A prospective study of occupation and prostate cancer risk

A wide variety of occupations has been associated with prostate cancer in previous retrospective studies. Most attention has been paid to farming, metal working, and the rubber industry. Today, these results cannot be affirmed with confidence, because many associations could be influenced by recall bias, have been inconsistent, or have not been confirmed satisfactory in subsequent studies. This study was conducted to investigate and confirm these important associations in a large prospective cohort study. The authors conducted a prospective cohort study among 58,279 men. In September 1986, the cohort members (55-69 years) completed a self-administered questionnaire on potential cancer risk factors, including job history. Related job codes were clustered in professional groups. These predefined clusters were investigated in 3 time windows: 1) profession ever performed, 2) longest profession ever held, and 3) last profession held at baseline. Follow up for incident prostate cancer was established by linkage to cancer registries until December 1993. A case-cohort approach was used based on 830 cases and 1525 subcohort members. To minimize false-positive results, 99% confidence intervals (99% CI) were calculated. Although moderately decreased prostate cancer risks were found for electricians, farmers, firefighters, woodworkers, textile workers, butchers, salesmen, teachers, and clerical workers, none of the relative risks (RR) were found to be statistically significant. For road transporters, metal workers, and managers, no association with prostate cancer risk was found. Although the RR for railway workers, mechanics, welders, chemists, painters, and cooks was moderately increased, these estimates were not statistically significant. For men who reported to have ever worked in the rubber industry, we found a substantially increased prostate cancer risk, but not statistically significant (RR, 4.18; 99% CI = 0.22-80.45). For policemen, we found a substantial and marginally statistically significant increased prostate cancer risk, especially for those who reported working as a policeman for most of their occupational life (RR, 3.91; 99% CI = 1.14-13.42) or as the last profession held at baseline (RR, 4.00; 99% CI = 1.19-13.37). Most of the previously investigated associations between occupation and prostate cancer risk could not be confirmed with confidence in this prospective study. The lack of statistical significance for rubber workers could be caused by the scarcity of rubber workers in this cohort and subsequent lack of power. The results for policemen were substantial and statistically significant, although a conservative value for significance level was used.     

Alcohol intake, drinking patterns, and risk of prostate cancer in a large prospective cohort study

Alcohol drinking has been extensively studied in relation to prostate cancer, yet findings on the direction of the association are equivocal. Previous studies have not examined drinking patterns. Thus, the authors prospectively evaluated the associations between these factors and risk of incident prostate cancer (n = 2,479) in a cohort study of 47,843 US men (1986-1998). The men completed a questionnaire at baseline that included information on consumption of specific types of alcohol and frequency of use. The authors estimated hazard ratios using Cox proportional hazards regression for average alcohol intake and number of days per week on which alcohol was consumed stratified by average weekly intake (<105 g/week vs. > or = 105 g/week). Compared with nondrinking, the hazard ratio for consumption increased slightly from an average of 5.0-14.9 g/day (hazard ratio (HR) = 1.05, 95% confidence interval (CI): 0.94, 1.18) to 30.0-49.9 g/day (HR = 1.13, 95% CI: 0.96, 1.33), but it was not increased at > or = 50 g/day (HR = 1.00, 95% CI: 0.77, 1.31) after adjustment for recent smoking and other factors. Compared with abstainers, risk was greatest among men who consumed an average of > or = 105 g/week but who drank on only 1-2 days per week (HR = 1.64, 95% CI: 1.13, 2.38). These results suggest that moderate or greater alcohol consumption is not a strong contributor to prostate cancer risk, except possibly in men who consume large amounts infrequently.     

A cohort study of farming and risk of prostate cancer in Iowa.

