa Women's Health Study cohort. METHODS: The relation between self-reported anthropometric variables and incident ovarian cancer was studied in a prospective cohort of women ages 55-69 years who were followed for 15 years. Two hundred twenty-three incident cases of epithelial ovarian cancer were identified by linkage to a cancer registry. RESULTS: No association was found overall between ovarian cancer and height, but a positive association was observed for serous ovarian cancers (relative risk [RR], 1.86 for highest quartile vs. lowest quartile; 95% confidence interval [95% CI], 1.06-3.29). Although current body mass index (BMI) was not associated with ovarian cancer, a BMI > or =30 kg/m2 at age 18 years appeared to be associated positively with ovarian cancer (multivariate-adjusted RR, 1.83 for BMI > or =30 kg/m2 vs. BMI <25 kg/m2; 95% CI, 0.90-3.72), and this association was stronger after exclusion of the first 2 years of follow-up (RR, 2.15; 95% CI, 1.05-4.40). In a multivariate analysis, waist-to-hip ratio was associated with ovarian cancer (RR, 1.59 for highest quartile vs. lowest quartile; 95% CI, 1.05-2.40), but a linear dose response was not found. An index that combined the frequency and intensity of leisure-time physical activity was associated positively with ovarian cancer incidence (multivariate-adjusted RR, 1.42 for high activity vs. low activity; 95% CI, 1.03-1.97). This association was particularly strong for frequency of vigorous physical activity (multivariate-adjusted RR, 2.38 for >4 times per week vs. rarely/never; 95% CI, 1.29-4.38). CONCLUSIONS: Anthropometric variables were not major risk factors for ovarian cancer in the cohort studied; however, high BMI in early adulthood and frequent and vigorous physical activity may increase the risk of ovarian cancer among postmenopausal women.     

Obesity, recreational physical activity, and risk of pancreatic cancer in a large U.S. Cohort.

BACKGROUND: Obesity and physical activity, in part through their effects on insulin sensitivity, may be modifiable risk factors for pancreatic cancer. METHODS: The authors analyzed data from the American Cancer Society Cancer Prevention Study II Nutrition Cohort to examine the association between measures of adiposity, recreational physical activity, and pancreatic cancer risk. Information on current weight and weight at age 18, location of weight gain, and recreational physical activity were obtained at baseline in 1992 via a self-administered questionnaire for 145,627 men and women who were cancer-free at enrollment. During the 7 years of follow-up, 242 incident pancreatic cancer cases were identified among these participants. Cox proportional hazards modeling was used to compute hazard rate ratios (RR) and to adjust for potential confounding factors including personal history of diabetes and smoking. RESULTS: We observed an increased risk of pancreatic cancer among obese [body mass index (BMI) >/= 30] men and women compared with men and women of normal BMI [<25; RR, 2.08; 95% confidence interval (95% CI), 1.48-2.93, P(trend) = 0.0001]. After adjustment for between BMI, risk of pancreatic cancer was independently increased among men and women who reported a tendency for central weight gain compared with men and women reporting a tendency for peripheral weight gain (RR, 1.45; 95% CI, 1.02-2.07). We observed no difference in pancreatic cancer incidence rates between men and women who were most active (>31.5 metabolic equivalent hours per week) at baseline compared with men and women who reported no recreational physical activity (RR, 1.20; 95% CI, 0.63-2.27). CONCLUSION: This study, along with several recent studies, supports the hypothesis that obesity and central adiposity are associated with pancreatic cancer risk.     

Height, body mass index, and ovarian cancer: a pooled analysis of 12 cohort studies.

