Biomedical subjects
Publications and source records attributed to A Wolk.
In a prospective cohort study of 74 250 Swedish women and men, with 7.2 years of follow-up and 705 incident colorectal cancer cases, long duration of aspirin use (>20 years) was associated with a reduced risk of colorectal cancer (multivariate rate ratio: 0.65; 95% confidence interval: 0.45-0.94). Aspirin use for a shorter period was not associated with risk.
AIMS/HYPOTHESIS: Epidemiological evidence indicates that individuals with diabetes mellitus have an increased risk of several cancers. We performed a systematic review with meta-analysis to evaluate the association between diabetes and risk of bladder cancer. METHODS: Pertinent studies were identified by searching MEDLINE (from January 1966 to July 2006) and by reviewing the reference lists of retrieved articles. We included case-control and cohort studies reporting relative risk (RR) estimates with 95% CIs (or data to calculate them) of bladder cancer associated with diabetes. Studies of type 1 diabetes were not included. Summary RRs were calculated using a random-effects model. RESULTS: A total of 16 studies (seven case-control studies, three cohort studies and six cohort studies of diabetic patients) fulfilled the inclusion criteria. Analysis of all studies showed that diabetes was associated with an increased risk of bladder cancer, compared with no diabetes (RR = 1.24, 95% CI 1.08-1.42). There was strong evidence of heterogeneity among these studies (p < 0.0001). Stratification by study design found that diabetes was associated with an increased risk of bladder cancer in case-control studies (RR = 1.37, 95% CI 1.04-1.80, p (heterogeneity) = 0.005) and cohort studies (RR = 1.43, 95% CI 1.18-1.74, p (heterogeneity) = 0.17), but not in cohort studies of diabetic patients (RR = 1.01, 95% CI 0.91-1.12, p (heterogeneity) = 0.35). CONCLUSIONS/INTERPRETATION: Findings from this meta-analysis suggest that individuals with diabetes may have a modestly increased risk of bladder cancer.
INTRODUCTION: Consumption of coffee and tea, and total intake of caffeine has been claimed to be associated with osteoporotic fracture risk. However, results of earlier studies lack consistency. METHODS: We examined this relation in a cohort of 31,527 Swedish women aged 40-76 years at baseline in 1988. The consumption of coffee, caffeinated tea and the intake of caffeine were estimated from a self-administered food frequency questionnaire (FFQ). Multivariate-adjusted hazards ratios (HRs) of fractures with 95% confidence intervals (95% CIs) were estimated by Cox proportional hazards models. RESULTS: During a mean follow-up of 10.3 years, we observed 3,279 cases with osteoporotic fractures. The highest (>330 mg/day) compared with the lowest (<200 mg/day) quintile of caffeine intake was associated with a modestly increased risk of fracture: HR 1.20 (95% CI: 1.07-1.35). A high coffee consumption significantly increased the risk of fracture (p for trend 0.002), whereas tea drinking was not associated with risk. The increased risk of fracture with both a high caffeine intake and coffee consumption was confined to women with a low calcium intake (<700 mg/day): HR 1.33 (95% CI: 1.07-1.65) with > or =4 cups (600 ml)/day of coffee compared to <1 cup (150 ml)/day. The same comparison but risk estimated for women with a high propensity for fractures (> or =2 fracture types) revealed a HR of 1.88 (95% CI: 1.17-3.00). CONCLUSIONS: In conclusion, our results indicate that a daily intake of 330 mg of caffeine, equivalent to 4 cups (600 ml) of coffee, or more may be associated with a modestly increased risk of osteoporotic fractures, especially in women with a low intake of calcium.
Alcohol has been hypothesized to promote ovarian carcinogenesis by its potential to increase circulating levels of estrogen and other hormones; through its oxidation byproduct, acetaldehyde, which may act as a cocarcinogen; and by depletion of folate and other nutrients. Case-control and cohort studies have reported conflicting results relating alcohol intake to ovarian cancer risk. We conducted a pooled analysis of the primary data from ten prospective cohort studies. The analysis included 529 638 women among whom 2001 incident epithelial ovarian cases were documented. After study-specific relative risks (RR) and 95% confidence intervals (CI) were calculated by Cox proportional hazards models, and then were pooled using a random effects model; no associations were observed for intakes of total alcohol (pooled multivariate RR=1.12, 95% CI 0.86-1.44 comparing > or =30 to 0 g day(-1) of alcohol) or alcohol from wine, beer or spirits and ovarian cancer risk. The association with alcohol consumption was not modified by oral contraceptive use, hormone replacement therapy, parity, menopausal status, folate intake, body mass index, or smoking. Associations for endometrioid, mucinous, and serous ovarian cancer were similar to the overall findings. This pooled analysis does not support an association between moderate alcohol intake and ovarian cancer risk.