Although farming has been linked to prostate cancer mortality, few investigations have addressed its association with prostate cancer incidence. We followed a population-based cohort of 1,177 cancer-free men for up to 9 years and identified 81 incident prostate cancers. Men whose usual occupation was farmer were at an increased risk of prostate cancer after adjustment for age, smoking, alcohol, and dietary factors (RR = 1.7; 95% CI = 1.0-2.7). Exclusion of well-differentiated, localized tumors slightly strengthened the association (RR = 2.0; 95% CI = 1.1-3.6). Risk was confined to older (age 70+ years) farmers (RR = 2.2; 95% CI = 1.1-4.3); we found no evidence of an effect among younger farmers (RR = 1.0; 95% CI = 0.4-2.1).     

Oxidative balance score and risk for incident prostate cancer in a prospective U.S. cohort study

PurposeOxidative stress is defined as an imbalance between pro-oxidants and antioxidants. Previous research found that a single comprehensive oxidative balance score (OBS) that includes individual pro- and anti-oxidant exposures may be associated with various conditions (including prostate cancer) in the absence of associations with the individual factors. We investigated an OBS-incident prostate cancer association among 43,325 men in the Cancer Prevention Study II Nutrition Cohort.MethodsFrom 1999–2007, 3386 incident cases were identified. Twenty different components, used in two ways (unweighted or weighted based on literature reviews), were incorporated into the OBS, and the resulting scores were then expressed as three types of variables (continuous, quartiles, or six equal intervals). Multivariable-adjusted rate ratios were calculated using Cox proportional hazards models.ResultsWe hypothesized that the OBS would be inversely associated with prostate cancer risk; however, the rate ratios (95% confidence intervals) comparing the highest with the lowest OBS categories ranged from 1.17 (1.04–1.32) to 1.39 (0.90–2.15) for all cases, 1.14 (0.87–1.50) to 1.59 (0.57–4.40) for aggressive disease (American Joint Committee on Cancer stage III/IV or Gleason score 8–10), and 0.91 (0.62–1.35) to 1.02 (1.02–1.04) for nonaggressive disease.ConclusionsOur findings are not consistent with the hypothesis that oxidative balance–related exposures collectively affect risk for prostate cancer.     

Diabetes and risk of prostate cancer in a prospective cohort of US men

One previous study has suggested that diabetes may decrease risk of prostate cancer but only several years after diagnosis of diabetes. The authors examined the role of timing of diabetes diagnosis in relation to risk of prostate cancer among men in the Cancer Prevention Study II Nutrition Cohort. Participants in the study completed a mailed questionnaire including information on diabetes at enrollment in 1992 and at follow-up questionnaires in 1997 and 1999. Historical information on diabetes was also available from a previous study in 1982. The authors documented 5,318 cases of incident prostate cancer through August 31, 2001, among 72,670 men. Results from Cox proportional hazards models showed that diabetes was associated with a lower incidence of prostate cancer (rate ratio (RR) = 0.67, 95% confidence interval (CI): 0.60, 0.75). This association differed significantly by time since diagnosis of diabetes (p < 0.0002); risk of prostate cancer was slightly increased during the first 3 years after diagnosis of diabetes (RR = 1.23, 95% CI: 0.92, 1.65) but was reduced among men diagnosed 4 or more years before (RR = 0.63, 95% CI: 0.56, 0.71). Study results are consistent with the hypothesis that diabetes is associated with reduced risk of prostate cancer but only several years after diagnosis of diabetes.     

Vitamin A, retinol, and carotenoids and the risk of gastric cancer: a prospective cohort study

