Cigarette smoking as a predictor of death from prostate cancer in 348,874 men screened for the Multiple Risk Factor Intervention Trial

Risk of urinary tract cancers following arsenic exposure and tobacco smoking: a review

Bladder cancer, prostate cancer, and kidney cancer, due to their high morbidity and mortality rates, result in significant economic and health care costs. Arsenic exposure affects the drinking water of millions of people worldwide. Long-term exposure to arsenic, even in low concentrations, increases the risk of developing various cancers. Smoking is also one of the leading causes of bladder, prostate and kidney cancers. Accordingly, this research reviews the relationship between arsenic exposure and smoking with three kinds of urinary tract cancers (bladder cancer, prostate cancer, and kidney cancer) due to their widespread concern for their negative impact on public health globally. In this review, we have gathered the most current information from scientific databases [PubMed, Scopus, Google Scholar, ISI web of science] regarding the relationship between arsenic exposure and tobacco smoking with the risk of bladder, prostate, and kidney cancer. In several studies, a significant relationship was determined between the incidence and mortality rate of the above-mentioned cancers in humans with arsenic exposure and tobacco smoking. The decrease or cessation of smoking and consumption of arsenic-free water significantly declined the incidence of bladder, prostate, and kidney cancers.

Diabetes mellitus and the risk of prostate cancer: an update and cumulative meta-analysis

INTRODUCTION

To provide further insight into the association between type 2 diabetes mellitus (T2DM) and the pathophysiology of prostate cancer, we conducted an updated, detailed meta-analysis of 56 published case-control and cohort studies.

METHODS

MEDLINE and EMBASE were used to identify the literature published in April 2012 related to both diabetes mellitus and prostate cancer. A sensitivity analysis was performed, and potential confounding effects were investigated using a stratified meta-analysis. A cumulative meta-analysis was also carried out to evaluate the cumulative effect estimate over time.

RESULTS

A total of 24 case-control and 32 cohort studies with information on a total of ~8,000,000 subjects and ~140,000 individuals with prostatic cancer showed published estimates of the association between diabetes and prostate cancer malignancy. The pooled effect estimate revealed a relative risk (RR) of 0.88 (95% CI, 0.82-0.93). Interestingly, there was an increased trend for Asians (RR = 1.72, n = 7) but not Americans (RR = 0.82, n = 28) and Europeans (RR = 0.86, n = 21) regarding the association between diabetes mellitus and prostate cancer. The sensitivity analysis, excluding any one study, did not significantly change the pooled RR. The range for the pooled RR when one study was omitted was 0.84-0.89.

DISCUSSION

The findings of our meta-analysis provide strong evidence of an inverse association between diabetes and prostate cancer.

CONCLUSIONS

Further research should focus on limitations in the current literature and re-assess the relationship between diabetes and prostate cancer by analyzing the two different diabetes mellitus types separately.

A systematic review and meta-analysis of tobacco use and prostate cancer mortality and incidence in prospective cohort studies

CONTEXT

An association between tobacco smoking and prostate cancer (PCa) incidence and mortality was suggested in an earlier meta-analysis of 24 prospective studies in which dose-response associations and risks per unit of tobacco use were not examined.

OBJECTIVE

We investigated the association between several measures of tobacco use and PCa mortality (primary outcome) and incidence (secondary outcome) including dose-response association.

EVIDENCE ACQUISITION

Relevant articles from prospective studies were identified by searching the PubMed and Web of Science databases (through January 21, 2014) and reference lists of relevant articles. Combined relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random effects methods. We also calculated population attributable risk (PAR) for smoking and PCa mortality.

EVIDENCE SYNTHESIS

We included 51 articles in this meta-analysis (11823 PCa deaths, 50349 incident cases, and 4,082,606 cohort participants). Current cigarette smoking was associated with an increased risk of PCa death (RR: 1.24; 95% CI, 1.18-1.31), with little evidence for heterogeneity and publication bias. The number of cigarettes smoked per day had a dose-response association with PCa mortality (p=0.02; RR for 20 cigarettes per day: 1.20). The PAR for cigarette smoking and PCa deaths in the United States and Europe were 6.7% and 9.5%, respectively, corresponding to >10000 deaths/year in these two regions. Current cigarette smoking was inversely associated with incident PCa (RR: 0.90; 95% CI, 0.85-0.96), with high heterogeneity in the results. However, in studies completed in 1995 or earlier (considered as completed before the prostate-specific antigen screening era), ever smoking showed a positive association with incident PCa (RR: 1.06; 95% CI, 1.00-1.12) with little heterogeneity.

CONCLUSIONS

Combined evidence from observational studies shows a modest but statistically significant association between cigarette smoking and fatal PCa. Smoking appears to be a modifiable risk factor for PCa death.

PATIENT SUMMARY

Smoking increases the chance of prostate cancer death. Not smoking prevents this harm and many other tobacco-related diseases.

Smoking and risk of low- and high-grade prostate cancer: results from the REDUCE study

PURPOSE

Although the relationship between smoking and prostate cancer risk is inconsistent, some studies show that smoking is associated with prostate cancer mortality. Whether this reflects delayed diagnosis or direct smoking-related effects is unknown. REDUCE, which followed biopsy-negative men with protocol-dictated prostate-specific antigen (PSA)-independent biopsies at 2 and 4 years, provides an opportunity to evaluate smoking and prostate cancer diagnosis with minimal confounding from screening biases.

EXPERIMENTAL DESIGN

Logistic regression was conducted to test the association between smoking and cancer on the first on-study biopsy (no cancer, low-grade Gleason 4-6, high-grade Gleason 7-10) in REDUCE.

RESULTS

Of 6,240 men with complete data and ≥1 on-study biopsy, 2,937 (45.8%) never smoked, 929 (14.5%) were current smokers, and 2,554 (39.8%) were former smokers. Among men with negative first on-study biopsies, smokers were 36% less likely to receive a second on-study biopsy (P < 0.001). At first on-study biopsy, 941 (14.7%) men had cancer. Both current and former smoking were not significantly associated with either total or low-grade prostate cancer (all P > 0.36). Current (OR = 1.44, P = 0.028) but not former smokers (OR = 1.21, P = 0.12) were at increased risk of high-grade disease. On secondary analysis, there was an interaction between smoking and body mass index (BMI; Pinteraction = 0.017): current smokers with BMI ≤ 25 kg/m(2) had an increased risk of low-grade (OR = 1.54, P = 0.043) and high-grade disease (OR = 2.45, P = 0.002), with null associations for BMI ≥ 25 kg/m(2).

CONCLUSION

Among men with elevated PSA and negative pre-study biopsy in REDUCE, in which biopsies were largely PSA independent, smoking was unrelated to overall prostate cancer diagnosis but was associated with increased risk of high-grade prostate cancer.

Diabetes mellitus and prostate cancer risk of different grade or stage: a systematic review and meta-analysis

AIM

Prior studies have reported that diabetes mellitus might reduce the overall prostate cancer risk. We examined this association by conducting a detailed meta-analysis of the studies published in peer-reviewed literature on the association between diabetes mellitus and prostate cancer risk of different stage or grade.

METHODS

A comprehensive search for articles of MEDLINE and EMBASE databases and bibliographies of retrieved articles published up to October 23, 2012 was performed. Methodological quality assessment of the trials was based on the Newcastle-Ottawa Scale. Meta-analysis was performed using STATA 12.0.

RESULTS

We included 9 studies in the meta-analysis (5 studies examining the relation of different stage only, 2 studies for grade only, and 2 studies for both grade and stage), and found an inverse association between diabetes mellitus and prostate cancer of different stage or grade. The relative risk (RRs) was moderately stronger for low grade (RR 0.74, 95% confidence interval (CI), 0.64-0.86) and localized disease (RR 0.72, 95% CI 0.67-0.76) compared with high grade (RR 0.78, 95% CI 0.67-0.90) and advanced disease (RR 0.85, 95% CI 0.75-0.97).