We examined the associations of body mass index (BMI), waist circumference, a history of diabetes, and cigarette smoking with risk of pancreatic cancer among 37,147 women and 45,906 men followed up during 560,666 person-years in the Swedish Mammography Cohort and the Cohort of Swedish Men; 136 incident cases of pancreatic cancer were diagnosed. The multivariate rate ratio (RR) of pancreatic cancer for obese women and men (BMI > or =30 kg/m(2)) was 1.81 (95% CI: 1.04-3.15) compared to those with a BMI of 20-25 kg/m(2). For a difference of 20 cm (about two standard deviations) in waist circumference, the multivariate RRs were 1.32 (95% CI: 0.73-2.37) among women and 1.74 (95% CI: 1.00-3.01) among men. Pancreatic cancer risk was associated with history of diabetes (multivariate RR: 1.88; 95% CI: 1.09-3.26) and cigarette smoking (multivariate RR for current compared with never smokers: 3.06; 95% CI: 1.99-4.72). Current smokers of > or =40 pack-years had a five-fold elevated risk compared with never smokers. Risk among past smokers approached the RR for never smokers within 5-10 years following smoking cessation. Findings from this prospective study support positive relationships of overall obesity, abdominal adiposity, diabetes and smoking with risk of pancreatic cancer.
We examined prospectively the association between whole grain consumption and colorectal cancer risk in the population-based Swedish Mammography Cohort. A total of 61,433 women completed a food-frequency questionnaire at baseline (1987-1990) and, through linkage with the Swedish Cancer Registry, 805 incident cases of colorectal cancer were identified during a mean follow-up of 14.8 years. High consumption of whole grains was associated with a lower risk of colon cancer, but not of rectal cancer. The multivariate rate ratio (RR) of colon cancer for the top category of whole grain consumption (> or = 4.5 servings day(-1)) compared with the bottom category (<1.5 servings day(-1)) was 0.67 (95% confidence interval (CI), 0.47-0.96; P-value for trend=0.06). The corresponding RR after excluding cases occurring within the first 2 years of follow-up was 0.65 (95% CI, 0.45-0.94; P-value for trend=0.04). Our findings suggest that high consumption of whole grains may decrease the risk of colon cancer in women.
OBJECTIVE: To examine whether early anthropometric measures and reproductive factors were associated with body mass index (BMI), overweight, and obesity. DESIGN: Cross-sectional, observational study. SUBJECTS: In all, 18 109 healthy women who participated in the Swedish Mammography Cohort aged 49-83 y. MEASUREMENTS: Early anthropometric (birthweight and body shape at age 10 y) and reproductive (age at menarche, age at the birth of the first child, and parity) variables were our predictors and current BMI, overweight (BMI 25-29.99 kg/m(2)), and obesity (BMI > or =30 kg/m(2)) were our outcomes. RESULTS: In multivariate-adjusted polytomous logistic regression analysis, risk of overweight and obesity increased with increasing body shape at age 10 y and decreased with increasing age at menarche and age at first birth (P for trend <0.0001). A U-shaped relation with birthweight was observed. In our tests for effect modification of the relation with overweight/obesity (ow/ob; BMI > or =25 kg/m(2)), we detected significant interactions between body shape at 10 y and age (P<0.0001); body shape at 10 y and physical activity (P<0.0001); age at first birth and smoking (P=0.02); and parity and physical activity (P=0.004). The increased risk of ow/ob among women who reported a larger childhood body shape was reduced as women moved from the lowest to highest quartile of physical activity in adulthood. Likewise, the increasing risk of ow/ob among women with greater parity was reduced with increased physical activity. CONCLUSION: Early anthropometric measures and reproductive factors are significantly associated with BMI, overweight, and obesity among older women. The effects of childhood body weight, age at first birth, and parity may be modified by adult lifestyle choices, as well as age.