BACKGROUND: Vitamin A may influence gastric carcinogenesis through its essential role in controlling cell proliferation and differentiation. However, epidemiologic studies of vitamin A, retinol (preformed vitamin A), and provitamin A carotenoids in relation to the risk of gastric cancer have documented inconsistent results. OBJECTIVE: The objective of the study was to examine the associations between intakes of vitamin A, retinol, and specific carotenoids and the risk of gastric cancer in a prospective population-based cohort study of Swedish adults. DESIGN: The study cohort consisted of 82 002 Swedish adults aged 45-83 y who had completed a food-frequency questionnaire in 1997. The participants were followed through June 2005. RESULTS: During a mean 7.2-y follow-up, 139 incident cases of gastric cancer were diagnosed. High intakes of vitamin A and retinol from foods only (dietary intake) and from foods and supplements combined (total intake) and of dietary alpha-carotene and beta-carotene were associated with a lower risk of gastric cancer. The multivariate relative risks for the highest versus lowest quartiles of intake were 0.53 (95% CI: 0.32, 0.89; P for trend = 0.02) for total vitamin A, 0.56 (95% CI: 0.33, 0.95; P for trend = 0.05) for total retinol, 0.50 (95% CI: 0.30, 0.83; P for trend = 0.03) for alpha-carotene, and 0.55 (95% CI: 0.32, 0.94; P for trend = 0.07) for beta-carotene. No significant associations were found for beta-cryptoxanthin, lutein and zeaxanthin, or lycopene intake. CONCLUSION: High intakes of vitamin A, retinol, and provitamin A carotenoids may reduce the risk of gastric cancer.     

A prospective study of physical activity and risk of prostate cancer in US physicians

BACKGROUND: Exercise can suppress androgen production and may thus decrease the risk of prostate cancer. However, findings from epidemiological studies assessing physical activity and risk of prostate cancer are inconsistent. METHODS: We prospectively examined the association between physical activity and prostate cancer risk in the Physicians' Health Study (PHS), a randomized trial of low-dose aspirin and beta-carotene among 22,071 men aged 40-84 without self-reported myocardial infarction, stroke and cancer. At baseline in 1982, men were asked about the frequency of exercise vigorous enough to work up a sweat. Physical activity was assessed in a similar fashion again at 36 months of follow-up. RESULTS: During 11.1 years of follow-up (258 779 person-years), 982 cases of prostate cancer occurred and were confirmed by medical record review. After adjustment for potential confounding factors (including age, height, randomized treatment assignment, smoking status, alcohol intake, use of multivitamins, history of diabetes, history of hypertension and history of high cholesterol), the relative risks for prostate cancer associated with exercise vigorous enough to work up a sweat were 1.0 (referent) for frequency less than once per week, 1.02 (95% CI: 0.82-1.26) for once per week, 1.07 (95% CI: 0.90-1.27) for 2-4 times per week, and 1.11 (95% CI: 0.90-1.36) for 5+ times per week. Across all subgroups of men categorized by age, body mass index, smoking status, alcohol intake, use of multivitamins, history of diabetes, history of hypertension and history of high cholesterol, there were no significant associations between frequency of exercise vigorous enough to work up a sweat and prostate cancer risk. After excluding cases of prostate cancer that occurred during the first 36 months of follow-up, again, there was no significant association. Combining physical activity assessments at baseline and at 36 months also yielded no significant association with prostate cancer risk. CONCLUSIONS: These observational data from the Physicians' Health Study do not support the hypothesis that increased physical activity reduces the risk of prostate cancer.     

A prospective study of iodine status, thyroid function, and prostate cancer risk: follow-up of the First National Health and Nutrition Examination Survey

Few studies have investigated the association between iodine status, thyroid disease, and cancer risk despite evidence that thyroid function impacts many organs, including the prostate. We investigated iodine status and prostate cancer risk prospectively using data from the NHANES I Epidemiologic Follow-up Study. Participants were stratified into tertiles according to the urinary iodine/creatinine ratio, as a marker of iodine exposure. As iodine is an integral constituent of thyroid hormones, we also examined the relationship between thyroid disease and prostate cancer risk. Relative to the group with low urinary iodine, the age-adjusted hazard ratio was higher (although marginally insignificant) in the moderate group, hazard ratio 1.33 (95% confidence interval 1.00-1.78), and significantly lower in the high group, 0.71 (0.51-0.99). Thyroid disease was associated with an increased prostate cancer risk, 2.34 (1.24-4.43). Similarly, > 10 yr since thyroid disease diagnosis was associated with an elevated risk, 3.38 (1.66-6.87). After adjusting for other confounding factors, only a history of thyroid disease, 2.16 (1.13-4.14), and > 10 yr since diagnosis of thyroid disease, 3.17 (1.54-6.51) remained significant. Although the role of dietary iodine remains speculative, a role for thyroid disease and/or factors contributing to thyroid disease as a risk factor for prostate carcinogenesis warrants additional investigation.     