CONCLUSION

This study suggests an inverse relationship between diabetes mellitus and prostate cancer of different stage or grade. Possible biases underlying this association are discussed.

Diabetes mellitus and risk of prostate cancer: an updated meta-analysis based on 12 case-control and 25 cohort studies

The association between diabetes and risk of prostate cancer has been investigated widely. However, study results remain inconsistent and contradictory. Using a meta-analytic approach, the present study explore the relationship incorporating more recent studies and provide more powerful evidence without the limitations of any individual study. Relevant studies were identified by searching Pubmed and the Cochrane Central Register of Controlled Trials through May 18, 2012. The strength of the relationship between diabetes mellitus and risk of prostate cancer was assessed using relative risk (RR). Either a fixed effects or random effects model was used to calculate the pooled RRs. Stratification analyses and sensitivity analyses were conducted, and publication bias was assessed by Egger's test and Begg's test. Twelve case-control studies involving 9,767 cases and 19,790 controls, and 25 cohort studies involving 118,825 cases were included. The person-years of follow-up ranged from 29,963 to 6,264,890 among included cohort studies. Diabetes was not significantly associated with incidence of prostate cancer in our analysis of case-control studies only (RR = 0.846, 95 % CI [0.710, 1.009]) or that of cohort studies only (RR = 0.925, 95 % CI [0.811, 1.054]). However, through subgroup analyses, statistically significant associations between diabetes and prostate cancer were found when considering population-based studies only (RR = 0.719, 95 % CI [0.637, 0.812]), cohort studies conducted in the United States (RR = 0.789, 95 % CI [0.727, 0.857]), and studies with follow-up of more than 5 years. Compared to risk of prostate cancer among people without diabetes, diabetic patients using insulin treatment experienced reduced incidence of prostate cancer in both case-control and cohort studies. The results suggest that diabetes mellitus is associated with decreased incidence of prostate cancer, specifically in the population of the United States. In addition, the time since onset of diabetes was positively associated with decreasing incidence of prostate cancer. The present conclusions should be considered carefully, however, and confirmed with further studies.

Smoking and the risk of prostate cancer in the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

Smoking is not associated with prostate cancer incidence in most studies, but associations between smoking and fatal prostate cancer have been reported.

METHODS

During 1992 and 2000, lifestyle information was assessed via questionnaires and personal interview in a cohort of 145,112 European men. Until 2009, 4623 incident cases of prostate cancer were identified, including 1517 cases of low-grade, 396 cases of high grade, 1516 cases of localised, 808 cases of advanced disease, and 432 fatal cases. Multivariable Cox proportional hazards regression models were used to examine the association of smoking status, smoking intensity, and smoking duration with the risk of incident and fatal prostate cancer.

RESULTS

Compared with never smokers, current smokers had a reduced risk of prostate cancer (RR=0.90, 95% CI: 0.83-0.97), which was statistically significant for localised and low-grade disease, but not for advanced or high-grade disease. In contrast, heavy smokers (25+ cigarettes per day) and men who had smoked for a long time (40+ years) had a higher risk of prostate cancer death (RR=1.81, 95% CI: 1.11-2.93; RR=1.38, 95% CI: 1.01-1.87, respectively).

CONCLUSION

The observation of an increased prostate cancer mortality among heavy smokers confirms the results of previous prospective studies.

Smoking at diagnosis and survival in cancer patients

The effect of smoking on survival in cancer patients is limited by the lack of structured prospective assessments of smoking at diagnosis. To assess the effect of smoking at diagnosis on survival, structured smoking assessments were obtained in a cohort of 5,185 cancer patients within 30 days of a cancer diagnosis between 1982 and 1998. Hazard ratios (HRs) or odds ratios were generated to analyze the effects of smoking at diagnosis on overall mortality (OM) and disease-specific mortality (DSM) in a patient cohort from 13 disease sites containing at least 100 patients in each disease site. With a minimum of 12 years of follow-up, current smoking increased OM risk versus recent quit (HR 1.17), former (HR 1.29) and never smokers (HR 1.38) in the overall cohort. Current smoking increased DSM risk versus former (HR 1.23) and never smokers (HR 1.18). In disease sites with proportionately large (>20%) recent quit cohorts (lung and head/neck), current smoking increased OM and DSM risks as compared with recent quit. Current smoking increased mortality risks in lung, head/neck, prostate and leukemia in men and breast, ovary, uterus and melanoma in women. Current smoking was not associated with any survival benefit in any disease site. Data using prospective structured smoking assessments demonstrate that current smoking increased long-term OM and DSM. Standardized smoking assessment at diagnosis is an important variable for evaluating outcomes in cancer patients.

Cigarette smoking and risk of prostate cancer among Singapore Chinese

Prospective epidemiologic studies conducted in Western populations support an association between current smoking and aggressive subtypes of prostate cancer. In Singapore, where prostate-specific antigen is not used for population-wide screening, prostate cancer incidence has tripled within the past two decades. Using Cox regression methods, we examined the relationship between smoking and prostate cancer established between 1993 and 1998 in a cohort of 27,293 Singapore Chinese men. As of December 2006, 250 incident prostate cancer cases were diagnosed. In our cohort, 42.2% reported never smoking cigarettes, 15.7% quit over 5 years ago (long-term former), 5.7% quit within the past 5 years (recent former), and 36.4% were current smokers. From multivariable models, we observed no association with smoking status, age at starting to smoke, years smoked, or number of cigarettes per day. Among recent former and current smokers combined, we observed a small positive association for earlier age at starting to smoke that was somewhat stronger for nonadvanced disease (hazard ratio = 1.63, 95% confidence interval: 0.85, 3.12, for <15 years versus nonsmokers). Smoking was not a major risk factor for prostate cancer in our Singapore Chinese cohort, a traditionally low risk population with parallel increases in incidence and mortality.

Smoking and aggressive prostate cancer: a review of the epidemiologic evidence

Although tobacco use has been recognized as one of the leading causes of cancer morbidity and mortality, a role of smoking in the occurrence of prostate cancer has not been established. However, evidence indicates that factors that influence the incidence of prostate cancer may differ from those that influence progression and fatality from the disease. Thus, we reviewed and summarized results from prospective cohort studies that assessed the relation between smoking and fatal prostate cancer risk, as well as epidemiological and clinical studies that focused on aggressive behavior in prostate cancer, such as poorer survival, advanced stage, or poorer differentiation at diagnosis. The majority of the prospective cohort studies showed that current smoking is associated with a moderate increase of ~30% in fatal prostate cancer risk compared to never/non-smokers. This association is likely to be an underestimate of the effect of smoking because most studies had a single assessment of smoking at baseline and long follow-up times, and the association was considerably stronger in some sub-groups of heaviest smokers, or when smoking was assessed in a relatively short period (within 10 years) prior to cancer mortality. Using aggressive behavior of prostate cancer as outcome, current smoking was associated with significantly elevated risk, ranging from around twofold to threefold or higher. Although alternative explanations, such as publication bias, residual confounding, screening bias, and the influence of smoking-related comorbidities cannot be ruled out entirely, these findings suggest that smoking is associated with aggressive behavior of prostate cancers or with a sub-group of rapidly progressing prostate cancer. Based on evidence presented in this review, cigarette smoking is likely to be a risk factor for prostate cancer progression and should be considered as a relevant exposure in prostate cancer research and prevention of mortality from this cancer.

The association of diabetes mellitus and high-grade prostate cancer in a multiethnic biopsy series

OBJECTIVE

To analyze the association of diabetes mellitus (DM) with risk of prostate cancer and cancer grade among men undergoing prostate biopsy and to analyze how obesity and race modify these associations.