BACKGROUND: Although many studies have investigated the association between anthropometry and ovarian cancer risk, results have been inconsistent. METHODS: The associations of height, body mass index (BMI), and ovarian cancer risk were examined in a pooled analysis of primary data from 12 prospective cohort studies from North America and Europe. The study population consisted of 531,583 women among whom 2,036 epithelial ovarian cancer cases were identified. To summarize associations, study-specific relative risks (RR) were estimated using the Cox proportional hazards model and then combined using a random-effects model. RESULTS: Women with height > or =1.70 m had a pooled multivariate RR of 1.38 [95% confidence interval (95% CI), 1.16-1.65] compared with those with height <1.60 m. For the same comparison, multivariate RRs were 1.79 (95% CI, 1.07-3.00) for premenopausal and 1.25 (95% CI, 1.04-1.49) for postmenopausal ovarian cancer (P(interaction) = 0.14). The multivariate RR for women with a BMI > or =30 kg/m(2) was 1.03 (95% CI, 0.86-1.22) compared with women with a BMI from 18.5 to 23 kg/m(2). For the same comparison, multivariate RRs were 1.72 (95% CI, 1.02-2.89) for premenopausal and 1.07 (95% CI, 0.87-1.33) for postmenopausal women (P(interaction) = 0.07). There was no statistically significant heterogeneity between studies with respect to height or BMI. BMI in early adulthood was not associated with ovarian cancer risk. CONCLUSION: Height was associated with an increased ovarian cancer risk, especially in premenopausal women. BMI was not associated with ovarian cancer risk in postmenopausal women but was positively associated with risk in premenopausal women.     

Carbohydrate intake, glycemic index and glycemic load in relation to risk of endometrial cancer: A prospective study of Swedish women

The associations of carbohydrate intake, glycemic index and glycemic load with endometrial cancer risk were examined among 61,226 participants of the Swedish Mammography Cohort who were cancer-free at enrollment between 1987 and 1990 and completed a food frequency questionnaire. During a mean follow-up of 15.6 years, through June 2005, 608 incident cases of endometrial adenocarcinoma were diagnosed. We observed no overall association between carbohydrate intake, glycemic index or glycemic load and incidence of endometrial cancer; the rate ratios (RRs) for the highest versus the lowest quintile were 1.12 (95% CI, 0.85-1.47) for carbohydrate intake, 1.00 (95% CI, 0.77-1.30) for glycemic index and 1.15 (95% CI, 0.88-1.51) for glycemic load. However, among obese women (body mass index, BMI > or =30 kg/m2), endometrial cancer incidence was nonsignificantly elevated in the top versus bottom quintiles of carbohydrate intake (RR, 1.68; 95% CI, 0.86-3.29) and glycemic load (RR, 1.57; 95% CI, 0.82-2.99). In a subanalysis of women who completed a follow-up questionnaire in 1997, which collected information on physical activity, carbohydrate intake and glycemic load were positively related to endometrial cancer risk among overweight women (BMI > or =25 kg/m2) with low physical activity. In this subgroup, the multivariate RRs comparing extreme quartiles were 1.90 (95% CI, 0.84-4.31) for carbohydrate intake and 2.99 (95% CI, 1.17-7.67) for glycemic load. Results from this cohort study suggest that a high carbohydrate intake and a high glycemic load may increase the risk of endometrial cancer among overweight women with low physical activity.     

Association of energy intake and energy balance with postmenopausal breast cancer in the prostate, lung, colorectal, and ovarian cancer screening trial.

Energy restriction remains one of the most effective ways known to prevent breast cancer in animal models. However, energy intake has not been consistently associated with risk of breast cancer in humans. In a prospective study, we assessed whether energy intake, body size, and physical activity each independently influence breast cancer risk in postmenopausal women and estimated the joint effect of combinations of these individual factors. As part of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, 38,660 women, ages 55 to 74 years and recruited from 10 centers in the United States during 1993 to 2001, were randomized to the screening arm of the trial. At baseline, the women completed a self-administered questionnaire, including a food frequency questionnaire. During follow-up from 1993 to 2003, 764 incident breast cancer cases were ascertained. Women in the highest quartile of energy intake (> or = 2,084 kcal/d) compared with those in the lowest quartile (<1,316 kcal/d) had a significantly increased risk for breast cancer [multivariate relative risk (RR), 1.25; 95% confidence interval (95% CI), 1.02-1.53; P(trend continuous) = 0.03]. Current body mass index (BMI) was also positively and significantly associated with risk (multivariate RR comparing >30 kg/m2 with <22.5 kg/m2, 1.35; 95% CI, 1.06-1.70; P(trend) = 0.01). Women with > or = 4 hours/wk of vigorous recreational physical activity had a significantly reduced risk of breast cancer compared with those who reported no recreational physical activity (multivariate RR, 0.78; 95% CI, 0.60-0.99; P(trend) = 0.15). None of these associations with individual energy balance measures was substantially confounded by the other two measures. When we estimated the joint effect of all three variables, women with the most unfavorable energy balance (the highest energy intake, highest BMI, and least physical activity) had twice the risk (RR, 2.10; 95% CI, 1.27-3.45) of women with the most favorable energy balance (the lowest energy intake, lowest BMI, and most physical activity). Although our estimates of absolute energy intake, based on a food frequency questionnaire, are imperfect, these results suggest that energy intake, in addition to BMI and physical activity may be independently associated with breast cancer risk. In addition, these three aspects of energy balance may act jointly in determining breast cancer risk.     