A multilevel analysis of socioeconomic status and prostate cancer risk

PURPOSE: We investigated whether prostate cancer was associated with socioeconomic status (SES) at the individual level, area level, or a combination of both levels. METHODS: This population-based case-control study of prostate cancer in men aged 65 to 79 years was conducted between 2000 and 2002 in South Carolina. Complete interviews were available for 407 incident prostate cancer cases and 393 controls (with respective response rates of 61% and 64%). We used educational level to measure individual-level SES and a composite variable capturing income and education from 2000 Census data to measure area-level SES. RESULTS: After adjustment for race, age, geographic region, and prostate-specific antigen testing, men with some college were at reduced risk for prostate cancer (odds ratio [OR], 0.44; 95% confidence interval [CI], 0.27-0.72), as were men in the highest quartile of area-level SES (OR, 0.52; 95% CI, 0.34-0.80). When assessing individual-level and area-level SES simultaneously and accounting for their nonindependence, the independent negative associations persisted and appeared to be more striking for men with a diagnosis of localized disease, rather than advanced disease. CONCLUSION: The independent effects of area-level and individual-level SES on prostate cancer risk seen in our study may help explain the conflicting results of previous studies conducted at both levels.     

A prospective cohort study of postmenopausal hormone use and risk of breast cancer in US women

The association between history of postmenopausal hormone use as of 1976 and breast cancer incidence during 1976-1980 was examined prospectively among 33,335 married, postmenopausal registered nurses aged 30-55 years at entry. Half the women reported postmenopausal hormone use, and one fourth had taken these drugs for over five years. During 1976-1980, 221 new cases of breast cancer were identified. The relative risk (RR) for those who had used postmenopausal hormones when compared with women who had never used them was 1.1 (95% confidence limits (CL) 0.8, 1.4); for current and past users, the relative risks were 1.0 (95% CL 0.7, 1.4) and 1.3 (95% CL 0.9, 1.8), respectively. These ratios were not substantially modified by whether or not a woman's ovaries had been removed or by other known breast cancer risk factors. No increase in breast cancer risk was apparent among women who had used postmenopausal hormones for less than five years (RR = 1.0, 95% CL 0.5, 1.6). An apparent effect among the subgroup of women who had used them for five to nine years (RR = 1.5, 95% CL 1.0, 2.2) was not present among the few women with longer-term use (RR = 0.9, 95% CL 0.4, 1.6). These findings are moderately reassuring, but since there are as yet few women in this cohort with long-term durations of use and, particularly, with long intervals since first use, continued follow-up of this and other cohorts will be required before firm conclusions can be drawn, especially among specific subgroups.     

Tea consumption and the risk of overall and grade specific prostate cancer: a large prospective cohort study of Scottish men

Tea may be a potentially modifiable and highly prevalent risk factor for the most common cancer in men, prostate cancer. However, associations between black tea consumption and prostate cancer in epidemiological studies have been inconsistent, limited to a small number of studies with small numbers of cases and short follow-up periods and without grade-specific information. We conducted a prospective cohort study of 6,016 men who were enrolled in the Collaborative Cohort Study between 1970 and 1973 and followed up to December 31, 2007. We used Cox proportional hazards models to investigate the association between tea consumption and overall as well as grade-specific risk of prostate cancer incidence. Three hundred and eighteen men developed prostate cancer in up to 37?years of follow-up. We found a positive association between consumption of tea and overall risk of prostate cancer incidence (P = 0.02). The association was greatest among men who drank ≥7 cups of tea per day (HR: 1.50, 95% CI: 1.06 to 2.12), compared with the baseline of 0-3 cups/day. However, we did not find any significant association between tea intake and low- (Gleason <7) or high-grade (Gleason 8-10) prostate cancer incidence. Men with higher intake of tea are at greater risk of developing prostate cancer, but there is no association with more aggressive disease. Further research is needed to determine the underlying biological mechanisms for the association.     