MATERIALS AND METHODS

Retrospective analysis of 998 men from the Durham VA undergoing first prostate biopsy between 2001 and 2009 with complete data available. History of DM was determined by chart review. Patients' characteristics at biopsy were analyzed with chi-square and ranksum. Multivariable analyses of DM and risk of cancer and cancer grade were done using logistic regression adjusting for PSA, body mass index, race, age, year, and digital rectal exam.

RESULTS

At biopsy, 284 (28%) men had DM. DM was associated with African American (AAM; p = 0.010) and higher BMI (p < 0.001). DM was not associated with prostate cancer risk on either bivariate (p = 0.600) or multivariate analysis (p = 0.485). Similar results were found after stratification by race and obesity. In multivariable analysis, DM was associated with greater risk of high-grade disease (RR = 2.13, p = 0.024). The association was stronger among obese men (RR = 3.84, p = 0.020) and null in non-obese subjects (RR = 1.39, p = 0.460). After further stratification by race, DM was associated with high-grade disease only in obese Caucasian men (CM; RR = 5.81, p = 0.025) but not in obese AAM. DM was not associated with risk of low-grade disease in all men together or after stratification by obesity or race.

CONCLUSION

History of DM was associated with greater risk of high-grade disease. The association was strongest among obese CM suggesting the effect of DM on high-grade prostate cancer is modified by race and obesity.

Overexpression of aldo-keto reductase 1C2 is associated with disease progression in patients with prostatic cancer

AIMS

Prostatic cancer is resistant to chemotherapy. Expression of aldo-keto reductase 1C (AKR1C) has been associated with drug resistance and disease progression in several cancers. The aim was to investigate the relationship between AKR1C expression and disease progression in prostatic cancer.

METHODS AND RESULTS

From January 1996 to December 2005, 86 pathological samples were collected from patients with prostatic cancer. A tissue microarray containing 31 prostatic cancers from American patients was used for comparison between Chinese and American patients. Using immunohistochemistry, aldo-keto reductase family 1, member C2 (AKR1C2) expression was assessed in tissue sections. The AKR1C2 was determined by two-dimensional immunoblotting and DNA sequencing of reverse transcriptase-polymerase chain reaction products. The relationship between AKR1C2 expression and clinicopathological variables was statistically analysed. In vitro, the association between AKR1C2 expression and drug resistance was investigated in androgen-sensitive and androgen-insensitive prostatic cancer cells. DNA sequencing and two-dimensional immunoblotting showed that prostatic cancer expressed AKR1C2. It was overexpressed in 77 of 86 (89.5%) Chinese and in 28 of 31 (90.3%) American samples. No difference was found in AKR1C2 expression between Chinese and American prostatic cancer patients. In vitro, increased expression of AKR1C2 and prostaglandin F2α correlated with cytoprotection against anticancer drugs and lycopene.

CONCLUSION

Overexpression of AKR1C2 is associated with disease progression in prostatic cancer.

Selenium and cadmium levels and ratios in prostates, livers, and kidneys of nonsmokers and smokers

Cadmium (Cd) from cigarette smoke, environmental, and nutritional sources accumulates in the human prostate where it interacts with selenium (Se) in a manner suggesting the formation of a 1:1 Cd-Se-protein complex. At low Cd exposures and adequate Se status, this interaction may be beneficial as it results in the detoxification of Cd. At higher exposures, Cd may weaken or abolish the anticarcinogenic effects of Se and increase prostate cancer risk. In some older men and especially in smokers, Cd levels in prostates reach levels in stoichiometric excess over Se, which may be the reason why heavy smokers are at higher risk of developing lethal forms of prostate cancer. In the liver and the kidneys, Cd accumulates as well, but in these organs, Cd is efficiently sequestered through metallothionein formation. In the prostate, this mode of detoxification is not available or less efficient, causing Cd to interact with Se and to increase prostate cancer risk.

Medical history, body size, and cigarette smoking in relation to fatal prostate cancer

OBJECTIVES

Prostate cancer has few known risk factors. As part of a population-based case-control study conducted in four health maintenance organizations, the authors examined the associations between fatal prostate cancer and several medical and behavioral characteristics.

METHODS

Cases were 768 health plan members who died of prostate adenocarcinoma during the period 1997-2001. We randomly selected controls (929) from the health plan membership and matched them to cases on health plan, age, race, and pattern of health plan membership. We examined medical records to obtain information on potential risk factors during the 10 years before the date on which prostate cancer was first suspected; the same reference date was used for the matched controls.

RESULTS

Anthropometric characteristics, as well as personal histories of benign prostatic hypertrophy, transurethral prostatectomy, cancer, diabetes, prostatitis, hypertension, and vasectomy were largely similar for cases and controls. Men who died from prostate cancer were more likely than controls to have been cigarette smokers according to the most recent smoking notation before the reference date (odds ratio 1.5, 95% confidence interval 1.1-2.0).

CONCLUSIONS

The observed increase in risk associated with recent cigarette smoking is consistent with the findings of several other studies. However, in contrast with some reports, we observed no connection between fatal prostate cancer and some prior health conditions or measures of body size.

Smoking as a risk factor for prostate cancer: a meta-analysis of 24 prospective cohort studies

OBJECTIVES

We evaluated the relationship between smoking and adenocarcinoma of the prostate.

METHODS

We pooled data from 24 cohort studies enrolling 21 579 prostate cancer case participants for a general variance-based meta-analysis. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated separately for mortality and incidence studies. We tested the robustness of effect measures and evaluated statistical heterogeneity with sensitivity analyses.

RESULTS

In the pooled data, current smokers had no increased risk of incident prostate cancer (RR = 1.04; 95% CI = 0.87, 1.24), but in data stratified by amount smoked they had statistically significant elevated risk (cigarettes per day or years: RR = 1.22; 95% CI = 1.01, 1.46; pack years of smoking: RR = 1.11; 95% CI = 1.01, 1.22). Former smokers had an increased risk (RR = 1.09; 95% CI = 1.02, 1.16). Current smokers had an increased risk of fatal prostate cancer (RR = 1.14; 95% CI = 1.06, 1.19). The heaviest smokers had a 24% to 30% greater risk of death from prostate cancer than did nonsmokers.

CONCLUSIONS

Observational cohort studies show an association of smoking with prostate cancer incidence and mortality. Ill-defined exposure categories in many cohort studies suggest that pooled data underestimate risk.

Dynamic effects of smoking cessation on disease incidence, mortality and quality of life: The role of time since cessation

Background

To support health policy makers in setting priorities, quantifying the potential effects of tobacco control on the burden of disease is useful. However, smoking is related to a variety of diseases and the dynamic effects of smoking cessation on the incidence of these diseases differ. Furthermore, many people who quit smoking relapse, most of them within a relatively short period.

Methods

In this paper, a method is presented for calculating the effects of smoking cessation interventions on disease incidence that allows to deal with relapse and the effect of time since quitting. A simulation model is described that links smoking to the incidence of 14 smoking related diseases. To demonstrate the model, health effects are estimated of two interventions in which part of current smokers in the Netherlands quits smoking.

To illustrate the advantages of the model its results are compared with those of two simpler versions of the model. In one version we assumed no relapse after quitting and equal incidence rates for all former smokers. In the second version, incidence rates depend on time since cessation, but we assumed still no relapse after quitting.

Results

Not taking into account time since smoking cessation on disease incidence rates results in biased estimates of the effects of interventions. The immediate public health effects are overestimated, since the health risk of quitters immediately drops to the mean level of all former smokers. However, the long-term public health effects are underestimated since after longer periods of time the effects of past smoking disappear and so surviving quitters start to resemble never smokers. On balance, total health gains of smoking cessation are underestimated if one does not account for the effect of time since cessation on disease incidence rates. Not taking into account relapse of quitters overestimates health gains substantially.