A pooled analysis of 14 cohort studies of anthropometric factors and pancreatic cancer risk

Epidemiologic studies of pancreatic cancer risk have reported null or nonsignificant positive associations for obesity, while associations for height have been null. Waist and hip circumference have been evaluated infrequently. A pooled analysis of 14 cohort studies on 846,340 individuals was conducted; 2,135 individuals were diagnosed with pancreatic cancer during follow-up. Study-specific relative risks (RRs) and 95% confidence intervals (CIs) were calculated by Cox proportional hazards models, and then pooled using a random effects model. Compared to individuals with a body mass index (BMI) at baseline between 21-22.9 kg/m(2) , pancreatic cancer risk was 47% higher (95%CI:23-75%) among obese (BMI ≥ 30 kg/m(2) ) individuals. A positive association was observed for BMI in early adulthood (pooled multivariate [MV]RR = 1.30, 95%CI = 1.09-1.56 comparing BMI ≥ 25 kg/m(2) to a BMI between 21 and 22.9 kg/m(2) ). Compared to individuals who were not overweight in early adulthood (BMI < 25 kg/m(2) ) and not obese at baseline (BMI < 30 kg/m(2) ), pancreatic cancer risk was 54% higher (95%CI = 24-93%) for those who were overweight in early adulthood and obese at baseline. We observed a 40% higher risk among individuals who had gained BMI ≥ 10 kg/m(2) between BMI at baseline and younger ages compared to individuals whose BMI remained stable. Results were either similar or slightly stronger among never smokers. A positive association was observed between waist to hip ratio (WHR) and pancreatic cancer risk (pooled MVRR = 1.35 comparing the highest versus lowest quartile, 95%CI = 1.03-1.78). BMI and WHR were positively associated with pancreatic cancer risk. Maintaining normal body weight may offer a feasible approach to reducing morbidity and mortality from pancreatic cancer.     

A prospective study of adiposity and postmenopausal breast cancer risk: the Malmö Diet and Cancer Study

High BMI is a well-known risk factor for postmenopausal breast cancer. There have been some reports of excess risk in association with weight gain and WHR, but little is known about the influence of body fatness per se. Using data from the Malm? Diet and Cancer Study, a prospective cohort study, 12,159 postmenopausal women (59.9 +/- 7.7 years) were categorized by quintiles of baseline anthropometric and impedance measures and reported weight change since age 20. RRs from multivariate Cox regression models were calculated. All analyses were adjusted for age, height, smoking, alcohol consumption, occupation, marital status, parity, age at first pregnancy, age at menarche and current hormone use. During the 5.7 years of follow-up, there were 246 incident breast cancer cases. Weight, height, BMI and %BF were positively associated with risk of breast cancer (p(trend) 21 kg (top quintile) had an RR of 1.75 (95% CI 1.11-2.77) compared to women with low weight gain. Breast cancer risk in postmenopausal women is predicted by increased body fat and weight gain. %BF is a more discriminating risk factor for breast cancer incidence than the commonly used BMI.     

Body mass index, weight change, and risk of prostate cancer in the Cancer Prevention Study II Nutrition Cohort.