社会经济地位、健康生活方式与高血压发病的前瞻性队列研究

目的  探讨社会经济地位(socioeconomic status, SES)、健康生活方式与高血压发病的关系,为高血压的防控提供参考依据。方法  采用分层整群随机抽样于2010年对抽取的贵州省12个县(市、区)≥18岁常住居民共9 280人进行基线调查,于2016—2020年对该队列所有人群进行随访;采用t检验、χ²检验进行单因素分析,使用Cox比例风险回归模型分析SES、健康生活方式对高血压发病的影响。结果  研究有效样本量为3 401人,高血压发病765人,人群高血压发病密度为32.53/1 000人年。多因素Cox回归结果显示：与低SES(＜9分)人群相比,高SES(≥9分)人群高血压发病风险下降29.9%(HR=0.701, 95% CI: 0.584~0.842);与≤2种健康生活方式的人群相比,4种、≥5种健康生活方式人群发病风险分别降低25.7%(HR=0.743, 95% CI: 0.581~0.950)、39.2%(HR=0.608, 95% CI: 0.455~0.812)。与SES低且健康生活方式≤2种的人群相比,SES低且具有3种、4种、≥5种健康生活方式人群高血压发病风险的差异均无统计学意义(均有P＞0.05);SES高且具有3种、4种、≥5种健康生活方式的人群高血压发病风险分别降低36.3%(HR=0.637, 95% CI: 0.446~0.909)、44.0%(HR=0.560, 95% CI: 0.391~0.802)、55.8%(HR=0.442, 95% CI: 0.295~0.662)。结论  SES较低人群是贵州省高血压防控的重点人群,应采取措施提高其SES,并有针对性地开展健康教育与健康促进工作。     

高血压与男性性功能障碍发生风险的前瞻性队列研究

目的探讨高血压与男性性功能障碍发病风险的关系。方法采用前瞻性队列研究方法,随机抽取2015年中国人民解放军联勤保障部队第九二三医院进行健康体检的30~40岁已婚男性1000例进行基线调查,实际调查892人,有效应答率89.2%,剔除不符合调查条件者78例,最终可纳入研究对象为814例。按基线调查有或无高血压情况分为高血压组和正常血压组。随后开展3年随访,并剔除在随访中新发影响性功能的器质性疾病者、随访期服用降压药者、失访者,共135例。最后可纳入数据统计分析共679例。采用Cox模型分析高血压与男性性功能障碍发病风险比及95%可信区间(95%CI)。结果高血压组177例(26.07%),正常血压组502例(73.93%)。开展3年随访发现高血压组患者的性功能障碍发生率为48.58%,明显高于正常血压组的15.54%,差异有统计学意义(P<0.05)。Cox回归单因素结果显示,高血压组性功能障碍发病风险是正常血压组的2.056倍;调整高血压患者的年龄、BMI、饮酒、吸烟、职业类型、夫妻关系、高血脂症史和糖尿病史因素后,Cox回归多因素分析结果显示,高血压组性功能障碍发病风险是正常血压组的3.133倍。结论高血压是增加男性性功能障碍发生风险的危险因素,临床中应密切关注男性高血压患者的情况,并及早采取措施预防或避免性功能障碍发生。     