Conclusion

The results show that simulation models are sensitive to assumptions made in specifying the model. The model should be specified carefully in accordance with the questions it is supposed to answer. If the aim of the model is to estimate effects of smoking cessation interventions on mortality and morbidity, one should include relapse of quitters and dependency on time since cessation of incidence rates of smoking-related chronic diseases. A drawback of such models is that data requirements are extensive.

Cigarette smoking and prostate cancer-specific mortality following diagnosis in middle-aged men

OBJECTIVE

The aim of this study was to examine associations of smoking at the time of diagnosis with the risk of prostate cancer death in a population-based cohort of men with prostate cancer.

METHODS

Data were from 752 prostate cancer patients aged 40-64 years, who were enrolled in a case-control study and under long-term follow-up for mortality. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations between smoking and prostate cancer-specific and other cause mortality.

RESULTS

Compared to never smoking, smoking at the time of diagnosis was associated with a significant increase in risk of prostate cancer-specific mortality. After controlling for demographic characteristics, Gleason grade, stage at diagnosis, and primary treatment, the HR was 2.66 (95% CI: 1.10-6.43).

CONCLUSIONS

Smoking at the time of diagnosis, independent of key clinical prognostic factors, is associated with an increased risk of prostate cancer death.

The association between paternal prostate cancer and type 2 diabetes

Objective

Increasing evidence indicates that type 2 diabetic patients are at elevated risk for developing different kinds of cancers. However, diabetes mellitus may be a protective factor for prostate cancer since both were found to be negatively associated. Based on the same genetic background, parents of diabetic patients might show similar risks concerning cancers.

Research design and methods

We conducted a case-control study, where familiy history of 794 type 2 diabetic cases and 775 non-diabetic controls was ascertained. Then, we expanded our study up to 801 type 2 diabetic cases and 1267 non-diabetic controls.

Results

Concerning the 794 type 2 diabetic patients and 775 controls, we observed that cancer of cervix uteri was elevated among mothers of controls (odds ratio (OR) 0.19; 95% confidence interval (CI) 0.02 to 0.88; p = 0.033). Mothers of diabetic patients showed an increased history of cancers of the liver and biliary tract (OR 5.23; 95% CI 1.87 to 19.9; p = 0.0009) and stomach (OR 3.84; 95% CI 1.47 to 12.4; p = 0.0049). Pancreatic cancers were found to be elevated in fathers of diabetic patients (OR 4.92; 95% CI 1.07 to 46.7; p = 0.039). Most notably, a lower number of prostate cancers was observed in fathers of diabetic patients (OR 0.47; 95% CI 0.22 to 0.94; p = 0.032). Since diabetic patients were 14.3 years older than the controls, higher levels of cancer history among parents of diabetic patients would have been expected. Thus, the observed lower level of history of prostate cancer can be regarded as highly reliable.

The analysis of 801 type 2 diabetics and 1267 controls showed that cancer of stomach was elevated among mothers of controls (OR 2.67; p = 0.0106). In addition, stomach cancers were found to be elevated in fathers of diabetic patients (OR 2.10; p = 0.0141). In accordance with the previous investigation, we again obseved a lower number of prostate cancers in fathers of diabetic patients (OR 0.49; p = 0.0279).

However, the application of the statistical method of Mantel-Haenszel showed no significant result concerning any of the cancer histories.

Conclusion

Fathers of patients suffering from type 2 diabetes were diagnosed less frequently with prostate cancer compared to fathers of non-diabetic controls. As first-degree relatives, e.g. diabetic patients and their fathers, share 50% of their genes, it appears plausible that genetic factors may play an important role in the negative association between diabetes and prostate cancer. However, different statistic analyses showed controversial results concerning the effect of type 2 diabetes on prostate cancers.

[Does cigarette smoking influence the survival of patients with prostate cancer?]

In the last few years, prostate cancer has become one of the most common causes of mortality worldwide. It is therefore important to detect possible risk factors for this malignant disease. Besides risk factors which increase incidence, attention should be paid to factors which have a possible influence on the course of the disease. In our analysis, we demonstrate a worse course for the disease in patients with prostate cancer who smoked cigarettes at the time of first diagnosis. In spite of comparable staging, grading and PSA values at the time of primary diagnosis, individuals who smoked had a threefold higher risk of dying from prostate cancer. This effect is probably caused by metabolic changes which are activated by cigarette smoking and promote tumor growth and the development of metastases.

A meta-analysis of diabetes mellitus and the risk of prostate cancer

BACKGROUND

Studies investigating the association between diabetes mellitus and prostate cancer have reported inconsistent findings. We examined this association by conducting a detailed meta-analysis of the studies published on the subject.

METHODS

MEDLINE and EMBASE databases and bibliographies of retrieved articles were searched. Studies investigating the relationship between diabetes mellitus and prostate cancer were included in the meta-analysis. Potential sources of heterogeneity between studies were explored and publication bias was evaluated. Pooled relative risk (RR) was calculated using the random-effects model. Numerous relevant subgroup analyses were also done.

RESULTS

We included 19 studies, published between 1971 and 2005, in the meta-analysis and found an inverse association between diabetes mellitus and prostate cancer [RR, 0.84, 95% confidence interval (CI), 0.76-0.93, P for heterogeneity <or= 0.01]. For cohort studies alone, the RR was 0.81 (95% CI, 0.71-0.92, P for heterogeneity <or= 0.01) and for case-control studies alone, the RR was 0.89 (95% CI, 0.72-1.11, P for heterogeneity = 0.02). The significant heterogeneity was mitigated in some of the subgroup analyses. For studies conducted before prostate-specific antigen screening was introduced as a common procedure, the RR was 0.94 (95% CI, 0.85-1.03, P for heterogeneity = 0.15), and for studies conducted after this time, the RR was 0.73 (95% CI, 0.64-0.83, P for heterogeneity = 0.10). For studies that adjusted for three or more potential confounders, the RR was 0.74 (95% CI, 0.65-0.85, P for heterogeneity = 0.06) and for studies that adjusted for less than three potential confounders, the RR was 0.93 (95% CI, 0.86-1.02, P for heterogeneity = 0.18).

CONCLUSION

This study suggests an inverse relationship between diabetes and prostate cancer. Potential biological mechanisms underlying this association, as well as possible biases, are discussed.

Smoking and risk of fatal prostate cancer in a prospective U.S. study

OBJECTIVES

To examine the association of cigarette smoking with subsequent fatal prostate cancer.

METHODS

Two private censuses were conducted in Washington County, Maryland, in which 26,810 adult men in 1963 and 28,292 in 1975 provided smoking information. Prostate cancer deaths through 2000 (1963 cohort, 240 deaths; and 1975 cohort, 184 deaths) were ascertained by review of the death certificates. Poisson regression analysis was used to estimate the rate ratio of prostate cancer death adjusted for age.

RESULTS

Overall, cigarette smokers in the 1963 census cohort were not more likely to die of prostate cancer than those who had never smoked cigarettes, pipes, or cigars when considering the total follow-up period. However, current smokers of 20 or more cigarettes per day (rate ratio 2.38; 95% confidence interval 0.94 to 5.99) and former smokers (rate ratio 2.75; 95% confidence interval 1.13 to 6.74) had a greater risk of death from prostate cancer during the first 10 years of follow-up. Weaker positive associations of prostate cancer death with current and former cigarette smoking were seen during the first 10 years of follow-up in the 1975 census cohort. Current cigarette smoking at baseline was not associated with the prostate cancer incidence.

CONCLUSIONS

The lack of an association between cigarette smoking and prostate cancer incidence, but the tendency of greater prostate cancer mortality in former and current cigarette smokers earlier in the follow-up period is consistent with other studies in which smoking was assessed once at baseline.