BACKGROUND: Obesity has been associated with aggressive prostate cancer. The extent of this association, which varies by stage and grade, remains unclear. The role of recent weight change had not been previously examined. METHODS: We examined body mass index (BMI) and weight change in relation to incident prostate cancer by disease stage and grade at diagnosis among 69,991 men in the Cancer Prevention Study II Nutrition Cohort. Participants provided information on height and weight in 1982, and again at enrollment in 1992. During follow-up through June 30, 2003 (excluding the first 2 years of follow-up), we documented 5,252 incident prostate cancers. Cox proportional hazards models were used to estimate rate ratios (RR) and 95% confidence intervals (95% CI). RESULTS: The association between BMI in 1992 and risk of prostate cancer differed by stage and grade at diagnosis. BMI was inversely associated with risk of nonmetastatic low-grade prostate cancer (RR, 0.84; 95% CI, 0.66-1.06), but BMI was positively associated with risk of nonmetastatic high-grade prostate cancer (RR, 1.22; 95% CI, 0.96-1.55) and risk of metastatic or fatal prostate cancer (RR, 1.54; 95% CI, 1.06-2.23). Compared with weight maintenance, men who lost >11 pounds between 1982 and 1992 were at a decreased risk of nonmetastatic high-grade prostate cancer (RR, 0.58; 95% CI, 0.42-0.79). CONCLUSION: Obesity increases the risk of more aggressive prostate cancer and may decrease either the occurrence or the likelihood of diagnosis of less-aggressive tumors. Men who lose weight may reduce their risk of prostate cancer.     

Baseline recreational physical activity, history of sports participation, and postmenopausal breast carcinoma risk in the Netherlands Cohort Study.

BACKGROUND: The aim of the current study was to evaluate the relation between physical activity and breast carcinoma risk with specific emphasis on interaction with other aspects of energy balance. METHODS: The Netherlands Cohort Study on diet and cancer was conducted among 62,537 women ages 55-69 years at baseline. Information regarding baseline recreational physical activity, history of sports participation, and occupational physical activity was collected with a questionnaire in 1986. After 7.3 years of follow-up, 1208 incident breast carcinoma cases were available for case-cohort analyses. RESULTS: A summed total of baseline recreational physical activity (including walking, cycling, gardening) showed an inverse association with breast carcinoma risk. Women who were active in the above-mentioned activities for > 90 minutes a day had a rate ratio (RR) of 0.76 (95% confidence interval [95% CI], 0.58-0.99) compared with women who were active < 30 minutes a day. Women who ever participated into sports before baseline had a RR of 1.13 (95% CI, 0.94-1.37) compared with women who never participated in sports. The relation between sports participation and breast carcinoma risk did not appear to be dependent on the time window of participation (before/after menarche, before/after birth of the first child, before/after age 20 years). No interaction was found between baseline recreational physical activity, body mass index (BMI) (kg/m(2)), energy intake, and weight gain/loss during adult life in relation to breast carcinoma, although in the subgroup of women with a high BMI we found a stronger inverse relation between recreational physical activity and breast carcinoma risk independent of energy intake. Occupational physical activity was not found to be related to breast carcinoma risk. CONCLUSIONS: The current study findings support the hypothesis that recreational physical activity is associated inversely with breast carcinoma risk.     