We prospectively examined the incidence of epithelial ovarian cancer and its subtypes in relation to baseline fruit and vegetable consumption in the Swedish Mammography Cohort, a population-based cohort study of 61 084 women aged 38-76 years in 1987-1990. During an average follow-up of 13.5 years, 266 incident cases of invasive epithelial ovarian cancer were diagnosed. After adjustment for potential confounders, we observed a statistically significant inverse association between consumption of vegetables and ovarian cancer risk (P-value for trend=0.01); the multivariate rate ratio (RR) for the comparison of three or more servings of vegetables per day with one or fewer servings per day was 0.61 (95% confidence interval (CI), 0.38-0.97). For fruit consumption a modest, not statistically significant, positive association was found (P-value for trend=0.07); the multivariate RR for the highest compared with the lowest category of consumption being 1.37 (95% CI, 0.90-2.06). The associations with fruit and vegetable consumption did not vary by subtype of ovarian cancer. These findings suggest that high consumption of vegetables, but not of fruits, may reduce the risk of ovarian cancer.
OBJECTIVE: To evaluate the sensitivity and specificity of a self-administered food frequency questionnaire (FFQ)-used in a cohort of 48,000 men to determine dietary supplement use. DESIGN: Questionnaire data regarding use of dietary supplements were compared with 14 24-h recall interviews spread over a year. SETTING AND SUBJECTS: A random sample of 248 middle-aged and elderly Swedish men was included in the analysis. RESULTS AND CONCLUSIONS: Use of any supplement in at least one interview was reported by 51% (in three or more interviews by 38%). Sensitivity and specificity of the FFQ regarding any supplement use was 78 and 93%, respectively. Sensitivity for multivitamins, vitamins C and E was 69, 67 and 78%, respectively. The sensitivity increased to 93% and the specificity decreased to 88% when a user was defined as a person reporting use in at least three interviews. CONCLUSIONS: Dietary supplement use might be measured by a self-administered questionnaire relatively well especially when supplements are used more regularly.
We investigated effects of occupational physical activity on relative risk for prostate cancer. From Swedish nationwide censuses in 1960 and 1970, we defined two cohorts of men whose occupational titles allowed classification of physical activity levels at work in 1960 (n=1,348,971) and in 1970 (n=1,377,629). A third cohort included only men whose jobs required a similar level of physical activity in both 1960 and 1970 (n=673,443). The incidence of prostate cancer between 1971 and 1989 was ascertained through record linkage to the Swedish Cancer Register. A total of 43,836, 28,702, and 19,670 prostate cancers, respectively, occurred in the three cohorts. In all three cohorts, the relative risk for prostate cancer increased with decreasing level of occupational physical activity (P<0.001), using Poisson regression. Among men with the same physical activity levels in 1960 and 1970, the rate ratio was 1.11 for men with sedentary jobs as compared with those whose jobs had very high/high activity levels after adjustment for age at follow-up, calendar year of follow-up and place of residence (95% CI 1.05-1.17; P for trend <0.001). There was no association between occupational activity and prostate cancer mortality. Since we had no data on other potential risk factors the observed associations for both incidence and mortality might have been confounded. Further studies are needed to better understand the potential role of physical activity for prostate cancer.
BACKGROUND: Despite a large public health interest in physical activity and its role in obesity and other chronic diseases, only a few reports to date have addressed total levels of physical activity in relation to age, body mass, health and other lifestyle factors. OBJECTIVE: To investigate whether levels of total physical activity among men are associated with age, body mass, self-rated health and other lifestyle factors in a cross-sectional setting. METHODS: In a population-based cohort of 33 466 men aged 45-79 y in central Sweden, we collected information about physical activity through a self-administered questionnaire. Level of total physical activity was assessed quantitatively based on six questions on different activities: work/occupation, housework, walking/bicycling, exercise, inactive leisure time and sleeping. The physical activity levels were measured as metabolic equivalents, MET-h/day. The relation between age, body mass index, smoking, education, marital status and self-rated health, and total physical activity was studied in a cross-sectional analysis, using multivariate regression. RESULTS: Total daily physical activity was decreasing systematically between age 45 and 79 (-4.1%, 95% CI -4.6, -3.6). Obese men reported -2.6% (95% CI -3.0, -2.1) lower physical activity than normal weight men. Those with high education had -7.0% (95%CI -7.3, -6.7) lower total physical activity than those with elementary school. Men with self-rated poor health had -11.3% (95%CI -12.1, -10.6) lower physical activity than those reporting very good health. The cross-sectionally observed decrease with age was greatest among obese men (-8.7%), current smokers (-7.9%), low-educated men (-5.6%) and those with poor health (-9.8%); the subgroups with very good health reported almost the same level of total physical activity (-0.6%) for age 74-79 as for age 45-49. CONCLUSIONS: The observed decreasing levels of total physical activity with age to large degree depend on health status and other factors. The characterization of subjects with low total physical activity levels is of importance for understanding observed worldwide trends in increasing prevalence of obesity. The better understanding of these phenomena might also facilitate a better planning of public health interventions with messages specifically adjusted for subgroups of population with lower physical activity.