History of diabetes mellitus and subsequent prostate cancer risk in the NIH-AARP Diet and Health Study

OBJECTIVE

A history of diabetes has been hypothesized to decrease prostate cancer risk, but studies have not always considered confounding or effect modification by dietary or lifestyle factors.

METHODS

We examined the association between diabetes history and subsequent prostate cancer risk in 328,316 men enrolled in the NIH-AARP Diet and Health Study. Participants were ages 50-71 years and without a prostate cancer diagnosis at baseline in 1995. A prior history of physician-diagnosed diabetes was assessed using a self-administered mailed questionnaire. Cases of prostate cancer were ascertained by matching the cohort to state cancer registries. Multivariable relative risks (RR) and 95% confidence intervals (CI) of prostate cancer were estimated using Cox regression.

RESULTS

During 5 years and 1,432,676 person-years of follow-up, 11,193 prostate cancer cases were ascertained. The age-adjusted and multivariable RRs of prostate cancer comparing men with diabetes to those without diabetes were 0.69 (95% CI=0.64, 0.74) and 0.71 (95% CI=0.66, 0.76), respectively, indicating no important confounding. The inverse association between diabetes and prostate cancer was particularly strong among men in the highest category of routine physical activity at work or home (RR=0.41; 95% CI=0.23, 0.74; p value for test of interaction = 0.03). Findings were similar for organ-confined and advanced prostate cancer.

CONCLUSION

Results from this large prospective study suggest that a history of diabetes is associated with a decreased risk of prostate cancer. The relationship strengthened with high levels of routine physical activity. Because increased physical activity is associated with lower circulating levels of insulin and testosterone, our findings support a role of hypoinsulinemia and low androgenicity linking diabetes to decreased prostate cancer risk.

Diabetes Mellitus and the Risk of Prostate Cancer in Italy

OBJECTIVE

We investigated the relation between diabetes and the risk of prostate cancer, as epidemiological results are controversial.

METHODS

A hospital-based case-control study was conducted in Italy between 1991 and 2002. Cases were 1294 men, aged <75 years, with incident histologically confirmed prostate cancer, and controls were 1451 men, aged <75 years, admitted to hospital for acute non-neoplastic diseases. Odds ratios (OR) and the corresponding 95% confidence intervals (CI) were estimated using unconditional multiple logistic regression models.

RESULTS

No material association between diabetes and prostate cancer was observed, with a multivariate OR of 1.02 (95%CI 0.75-1.40). Prostate cancer was not related to time since diagnosis of diabetes (OR 0.82 and 0.97 for <5 and >/=15 years since diagnosis respectively). The OR were respectively 1.63 (95%CI 0.70-3.81) and 0.96 (95%CI 0.68-1.34) in men diagnosed with diabetes at age <45 or >/=45 years. The risk estimates were similar across strata of age at interview, body mass index and, among cases, of Gleason score.

CONCLUSIONS

This study shows no material association between diabetes and prostate cancer risk.

Diabetes mellitus and prostate cancer risk among older men: population-based case-control study

We investigate the relation between diabetes mellitus and risk of prostate cancer among older (age 65–79 years) men in a population-based case–control study of 407 incident histologically confirmed cases registered in the South Carolina Central Cancer Registry between 1999 and 2001 (70.6% response rate); controls were 393 men identified through the Health Care Financing Administration Medicare beneficiary file for South Carolina in 1999 (63.8% response rate). After adjusting for age, race, and prostate cancer screening in the past 5 years, a history of diabetes mellitus was associated with a reduced risk of prostate cancer (adjusted odds ratio (aOR)=0.64; 95% confidence interval (CI)=0.45, 0.91). The protective effect was stronger for those with complications associated with diabetes (aOR=0.61; 95% CI=0.42, 0.90) and for African-American men (aOR=0.36; 95% CI=0.21, 0.62). Additional research is needed to understand the biologic mechanisms by which diabetes may influence prostate cancer risk; genetic factors may play an important role in understanding this association.

Association of tobacco use with hormone refractory disease and survival of patients with prostate cancer

PURPOSE

We identified time to the development of hormone refractory prostate cancer (HRPC) and survival in men with advanced prostate cancer and examined any association with cigarette smoking history.

MATERIALS AND METHODS

The study design was retrospective. A complete tobacco history was obtained in 222 patients with advanced prostate cancer. HRPC was diagnosed in 133 of these 222 patients and death occurred in 77. Standard statistical methods and software were used to analyze these data.

RESULTS

Median time to HRPC was 11, 23 and 35 months in patients with a current, former or never smoked tobacco history (p = 0.00001). Median overall survival time on androgen ablative therapy was 38, 47 and 60 months in patients with a current, former or never smoked tobacco history, respectively (p = 0.00001).

CONCLUSIONS

Tobacco use independently correlates with time to HRPC and survival in a dose dependent manner in patients with advanced prostate cancer on androgen deprivation therapy.

Diabetes mellitus and risk of prostate cancer: a meta-analysis

AIMS/HYPOTHESIS

The association of diabetes mellitus with prostate cancer has been controversial. This study examines the strength of this association by conducting a detailed meta-analysis of the studies published in peer-reviewed literature on the subject.

METHODS

A comprehensive search for articles published up to 2003 was performed, reviews of each study were conducted and data were abstracted. Prior to meta-analysis, the studies were evaluated for publication bias and heterogeneity. Pooled relative risk (RR) was calculated using the random- and the fixed-effects models. Subgroup and sensitivity analyses were also performed.

RESULTS

We included 14 studies, published between 1971 and 2002, in the meta-analysis (five case-control studies, nine cohort studies). We found no evidence of publication bias ( p=0.89) or heterogeneity among the studies ( p=0.38). The association of diabetes with prostate cancer was statistically significant, both on the basis of a random-effects model (RR=0.91, 95% CI: 0.86 to 0.96), and on the basis of a fixed-effects model (RR=0.91, 95% CI: 0.88 to 0.94). When the analysis was stratified into subgroups according to study design, the association was inverse in both cohort and case-control studies, but only in the former was it statistically significant. The sensitivity analysis strengthened our confidence in the validity of this association.

CONCLUSIONS/INTERPRETATION

Our meta-analysis findings provide strong evidence that people with diabetes have a significant decrease in risk of developing prostate cancer. There is biological evidence to support this association.

Human prostate cancer risk factors

Prostate cancer has the highest prevalence of any nonskin cancer in the human body, with similar likelihood of neoplastic foci found within the prostates of men around the world regardless of diet, occupation, lifestyle, or other factors. Essentially all men with circulating androgens will develop microscopic prostate cancer if they live long enough. This review is a contemporary and comprehensive, literature-based analysis of the putative risk factors for human prostate cancer, and the results were presented at a multidisciplinary consensus conference held in Crystal City, Virginia, in the fall of 2002. The objectives were to evaluate known environmental factors and mechanisms of prostatic carcinogenesis and to identify existing data gaps and future research needs. The review is divided into four sections, including 1) epidemiology (endogenous factors [family history, hormones, race, aging and oxidative stress] and exogenous factors [diet, environmental agents, occupation and other factors, including lifestyle factors]); 2) animal and cell culture models for prediction of human risk (rodent models, transgenic models, mouse reconstitution models, severe combined immunodeficiency syndrome mouse models, canine models, xenograft models, and cell culture models); 3) biomarkers in prostate cancer, most of which have been tested only as predictive factors for patient outcome after treatment rather than as risk factors; and 4) genotoxic and nongenotoxic mechanisms of carcinogenesis. The authors conclude that most of the data regarding risk relies, of necessity, on epidemiologic studies, but animal and cell culture models offer promise in confirming some important findings. The current understanding of biomarkers of disease and risk factors is limited. An understanding of the risk factors for prostate cancer has practical importance for public health research and policy, genetic and nutritional education and chemoprevention, and prevention strategies.