Aspirin, NSAID, and acetaminophen use and the risk of endometrial cancer

To date, no prospective studies have explored the relationship between the use of aspirin, other nonsteroidal anti-inflammatory medications (NSAID), and acetaminophen and endometrial adenocarcinoma. Of the 82,971 women enrolled in a prospective cohort study, 747 developed medical record-confirmed invasive endometrial cancer over a 24-year period. Use of aspirin was ascertained from 1980 to 2004, and for other NSAIDs and acetaminophen, from 1990 to 2004. Cox regression models calculated multivariate relative risks (MV RR), controlling for body mass index (BMI), postmenopausal hormone (PMH) use, and other endometrial cancer risk factors. Currency, duration, and quantity of aspirin were not associated with endometrial cancer risk overall [current use: MV RR, 1.03; 95% confidence interval (CI) 0.83-1.27; >10 years of use: MV RR, 1.01; 95% CI, 0.78-1.30; and cumulative average >7 tablets per week: (MV RR, 1.10; 95% CI, 0.84-1.44)]. However, stratified analyses showed that a lower risk of endometrial cancer among obese (BMI, >or=30 kg/m(2)) women was seen with current aspirin use (MV RR, 0.66; 95% CI, 0.46-0.95). The greatest risk reduction for current aspirin users was seen in postmenopausal obese women who had never used PMH (MV RR, 0.43; 95% CI, 0.26-0.73). The use of other NSAIDs or acetaminophen was not associated with endometrial cancer. Our data suggest that use of aspirin or other NSAIDs does not play an important role in endometrial cancer risk overall. However, risk was significantly lower for current aspirin users who were obese or who were postmenopausal and had never used PMHs; these subgroup findings require further confirmation.     

Physical inactivity,energy intake,obesity and the risk of rectal cancer in Canada

We conducted a population-based case-control study of 1,447 incident rectal cancer cases and 3,106 population controls aged 20-76 years to assess the effect of recreational physical activity, energy intake and obesity on rectal cancer risk in 7 of 10 Canadian provinces in 1994-97. After adjustment for the effect of various potential confounding factors, total recreational physical activity in the highest quartile was associated with an odds ratio (OR) for rectal cancer risk of 0.88 (95% confidence interval [CI] = 0.64-1.20) in women and 1.15 (95% CI = 0.88-1.49) in men. Women and men in the highest quartile of caloric intake (> = 56,741 and > = 63,143 kJ/week) had ORs of 1.50 (95% CI = 1.00-2.25) and 1.61 (95% CI = 1.13-2.28), respectively. Total dietary fat intake was not associated with a risk of rectal cancer after adjustment for caloric intake. Obesity (BMI > = 30 kg/m(2)) was associated with an OR of 1.44 (95% CI = 1.06-1.95) for women and 1.78 (95% CI = 1.36-2.34) for men. Men and women with lifetime maximum body mass index (BMI) > = 30 kg/m(2) had respective ORs of 1.70 (95% CI = 1.30-2.23) and 1.26 (95% CI = 0.96-1.66). The greatest increase in rectal cancer risk was observed in men and women with simultaneous high energy intake, high BMI and low physical activity. Our study provides evidence that physical inactivity, high energy intake and obesity are associated with the risk of rectal cancer, and there is a probable synergic effect among the 3 risk factors.     

Body mass index, height, and the risk of ovarian cancer mortality in a prospective cohort of postmenopausal women.

Endogenous hormones may play a role in ovarian carcinogenesis. Postmenopausal obesity, although associated with higher circulating levels of estrogen and androgens, has not been linked consistently to ovarian cancer. The present study examined the relationship between body mass index (BMI), height, and ovarian cancer mortality among postmenopausal women in a large prospective mortality study of 300,537 women who were cancer free at enrollment in 1982 and had no history of hysterectomy or ovarian surgery. During 16 years of follow-up, 1,511 deaths occurred from ovarian cancer. Cox proportional hazard modeling was used to compute rate ratios (RRs) and to adjust for confounders. Ovarian cancer mortality rates were higher among overweight [BMI >/=25;RR, 1.16; 95% confidence interval (CI), 1.04-1.30] and obese women (BMI >/=30; RR, 1.26; 95% CI, 1.07-1.48) compared with women with BMI <25. Use of postmenopausal estrogens modified the association between BMI and ovarian cancer mortality (P = 0.05). The increased risk associated with obesity (BMI >/=30) was limited to women who never used postmenopausal estrogens (RR, 1.36; 95% CI, 1.12-1.66) and was not seen among ever users (RR, 0.93; 95% CI, 0.62-1.41). Height was positively associated with ovarian cancer mortality. Compared with women 152-156 cm tall, ovarian cancer mortality rates were lowest for the shortest women (RR, 0.72; 95% CI, 0.47-1.10 for women <152 cm) and highest for the tallest (RR, 1.41; 95% CI, 0.95-2.09 for women >/=177 cm). In this study, obesity and height appear to be independently associated with ovarian cancer mortality. The 36% increase in risk associated with obesity among women who had never used postmenopausal estrogens may have important public health implications because obesity is a growing problem in the United States.     