A prospective study of fruits, vegetables, and risk of endometrial cancer

Case-control studies support a lower risk of endometrial cancer associated with greater vegetable consumption but not fruit consumption. One prospective study suggested an inverse association with fruits and vegetables combined. The authors examined associations for vegetables and fruits separately among women in the American Cancer Society's Cancer Prevention Study II Nutrition Cohort. After exclusions, 41,400 postmenopausal women completed a questionnaire on diet, lifestyle, and medical history at baseline in 1992-1993. Information on diet was updated in 1999; historical dietary information from 1982 was also available. The authors identified 435 eligible cases of endometrial cancer through 2003. In multivariate models, neither fruit consumption (top quintile vs. bottom: rate ratio (RR) = 1.24, 95% confidence interval (CI): 0.90, 1.70; p-trend = 0.30) nor vegetable consumption (RR = 1.21, 95% CI: 0.89, 1.65; p-trend = 0.24) at baseline was associated with risk. Results were similar when diet was cumulatively updated. Only among women who had never used hormone replacement therapy was the risk of endometrial cancer lower in the highest (vs. lowest) tertile of fruit (RR = 0.75, 95% CI: 0.52, 1.07; p-interaction = 0.03, p-trend = 0.11) or vegetable (RR = 0.80, 95% CI: 0.57, 1.13; p-interaction = 0.01, p-trend = 0.29) consumption. This prospective study does not support an association between vegetable or fruit consumption and endometrial cancer.     

基线BMI水平对急性胰腺炎发病风险影响的前瞻性队列研究

目的 探讨不同BMI水平对新发急性胰腺炎（AP）发病风险的影响。方法 观察人群来自开滦研究队列,按基线BMI水平分为：正常体重组（BMI<24 kg/m²）,超重组（BMI 24~28 kg/m²）和肥胖组（BMI ≥ 28 kg/m²）,观察不同BMI组人群新发AP发病密度。经Kaplan-Meier法绘制生存曲线,计算累积发病率,以log-rank法进行检验,并采用多因素Cox比例风险回归模型分析基线BMI水平对新发AP事件的影响。结果 共纳入统计分析者123 841人,随访（11.94±2.13）年,共发生AP 395例,总人群AP发病密度为2.67例/万人年,正常体重组、超重组和肥胖组AP发病密度分别为2.20、2.72和3.58例/万人年,累积发病率分别为0.32%、0.40%和0.49%。经log-rank检验,累积发病率的组间比较差异有统计学意义（χ²=13.17,P<0.01）。校正多因素Cox比例风险回归模型分析显示,与正常体重组比较,肥胖组AP发病风险增加,HR=1.45（95%CI：1.10~1.92）。对年龄及性别进行分层,年龄<60岁时,肥胖组发生AP的HR=1.58（95%CI：1.14~2.19）;男性肥胖组发生AP的HR=1.40（95%CI：1.03~1.90）。排除随访2年内发生的AP病例,肥胖组发生AP的HR=1.60（95%CI：1.18~2.15）。结论 肥胖是新发AP的危险因素,中青年男性肥胖人群发病风险更高。     

Oral contraceptives, reproductive factors, and risk of colorectal cancer among women in a prospective cohort study

Previous findings on the associations between oral contraceptive (OC) use and reproductive factors and risk of colorectal cancer have been inconclusive. The authors evaluated associations of OC use and reproductive factors (including parity, age at first birth, age at menarche, and age at menopause) with risk of colorectal cancer among women in a large-scale prospective cohort study. The analysis included 39,680 participants in the Women's Health Study who had usable information on ever use of OCs and potential risk factors for colorectal cancer. Relative risks and 95% confidence intervals were estimated from Cox proportional hazards regression models. All p values were two-sided. During an average of 11 years of follow-up (1992-2004), 267 incident cases of colorectal cancer were documented. Ever use of OCs was associated with a lower risk of colorectal cancer (relative risk = 0.67, 95% confidence interval: 0.50, 0.89). Women who had used OCs for 6 months-<3 years had a relative risk of 0.61 (95% confidence interval: 0.40, 0.94) relative to never users, with little additional decreased risk being seen with longer duration of use (p for multivariate trend = 0.09). No significant association was observed between reproductive factors and colorectal cancer risk. These findings provide some support for a potential role of OCs in reducing risk of colorectal cancer.