Constitutive and inducible expression of cytochromes P4501A (CYP1A1 and CYP1A2) in normal prostate and prostate cancer cells

Constitutive and benzo[a]pyrene (B[a]P) inducible expression of CYP1A1 and CYP1A2 in prostate cancer and normal prostate epithelial cells were examined by immunoblotting. Androgen independent prostate cancer cell lines DU145 and PC3 have constitutive expression of CYP1A and CYP1A1 and CYP1A2, respectively. Four micromolar B[a]P did not appear to induce CYP1A1 or CYP1A2 expression in DU145 or PC3 cells. The androgen dependent prostate cancer cell line, LnCap, also has constitutive expression of CYP1A1 and CYP1A2. However, both CYP1A1 and CYP1A2 are induced by treatment of LnCap cells with 4 microM B[a]P. Untreated normal prostate and primary prostate tumor cells have no detectable CYP1A1 expression. Treatment with 4 microM B[a]P induced CYP1A1 expression in both normal and primary tumor prostate cells. Constitutive CYP1A2 expression was detected in normal prostate cells with little or no induction by exposure to 4 microM B[a]P. Primary prostate tumor cells did not show constitutive expression of CYP1A2. However, CYP1A2 was induced by 4 microM B[a]P in primary prostate tumor cells. These observations indicate that hormonal and cancer specific factors affect the expression and induction of the phase I metabolic enzymes, CYP1A1 and CYP1A2 in prostate cells. These observations may be related to the potential smoking-linked higher risk of prostate cancer development and morbidity of prostate cancer patients who smoke.

Positive correlation between single or combined genotypes of CYP1A1 and GSTM1 in relation to prostate cancer in Chilean people

BACKGROUND

The prostate cancer is a slowly progressing disease that begins decades prior to diagnosis. It has been suggested that there might be differences in susceptibility due to genetic polymorphisms in biotransformation enzyme genes. In the present work, associations between CYP1A1(Msp1), GSTM1(-/-) polymorphisms, and prostate cancer were analyzed in a case-control study.

METHODS

Genomic DNA was isolated from peripheral blood samples, collected on EDTA. PCR-RFLP was used to determine simultaneously Msp1 and GSTM1(-/-) polymorphisms.

RESULTS

In cancer patients, frequency of m2 variant allele (0.377) and GSTM1(-/-) (0.362) showed statistically significant increases compared to the control group (0.262 and 0.227, respectively). The estimate relative risks (OR) were higher for individuals carrying combined CYP1A1 and GSTM1 rare genotypes, in relation to individuals carrying CYP1A1 or GSTM1 alone. Multivariate logistic regression analysis including confounding factors (age, digital examination, and PSA antigen) showed even higher risk for individuals carrying m2m2 genotype (OR = 3.99; 95% CI, 1.27-12.54), GST(-/-) genotype (OR = 2.75; 95% CI, 1.31-5.79), and m2m2/GST(-) genotype (OR = 16.63; 95% CI, 1.67-165.48).

CONCLUSIONS

Taken together, these findings suggest that Chilean people carrying single or combined GSTM1 and CYP1A1 polymorphisms are more susceptible to prostate cancer.

Circulating enterolactone and prostate cancer risk: a Nordic nested case-control study

Enterolactone, a phytoestrogen belonging to the class of lignans, is produced by the intestinal microflora from precursors in plant foods and has been implicated in protection against cancer. We study the effect of enterolactone on the risk of a subsequent diagnosis of prostate cancer. We conducted a longitudinal, nested case-control study by linkage of 3 biobanks to the cancer registries in Finland, Norway and Sweden, respectively. Enterolactone concentrations were measured by time-resolved fluoroimmunoassay in serum from 794 men who had a diagnosis of prostate cancer at a mean follow-up time of 14.2 years after blood collection and among 2,550 control men matched within each cohort for age (+/-2 years), date of blood collection (+/-2 months) and county. The median enterolactone concentrations did not differ between case and control subjects in the full study group (8.4 nmol/L [25th-75th percentile = 4.5-15.0] vs. 8.5 nmol/L [25th-75th percentile = 4.3-15.9]), nor in the national groups. Odds ratios of prostate cancer risk estimated by conditional logistic regression for increasing concentrations of enterolactone in quartiles in the full study group were 1.00 (referent), 1.21 (95% confidence interval [CI] = 0.96-1.52), 1.16 (95% CI = 0.91-1.47) and 1.08 (95% CI = 0.83-1.39). The OR estimate for the highest vs. the lowest quartile of enterolactone in separate analyses of the Norwegian, Finnish and Swedish cohort was 1.21 (95% CI = 0.91-1.60), 1.02 (95% CI = 0.59-1.76) and 0.87 (95% CI = 0.45-1.67), respectively. No support for the hypothesis that high circulating enterolactone is protective against prostate cancer was found.

Age, lifestyle, health risk indicators, and prostate-specific antigen scores in men participating in the world senior games

BACKGROUND

A number of risk factors have been implicated for prostate cancer, with dietary fat intake the most commonly accepted modifiable risk.

OBJECTIVE

To assess the relationship between health risk indicators (e.g., cholesterol, blood pressure, blood sugar, and percent body fat), which are related to dietary fat intake, and prostate-specific antigen (PSA) scores. Relationships between demographics and select behaviors (e.g., cigarette smoking and physical activity) with PSA scores are also considered. The setting was the 1999 Huntsman World Senior Games in St. George, Utah. Subjects' analysis is based on 536 men aged 50 years and older completing a questionnaire and receiving free screening, including a PSA.

METHODS

Frequency distributions, multiple regression techniques, and the Spearman correlation coefficients.

RESULTS

A positive relationship was observed between increasing age groups and mean PSA scores (Cochran-Mantel-Haenszel Chi-Square: 53.8, p < 0.0001). After adjusting for age, none of the personal risk factor indicators (i.e., cholesterol, blood pressure, blood sugar, and percent body fat) were related to PSA scores. Other factors not related to PSA scores after adjusting for age were race, marital status, education, history of chronic disease, cigarette smoking, alcohol use, and physical activity.

CONCLUSION

Because risk indicators such as cholesterol, blood pressure, blood sugar, and percent body fat are associated with dietary fat intake, their failure to be related with PSA scores makes it further unclear how this commonly accepted modifiable risk factor for prostate cancer may influence the disease.

Diabetes and the risk of prostate cancer

The relation between diabetes and prostate cancer risk was investigated in a combined analysis of two hospital-based case-control studies conducted in Italy and Greece, between 1985 and 1997. Cases were 608 men with incident prostate cancer, and controls were 1008 men admitted to hospital for acute non-neoplastic diseases. No material association between diabetes and prostate cancer was observed, with a multivariate odds ratio (OR) of 1.07 (95% confidence interval (CI) 0.68-1.66). Compared with men without diabetes, there was a non-significant increased risk of prostate cancer in those diagnosed with diabetes within the last 5 years (OR 2.04), while the ORs were 0.96 and 0.78 respectively for a diagnosis of diabetes 5-9 years and > or = 10 years ago.