Vitamins C and E, retinol, beta-carotene and dietary fibre in relation to breast cancer risk: a prospective cohort study.

Association between breast cancer risk and the intake of vitamins C and E, retinol, beta (beta)-carotene, dietary fibre, vegetables, fruit and potatoes was examined in The Netherlands Cohort Study, for 62,573 women aged 55-69 years. After 4.3 years of follow-up, 650 incident breast cancer cases were identified. After adjusting for traditional risk factors, breast cancer risk was not influenced by the intake of beta-carotene, vitamin E, dietary fibre, supplements with vitamin C, vegetables or potatoes. Fruit consumption showed a non-significant inverse association with breast cancer risk (RR highest/lowest quintile = 0.76, 95% CI 0.54-1.08). A small reduction in risk was also observed with increasing intake of dietary vitamin C (RR highest/lowest quintile = 0.77, 95% CI 0.55-1.08). For retinol, a weak positive association was observed (RR highest/lowest quintile = 1.24, 95% CI 0.83-1.83). Among subjects with a high intake of polyunsaturated fatty acids (PUFAs), both beta-carotene and vitamin C intake showed a non-significant inverse association with breast cancer risk (P-trend = 0.15 and 0.16 respectively). Our findings do not suggest a strong role, if any, for intake of vitamins C and E, beta-carotene, retinol, dietary fibre, vegetables, fruit and potatoes in the aetiology of breast cancer.     

Prospective study of colorectal cancer risk and physical activity, diabetes, blood glucose and BMI: exploring the hyperinsulinaemia hypothesis

A sedentary lifestyle, obesity, and a Westernized diet have been implicated in the aetiology of both colorectal cancer and non-insulin dependent diabetes mellitus, leading to the hypothesis that hyperinsulinaemia may promote colorectal cancer. We prospectively examined the association between colorectal cancer risk and factors related to insulin resistance and hyperinsulinaemia, including BMI, physical activity, diabetes mellitus, and blood glucose, in a cohort of 75 219 Norwegian men and women. Information on incident cases of colorectal cancer was made available from the Norwegian Cancer Registry. Reported P values are two-sided. During 12 years of follow up, 730 cases of colorectal cancer were registered. In men, but not in women, we found a negative association with leisure-time physical activity (P for trend = 0.002), with an age-adjusted RR for the highest versus the lowest category of activity of 0.54 (95% CI = 0.37-0.79). Women, but not men, with a history of diabetes were at increased risk of colorectal cancer (age-adjusted RR = 1.55; 95% CI = 1.04-2.31), as were women with non-fasting blood glucose > or = 8.0 mmol l(-1)(age-adjusted RR = 1.98; 95% CI = 1.31-2.98) compared with glucose <8.0 mmol l(-1). Overall, we found no association between BMI and risk of colorectal cancer. Additional adjustment including each of the main variables, marital status, and educational attainment did not materially change the results. We conclude that the inverse association between leisure-time physical activity and colorectal cancer in men, and the positive association between diabetes, blood glucose, and colorectal cancer in women, at least in part, support the hypothesis that insulin may act as a tumour promoter in colorectal carcinogenesis.     

Physical activity and risk of breast cancer in premenopausal women

Physical activity appears to be inversely related to risk of breast cancer, yet the results remain inconsistent. To evaluate this relation among premenopausal women and examine variation in risk according to level of obesity and use of oral contraceptives (OCs), the authors examined data from the Nurses' Health Study II. During 10 years of follow-up, 849 cases of invasive premenopausal breast cancer were confirmed. Physical activity was assessed by self-report at baseline and during follow-up using a validated questionnaire. Total physical activity was unrelated to risk of breast cancer. Women engaging in >or=27 metabolic equivalent (MET)-h week(-1) had a multivariate-adjusted relative risk (RR) of 1.04 (95% confidence interval (CI) 0.82-1.33) compared to those in the <3 MET-h week(-1) category. Among women with a BMI >or=30 kg m(-2), we observed a significant positive dose-response relation (P=0.04). Activity was unrelated to breast cancer risk at lower levels of BMI. A test for interaction between activity and BMI (<30, >or=30 kg m(-2)) was statistically significant (P=0.02). Among current OC users, higher activity was associated with a non-significantly lower risk of breast cancer (RR=0.59, 95% CI 0.30-1.16 for >or=27 vs <9 MET-h week(-1), P for linear trend=0.14). These results show no overall association between physical activity and risk of breast cancer among premenopausal women, but suggest that the effect of physical activity could be substantially modified by the underlying degree of adiposity. The potential interactions between physical activity, adiposity, and current use of OCs require further study.     