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A number of prospective cohort studies have examined the relations of individual dietary variables to risk of colorectal cancer. Few studies have addressed the broader eating patterns that reflect many dietary exposures working together. Using data from a prospective study of 61,463 women, with an average follow-up period of 9.6 years (between 1987 and 1998) and 460 incident cases of colorectal cancer, the authors conducted a factor analysis to identify and examine major dietary patterns in relation to colorectal cancer risk. Using proportional hazards regression to estimate relative risks, the authors found no clear association between a "Western," "healthy," or "drinker" dietary pattern and colorectal cancer risk. However, the data suggested that consuming low amounts of foods that constitute a "healthy" dietary pattern may be associated with increased risks of colon and rectal cancers. An inverse association with the "healthy" dietary pattern was found among women under age 50 years, although the number of cancers in this age group was limited and interpretation of this finding should be cautious. In this age group, relative risks for women in increasing quintiles of the "healthy" dietary pattern, compared with the lowest quintile, were 0.74 (95% confidence interval (CI): 0.41, 1.31), 0.69 (95% CI: 0.39, 1.24), 0.59 (95% CI: 0.32, 1.07), and 0.45 (95% CI: 0.23, 0.88) (p for trend = 0.03). The role of overall eating patterns in predicting colorectal cancer risk requires further investigation.
Obesity has been associated with an increased risk of renal cell cancer among women, while the evidence for men is considered weaker. We conducted a quantitative summary analysis to evaluate the existing evidence that obesity increases the risk of renal cell cancer both among men and women. We identified all studies examining body weight in relation to kidney cancer, available in MEDLINE from 1966 to 1998. The quantitative summary analysis was limited to studies assessing obesity as body mass index (BMI, kg m(-2)), or equivalent. The risk estimates and the confidence intervals were extracted from the individual studies, and a mixed effect weighted regression model was used. We identified 22 unique studies on each sex, and the quantitative analysis included 14 studies on men and women, respectively. The summary relative risk estimate was 1.07 (95% CI 1.05-1.09) per unit of increase in BMI (corresponding to 3 kg body weight increase for a subject of average height). We found no evidence of effect modification by sex. Our quantitative summary shows that increased BMI is equally strongly associated with an increased risk of renal cell cancer among men and women.
The relation between relative body weight and colorectal cancer among women is unclear. In a large prospective cohort study, we found a positive association only for distal cancers among younger women that became attenuated at older ages. These results support previous reports in which results were stratified by age or colorectal cancer site.
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Consumption of fatty fish might reduce the risk of prostate cancer, although epidemiological studies of fish consumption are rare. We studied the association between fish consumption and prostate cancer in a population-based prospective cohort of 6272 Swedish men. During 30 years of follow-up, men who ate no fish had a two-fold to three-fold higher frequency of prostate cancer than those who ate moderate or high amounts did. Our results suggest that fish consumption could be associated with decreased risk of prostate cancer.
Recently, there has been interest in whether intakes of specific types of fat are associated with breast cancer risk independently of other types of fat, but results have been inconsistent. We identified 8 prospective studies that met predefined criteria and analyzed their primary data using a standardized approach. Holding total energy intake constant, we calculated relative risks for increments of 5% of energy for each type of fat compared with an equivalent amount of energy from carbohydrates or from other types of fat. We combined study-specific relative risks using a random effects model. In the pooled database, 7,329 incident invasive breast cancer cases occurred among 351,821 women. The pooled relative risks (95% confidence intervals [CI]) for an increment of 5% of energy were 1.09 (1.00-1.19) for saturated, 0.93 (0.84-1.03) for monounsaturated and 1.05 (0.96-1.16) for polyunsaturated fat compared with equivalent energy intake from carbohydrates. For a 5% of energy increment, the relative risks were 1.18 (95% CI 0.99-1.42) for substituting saturated for monounsaturated fat, 0.98 (95% CI 0.85-1.12) for substituting saturated for polyunsaturated fat and 0.87 (95% CI 0.73-1.02) for substituting monounsaturated for polyunsaturated fat. No associations were observed for animal or vegetable fat intakes. These associations were not modified by menopausal status. These data are suggestive of only a weak positive association with substitution of saturated fat for carbohydrate consumption; none of the other types of fat examined was significantly associated with breast cancer risk relative to an equivalent reduction in carbohydrate consumption.