Is obesity a risk factor for prostate cancer, and does it even matter? A hypothesis and different perspective

Measurement of obesity is not as simple as its definition. Currently, several methods of measuring obesity are used in clinical studies. Skinfold thickness, crude weight, lean body mass (LBM), body mass index (BMI), and waist-to-hip ratio (WHR) are some of the more popular methods, but each contains its inherent strengths and flaws. In general, the results of the largest studies on prostate cancer and obesity have not been conclusive. One of the largest studies found an inverse relation to prostate cancer in the youngest age groups. The age and duration of obesity or any rapid changes in weight gain, along with other unhealthy exposures, may have some relation to prostate cancer incidence and mortality. Early intrinsic or extrinsic exposure to estrogen or estrogenlike compounds may provide a protective effect. The timing and duration of a higher estrogen and/or lower testosterone exposure may have a beneficial or detrimental impact on the prognosis of an established prostate tumor. Negative exposures over time such as low levels of sex hormone-binding globulin (SHBG), a greater exposure to growth factors, elevated insulin levels, greater sympathetic activity, higher cholesterol levels, immune system dysfunction, inadequate diets, smoking status, and other factors may be associated with an increased risk of prostate cancer and other diseases. Obesity may also be associated with other cancers for similar and different reasons. For example, morbidity and mortality from postmenopausal breast cancer, colon, kidney, and other cancers are potentially associated with obesity. Other comorbidities such as cataracts, coronary heart disease, diabetes, erectile dysfunction, hypertension, and others are also associated with obesity. The 2 largest prospective studies on BMI and overall mortality have also demonstrated the substantial negative impact of excess weight on society. Prostate cancer risk and obesity need further research to establish if a true association exists, but at this time, does it really matter? Overall, the profound adverse effect of being obese on general health is dramatic, and this is what clinicians and patients need to remember.

Polymorphisms of glutathione-S-transferase genes (GSTP1, GSTM1 and GSTT1) and prostate-cancer risk

Several polymorphic glutathione-S-transferase (GST) enzymes are involved in the metabolism of a number of potential prostate carcinogens and are thought to engage in the transport of steroid hormones. A case-control study was conducted to determine the association of the GSTP1, GSTM1 and GSTT1 polymorphisms and prostate-cancer risk. The study population consisted of 166 patients with previously untreated, histologically proven prostate cancer and 166 age-matched control patients with benign prostatic hyperplasia (BPH), all of them Caucasians. In the GSTP1 gene, 2 polymorphic alleles, GSTP1*B and GSTP1*C, have been described in addition to the wild-type allele, GSTP1*A. Both polymorphic GSTP1 alleles have an A-to-G transition in exon 5, causing an isoleucine-to-valine change. The GSTP1*C allele has an additional transition from C to T. For GSTM1 as well as GSTT1, the polymorphic allele is a deletion of the gene. The proportion of individuals homozygous for the GSTP1 variant alleles (GSTP1*B/*B, GSTP1*B/*C and GSTP1*C/*C) was significantly lower in prostate-cancer patients (4.8%) than in BPH controls (14.5%), and the odds ratio (OR) was 0.24 [95% confidence interval (CI) = 0.09-0.61). The heterozygous genotypes (GSTP1*A/*B and GSTP1*A/*C) were also lower in the cancer group, though this was not significant. On the contrary, no significant effect on prostate-cancer risk was detectable for either GSTM1 (OR = 0.86, 95% CI = 0.55-1.36) or GSTT1 (OR = 0.78, 95% CI = 0.43-1.42). Of the polymorphic GSTs, GSTP1 is the most interesting candidate as a biomarker for prostate-cancer risk as we found a 76% reduced risk in men homozygous for the polymorphic GSTP1 alleles compared to those with wild-type GSTP1.

The relation of type 2 diabetes and cancer

Increasing evidence indicates that individuals with type 2 diabetes (diabetes) are at elevated risk for several common human malignancies, including cancers of the colon, breast, endometrium, pancreas, and liver. In particular, the consistent positive results reported by prospective investigations make it unlikely that methodologic issues, occult tumors, or chance results could explain the findings. Since diabetes and impaired fasting glucose together affect >25% of Americans above age 50, even a moderate etiologic association (e.g., relative risk = 1.5) would explain >10% of involved malignancies. Laboratory studies have suggested biologically plausible mechanisms. Insulin, for example, is typically at high levels during the development and early stages of diabetes. Activation of the insulin receptor by its ligand, or cross-activation of the insulin-like growth factor-I receptor, has been shown to be mitogenic and promote tumorigenesis in various model systems. A "unifying concept," in fact, holds that hyperinsulinemia may underlie the cancer associations of several additional risk factors, including high waist circumference, visceral fat, waist-to-hip ratio, body mass index, sedentary lifestyle, and energy intake. In this review, we assess current evidence regarding the relation of type 2 diabetes with cancer, and evaluate the findings in terms of well-accepted criteria for establishing causality.

Prostate cancer: how much do we know and how do we know it?

We use data from the Massachusetts Male Aging Study to approximate the total current knowledge about prostate cancer and to evaluate the relative contributions of various risk factors. The sum total of current knowledge is assessed using the area under the receiver operating characteristic curve (AUROC) and by the Hosmer-Lemeshow statistic in a logistic regression model that includes 30 risk factors identified in the literature that are available in the data set. Relative contributions are measured using the adjusted generalized R2 (AR2). To measure relative contributions, we group risk factors with similar etiology and then remove groups and compare the AR2 attained without each group to the AR2 with all variables included. The overall model fits adequately. The A UROC is 0.788, relatively far from its default value of 0.5, and the Hosmer-Lemeshow statistic has a p value of 0.926. We conclude that, while some knowledge about prostate cancer has been accumulated, there are still more risk factors yet unsuspected. The relative importance analysis shows that immutable factors (i.e. age, genotype) contribute 42%, dietary factors 30%, other lifestyle factors 15%, and endocrinological factors 11%. We recommend that age and other unchanging factors should be the primary focus of screening and risk evaluation and that future interventions should center on nutritional behavior.

Lifestyle and anthropometric risk factors for prostate cancer in a cohort of Iowa men

PURPOSE

Several lines of evidence suggest that prostate cancer has a hormonal etiology. We evaluated factors known to modulate the endocrine system, including alcohol and tobacco use, physical activity, and obesity as risk factors for prostate cancer.

METHODS

Cancer-free controls who participated in a population-based case-control study from 1986-1989 (81% response rate) were followed through 1995 for cancer incidence by linkage to the Iowa Cancer Registry; 101 incident prostate cancers were identified.

RESULTS

Compared with non-users of alcohol, men who consumed <22 grams alcohol per week (relative risk [RR] = 1.1; 95% Confidence Interval [CI] 0.6-2.1), 22-96 grams alcohol per week (RR = 2.6; 95% CI 1.4-4. 6) and >96 grams alcohol per week (RR = 3.1; 95% CI 1.5-6.3) were at increased risk of prostate cancer after adjustment for age, family history of prostate cancer, body mass index, total energy, and intake of carbohydrate, linoleic acid, lycopene, retinol, and red meat (p for trend < 0.0001). The respective RRs were similar when assessing type of alcohol consumed (beer, wine or liquor) or when well-differentiated, localized tumors were excluded. Body mass index was only weakly and positively associated with prostate cancer after adjustment for age, but this association strengthened after multivariate adjustment and exclusion of well-differentiated, localized tumors. For the latter tumors, men with a BMI of 24.1-26.6 kg/m(2) and >26.6 kg/m(2) were at elevated risk compared to men with a BMI <24.1 kg/m(2). Tobacco use (cigarettes, cigar/pipe, chewing tobacco and snuff use), height, weight, and both leisure and occupational physical activity were not associated with risk of prostate cancer in this cohort.

CONCLUSIONS

These data suggest that in white men obesity is a risk factor for more clinically significant prostate cancer and confirm limited previous reports showing that alcohol consumption is positively associated with prostate cancer and that this risk is not limited to any specific type of alcohol.