The role of body weight in the relationship between physical activity and endometrial cancer: results from a large cohort of US women

Factors influencing circulating estrogen levels, insulin-mediated pathways or energy balance through obesity-related mechanisms, such as physical activity, have been proposed as potential risk factors for endometrial cancer. We examined measures of physical activity in relation to endometrial cancer risk in the American Cancer Society Cancer Prevention Study II Nutrition Cohort, a prospective study of cancer incidence and mortality, using information obtained at baseline in 1992. From 1992 to 2003, 466 incident endometrial cancers were identified among 42,672 postmenopausal women with intact uteri who were cancer-free at enrollment. Cox proportional hazards modeling was used to compute hazard rate ratios (RR) while adjusting for potential confounders. To assess the role of body mass index (BMI) in this relationship, we computed multivariate RR with and without adjustment for BMI and stratifying by BMI. All measures of physical activity and the avoidance of sedentary behavior were associated with lower endometrial cancer risk. Baseline recreational physical activity was associated with 33% lower risk (RR = 0.67, 95% CI 0.44-1.03 for 31.5+ vs. <7 MET-hr/week, trend p = 0.007) in the multivariate model without BMI. However, the trend was attenuated after further adjustment for BMI (trend p = 0.18). BMI significantly modified the association between physical activity and endometrial cancer risk (heterogeneity of trends p = 0.01). The inverse relationship was seen only among overweight or obese women (trend p = 0.003) and not in normal weight women (trend p = 0.51). In summary, light and moderate physical activity including daily life activities were associated with lower endometrial cancer risk in our study, especially among women who are overweight or obese.     

Physical activity and risk of colorectal cancer in men and women.

We examined the association between self-reported occupational and recreational physical activity and the subsequent risk of colorectal cancer in a population-based cohort in Norway. During a mean follow-up time of 16.3 years for males and 15.5 years for females, 236 and 99 colon cancers and 170 and 58 rectal cancers were observed in males and females, respectively, among 53,242 males and 28,274 females who attended the screening between 1972 and 1978. Physical activity at a level equivalent to walking or bicycling for at least four hours a week during leisure-time was associated with decreased risk of colon cancer among females when compared with the sedentary group (RR = 0.62, 95% CI 0.40-0.97). Reduced risk of colon cancer was particularly marked in the proximal colon (RR = 0.51, 95% CI 0.28-0.93). This effect was not observed for occupational physical activity alone, probably due to a narrow range of self-reported physical activity at work among females. However, by combining occupational and recreational physical activity we observed an inverse dose-response effect as increasing total activity significantly reduced colon cancer risk (P for trend = 0.04). Among males 45 years or older at entry to the study, an inverse dose-response effect was observed between total physical activity and colon cancer risk (P for trend = 0.04). We also found in males a stronger preventive effect for physical activity in the proximal as compared to distal colon. In addition, we found a borderline significant decrease in colon cancer risk for occupational physical activity in males 45 years or older when compared to the sedentary group (RR = 0.74, 95% CI 0.53-1.04). All results were adjusted for age, body mass index, serum cholesterol and geographic region. No association between physical activity and rectal cancer was observed in males or females. The protective effect of physical activity on colon cancer risk is discussed in regard to energy balance, dietary factors, age, social class, body mass index and gastrointestinal transit time.     

A prospective study of fish, marine fatty acids, and bladder cancer risk among men and women (United States)

Objective To evaluate prospectively the association between intakes of fish, marine fatty acids, and bladder cancer risk in two ongoing cohorts, the Health Professionals Follow-up Study and the Nurses’ Health Study. Methods During 16 and 18 years of follow-up, 501 and 235 incident cases of bladder cancer were diagnosed among men and women, respectively. Cox proportional hazard models were used to estimate incidence rate ratios (RR) and 95% confidence intervals (CI) between fish intake and bladder cancer risk adjusting for age, total caloric intake, pack-years of cigarette smoking, and current smoking. Results We observed no significant overall association between total fish intake and bladder cancer risk, even when we compared ≥1 servings of fish per day to fish intake ≤1–3 servings per month. Among men, a statistically significant lower risk of bladder cancer was observed among men consuming fish or high marine fatty acid, after excluding the first 4 years of follow-up (MV RR = 0.60; 95% CI, 0.38–0.94, for ≥1 total fish servings per day compared to ≤1–3 servings per month). Conclusions Overall, these findings suggest that fish intake is not likely to be appreciably associated with the risk of bladder cancer.     

Anthropometry, physical activity, and endometrial cancer risk: results from the Netherlands Cohort Study

Although obesity is an established risk factor for endometrial cancer, evidence linking risk to height, weight change since age 20, and physical activity is limited. In this case-cohort study, 62 573 women from The Netherlands Cohort Study on Diet and Cancer were followed up from 1986 to 1995, and 226 endometrial cancer case patients were identified. In Cox proportional hazards analyses, women 175 cm or taller had an increased risk of endometrial cancer compared with those less than 160 cm (rate ratio [RR] = 2.57, 95% confidence interval [CI] = 1.32 to 4.99). Compared with women with a body mass index (BMI; kg/m2) between 20 and 22.9, women with a BMI of 30 or greater had a higher risk (RR = 4.50, 95% CI = 2.62 to 7.72; P(trend)<.001). Moreover, BMI at age 20 and BMI gain since age 20 were positively associated with endometrial cancer risk (P(trend) = .02 and <.001, respectively). Women who spent 90 minutes per day or more doing nonoccupational physical activities had a lower risk (RR = 0.54, 95% CI = 0.34 to 0.85; P(trend) = .002) compared with those who spent less than 30 minutes per day. High BMI and low physical activity were strong and independent risk factors for endometrial cancer.     

Body size and risk of renal cell carcinoma in the European Prospective Investigation into Cancer and Nutrition (EPIC)

Previous studies suggest that obesity is related to increased risk of renal cell carcinoma (RCC); however, only a few studies report on measures of central vs. peripheral adiposity. We examined the association between anthropometric measures, including waist and hip circumference and RCC risk among 348,550 men and women free of cancer at baseline from 8 countries of the European Prospective Investigation into Cancer and Nutrition (EPIC). During 6.0 years of follow-up we identified 287 incident cases of RCC. Relative risks were calculated using Cox regression, stratified by age and study center and adjusted for smoking status, education, alcohol consumption, physical activity, menopausal status, and hormone replacement therapy use. Among women, an increased risk of RCC was conferred by body weight (relative risk [RR] in highest vs. lowest quintile = 2.13; 95% confidence interval [CI] = 1.16-3.90; p-trend = 0.003), body mass index (BMI) (RR = 2.25; 95% CI = 1.14-4.44; p-trend = 0.009), and waist (RR = 1.67; 95% CI = 0.94-2.98; p-trend = 0.003) and hip circumference (RR = 2.30; 95% CI = 1.22-4.34; p-trend = 0.01); however, waist and hip circumference were no longer significant after controlling for body weight. Among men, hip circumference (RR = 0.44; 95% CI = 0.20-0.98; p-trend = 0.03) was related significantly to decreased RCC risk only after accounting for body weight. Height was not related significantly to RCC risk. Our findings suggest that obesity is related to increased risk of RCC irrespective of fat distribution among women, whereas low hip circumference is related to increased RCC risk among men. Our data give further credence to public health efforts aiming to reduce the prevalence of obesity to prevent RCC, in addition to other chronic diseases.