Cigarette smoking and risk of prostate cancer in the physicians' health study (United States)

To assess whether cigarette smoking is associated with prostate cancer incidence or mortality, we analyzed a large cohort of 22,071 men, aged 40-84 at baseline, in the Physicians' Health Study. During an average of 12.5 years of follow-up, we documented 996 cases of prostate cancer, including 113 fatal cases. Men were categorized according to smoking status, total pack-years smoked, and duration of smoking. We used Cox proportional hazard models to estimate the relative risks associated with smoking. Compared to never smokers, the age-adjusted relative risks (RR) of total prostate cancer were 1. 14 (95% confidence interval [CI] = 1.00-1.30) for past smokers, 1.10 (95% CI = 0.78-1.55) for current smokers of less than 20 cigarettes per day, and 1.10 (95% CI = 0.84-1.44) for current smokers of 20 or more cigarettes per day. Adjustment for body mass index, height, alcohol intake, and physical activity did not materially alter these findings. No significant association was observed in analyses of total pack-years smoked or duration of smoking. The results were similar for non-fatal and fatal prostate cancer. These data indicate no material association between cigarette smoking and prostate cancer incidence or mortality.

Second primary tumors after prostate carcinoma

BACKGROUND

Several large datasets have shown a reduced risk of all neoplasms after a diagnosis of prostate carcinoma but an increased incidence rate of urologic carcinoma has been suggested.

METHODS

Data collected by the Cancer Registries of the Swiss Cantons of Vaud and Neuchâtel (approximately 760,000 inhabitants) were used to estimate the incidence rate of a second primary tumor after a diagnosis of prostate carcinoma. A total of 4503 cases registered between 1974 and 1994 were followed until the end of 1996 (17,065 person-years).

RESULTS

A total of 380 second primary neoplasms were observed versus 534.1 expected primary neoplasms (standardized incidence ratio [SIR] = 0.7; 95% confidence interval, 0.6-0.8). SIRs were significantly below unity for lung carcinoma (SIR = 0.7) and other major tobacco-related neoplasms, including those of the mouth or pharynx (SIR = 0.5), esophagus (SIR = 0.4), pancreas (SIR = 0.5), and larynx (SIR = 0.8). There was no excess rate of subsequent urologic carcinoma (SIR = 1.0) or colorectal carcinoma (SIR = 0.9). The reduced SIRs for lung carcinoma were stronger in elderly men (age >/= 75 years) and in patients with a shorter period since diagnosis (< 5 years).

CONCLUSIONS

The incidence of all neoplasms was reduced significantly in men diagnosed with prostate carcinoma. Selection of the population, under-registration of second primary tumors, and reduced surveillance in elderly men with prostate carcinoma may, at least in part, explain this reduction in risk. No excess risk was observed for the complex of urologic neoplasms nor for tobacco-related neoplasms. This finding would not support an association between cigarette smoking and prostate carcinoma.

Smoking, plasma vitamins C, E, retinol, and carotene, and fatal prostate cancer: seventeen-year follow-up of the prospective basel study

BACKGROUND

Prostate cancer has one of the highest incidence rates of all cancers. Vitamin intake and tobacco use may have an impact on incidence and mortality, but epidemiologic evidence is scarce and inconsistent.

METHODS

Plasma vitamins C, E, retinol, and carotene were measured in 1971-1973 in 2,974 men working in Basel, Switzerland. In 1990, the vital status of all participants was assessed.

RESULTS

Two hundred and ninety men had died from cancer, including 30 with prostate cancer. On average, prostate cancer cases were 15 years older and smoked slightly more frequently than survivors. The mean values of plasma carotene, and of vitamin C, were nonsignificantly lower in prostate cancer cases than in survivors. After calculation of relative risk using the Cox model with exclusion of mortality during the first 2 years of follow-up, low vitamin E levels in smokers were related to an increased risk for prostate cancer. Relative risks of low vitamin C and carotene levels were about 1. A slightly but nonsignificantly increased risk was observed for low levels of retinol.

CONCLUSIONS

Given the profound implication if the risk of prostatic cancer could be reduced, the relationship with vitamin E and smoking requires further study.

Diet, nutrition, and prostate cancer

Cancer of the prostate gland is one of the most common malignancies in affluent nations, in part due to the application of new screening and diagnostic tools. The development of life-threatening prostate cancer is the culmination of a complex series of initiation and promotional events over a period of decades and under the influence of many interacting genetic and environmental factors. A rapidly accumulating scientific literature provides compelling evidence for the hypothesis that diet and nutrition are important factors modifying risk of prostate cancer. Additional resources devoted to interactive research efforts by laboratory scientists and epidemiologists will provide further enlightenment and continued refinement of our assessment of risks and benefits for specific nutrients and dietary patterns. These studies provide hope that evidence-based dietary interventions will significantly impact the risk of prostate cancer and enhance the efficacy of therapeutic interventions.

Smoking and urological disease

It is important to realise that virtually every part of the body, including the urological system, is adversely affected by smoking. Smoking is the most important known preventable cause of urinary bladder cancer and is also associated with a risk of prostatic and renal cancer. The exact mechanism by which smoking increases the incidence of urological malignancy is not known. One possibility is that chemicals in cigarette smoke inhibit the synthesis of cytoprotective eicosanoids. Deficient local protection, against the hostile environment caused by the presence of urine, could then encourage the process of carcinogenesis. Smoking is a powerful predictor of erectile dysfunction; cessation may restore normal function. Cigarette smoke also exerts adverse effects on sperm motility and count. Although there is no convincing evidence of reduced fertility in male smokers, it is advisable for men to quit smoking should they have marginal semen quality and wish to start a family. Smoking causes substantial urological pathology; these facts can be used to convince patients with urological problems to quit smoking.

Cigarette smoking and prostate cancer: no relation with six measures of lifetime smoking habits in a large case-control study among U.S. whites

BACKGROUND

The study was undertaken to describe the association between lifetime cigarette smoking habits and prostate cancer. Whereas most case-control and cohort studies report no association, the positive findings from some large cohort studies are difficult to ignore. The available information on lifetime smoking habits from most studies is limited however.

METHODS

In a study of 1,097 prostate cancer cases and 3,250 matched controls, admitted between 1969 and 1991 to U.S. hospitals, several ordinal measures of lifetime smoking were compared to look for dose-response or threshold associations.

RESULTS

No association was seen between prostate cancer and former or current smoking, age started smoking, number of years smoked, cigarettes per day smoked, the number of years since quitting, and lifetime tar exposure.

CONCLUSIONS

Our data provide the most complete dose-response smoking information to date, and support the findings from the majority of studies that prostate cancer is not associated with cigarette smoking.

Risk of multiple primary cancers in prostate cancer patients in the Detroit metropolitan area: a retrospective cohort study

BACKGROUND

Patterns of excess risk for second primary cancers (SPC) in prostate cancer patients have been observed for urinary bladder, other sites in the urinary tract, and hematolymphopoietic tissues in several, but not all, previously reported cohort studies.

METHODS

The risk of SPC was evaluated in 9,794 Detroit metropolitan-area men originally diagnosed with carcinoma of the prostate during 1973-1982. The cohort was assembled using Detroit Surveillance, Epidemiology, and End Results (SEER) Registry data and followed until December 31, 1993.

RESULTS

The observed number of SPC of all sites was similar to the expected number in the cohort. A significant excess of invasive SPC of the urinary bladder [Standardized incidence ratio (SIR) = 1.57; 95% CI, 1.34-1.83] was observed in this cohort, but after excluding the first 2 months after prostate cancer diagnosis, the excess (SIR = 1.06) was no longer statistically significant. The cumulative proportion of patients with prostate cancer who developed bladder cancer during a follow-up interval of 20 years was 5.5% (95% CI, 4.1-6.9%). The patients who received first-course radiation treatment were observed to be at increased risk for bladder SPC (all stages; SIR = 1.49; 95% CI, 1.07-2.02) when compared to the Detroit-area male population.

CONCLUSIONS

These results underscore the importance of continuing medical surveillance for urinary bladder second primary cancers in patients with prostate cancer, but are reassuring in that the magnitude of relative and absolute risks does not suggest deterring adverse effects of radiation treatment or intrinsic risks for neoplasms in other organs or tissues.