Body mass index in relation to serum prostate-specific antigen levels and prostate cancer risk

Obesity, the Adipose Organ and Cancer in Humans: Association or Causation?

Epidemiological observations, experimental studies and clinical data show that obesity is associated with a higher risk of developing different types of cancer; however, proof of a cause-effect relationship that meets the causality criteria is still lacking. Several data suggest that the adipose organ could be the protagonist in this crosstalk. In particular, the adipose tissue (AT) alterations occurring in obesity parallel some tumour behaviours, such as their theoretically unlimited expandability, infiltration capacity, angiogenesis regulation, local and systemic inflammation and changes to the immunometabolism and secretome. Moreover, AT and cancer share similar morpho-functional units which regulate tissue expansion: the adiponiche and tumour-niche, respectively. Through direct and indirect interactions involving different cellular types and molecular mechanisms, the obesity-altered adiponiche contributes to cancer development, progression, metastasis and chemoresistance. Moreover, modifications to the gut microbiome and circadian rhythm disruption also play important roles. Clinical studies clearly demonstrate that weight loss is associated with a decreased risk of developing obesity-related cancers, matching the reverse-causality criteria and providing a causality correlation between the two variables. Here, we provide an overview of the methodological, epidemiological and pathophysiological aspects, with a special focus on clinical implications for cancer risk and prognosis and potential therapeutic interventions.

Family history, obesity, urological factors and diabetic medications and their associations with risk of prostate cancer diagnosis in a large prospective study

Background

Prostate cancer (PC) aetiology is unclear. PC risk was examined in relation to several factors in a large population-based prospective study.

Methods

Male participants were from Sax Institute’s 45 and Up Study (Australia) recruited between 2006 and 2009. Questionnaire and linked administrative health data from the Centre for Health Record Linkage and Services Australia were used to identify incident PC, healthcare utilisations, Prostate Specific Antigen (PSA) testing reimbursements and dispensing of metformin and benign prostatic hyperplasia (BPH) prescriptions. Multivariable Cox and Joint Cox regression analyses were used to examine associations by cancer spread, adjusting for various confounders.

Results

Of 107,706 eligible men, 4257 developed incident PC up to end 2013. Risk of PC diagnosis increased with: PC family history (versus no family history of cancer; HR_adjusted = 1.36; 95% CI:1.21–1.52); father and brother(s) diagnosed with PC (versus cancer-free family history; HR_adjusted = 2.20; 95% CI:1.61–2.99); severe lower-urinary-tract symptoms (versus mild; HR_adjusted = 1.77; 95% CI:1.53–2.04) and vasectomy (versus none; HR_adjusted = 1.08; 95% CI:1.00–1.16). PC risk decreased with dispensed prescriptions (versus none) for BPH (HR_adjusted = 0.76; 95% CI:0.69–0.85) and metformin (HR_adjusted = 0.57; 95% CI:0.48–0.68). Advanced PC risk increased with vasectomy (HR_adjusted = 1.28; 95% CI:1.06–1.55) and being obese (versus normal weight; HR_adjusted = 1.31; 95% CI:1.01–1.69).

Conclusion

Vasectomy and obesity are associated with an increased risk of advanced PC. The reduced risk of localised and advanced PC associated with BPH, and diabetes prescriptions warrants investigation.

Contributions of Social Factors to Disparities in Prostate Cancer Risk Profiles among Black Men and Non-Hispanic White Men with Prostate Cancer in California

BACKGROUND

Black men are more likely than Non-Hispanic White (NHW) men to be diagnosed with high-risk prostate cancer. We examined the extent to which social factors were associated with differences in prostate cancer risk profiles between Black men and NHW men [using a modification to the original D'Amico risk groups based on prostate specific antigen (PSA), Gleason score (GS), and TNM stage (stage)], based on individual and combined clinicopathologic characteristics.

METHODS

We conducted a cross-sectional population-based study of 23,555 Black men and 146,889 NHW men diagnosed with prostate cancer in the California Cancer Registry from 2004 to 2017. We conducted multivariable logistic regression to examine the association of year of diagnosis, block group-level neighborhood socioeconomic status (nSES), marital status, and insurance type on differences in prostate cancer risk profiles between Black and NHW men.

RESULTS

High PSA (>20 ng/mL), GS, stage, individually and combined prostate cancer risk profiles were more common among Black men versus NHW men. In fully adjusted models, relative to NHW men, we observed a persistent 67% increased odds of high PSA among Black men. nSES was the factor most strongly associated with racial disparity in high PSA, accounting for 25% of the difference. Marital status was the factor that was second most associated with a racial disparity.

CONCLUSIONS

nSES was the factor most strongly associated with racial disparities in high PSA prostate cancer.

IMPACT

The influence of nSES on racial disparities in PSA, GS, stage, and prostate cancer risk profiles warrants further consideration.

Body mass index in relation to prostate-specific antigen-related parameters

Background

Only a few previous studies conducted to assess the association between body mass index (BMI) and prostate-specific antigen (PSA) related parameters have taken prostate volume (PV) and blood volume (BV) into consideration. The objective of this study was to assess the relationship between BMI and parameters of PSA concentrations in Chinese adult men.

Methods

A total of 86,912 men who have received annual physical examination at the First Affiliated Hospital of Army Medical University from 1 January 2011 to 31 December 2018 were included in this study. Linear regression models were performed to assess the relationship between BMI, PV, BV and PSA, and analyze the correlation between BMI and PSA, PSA density and PSA mass.

Results

The univariable linear regression showed that PV, BV, systolic pressure (SBP), pulse, fasting blood glucose (FBG) and age were significantly associated with PSA level (P < 0.05). The multivariate linear regression demonstrated that PV, BV, FBG and age were significantly associated with PSA level (P < 0.05). WHR and BMI is negatively associated with PSA and PSA density (P < 0.05), and no statistically significant association was found between PSA mass and WHR and (P = 0.268) or BMI (P = 0.608).

Conclusions

The findings of this large-sample, hospital-based study in China indicate that PV was positively associated with serum PSA concentrations, while BMI and BV were inversely related with PSA levels. PSA mass can be used to estimate the PSA concentration without being affected by obesity in Chinese men.

PSA and obesity among men with localized prostate cancer: results of the ANDROCAN study

PURPOSE

PSA is known to be lowered in obese patients. There is a lack of data regarding patients with prostate cancer. Our objective was to prospectively assess the relationship PSA concentration, PSA mass and BMI in a cohort of patients with localized prostate cancer.

METHODS

A prospective, multicenter cohort study was conducted including patients undergoing radical prostatectomy. Clinical and biological data were collected for each patient before surgery.

RESULTS

A total of 1343 patients were analyzed. Mean age was 64.0 years. Mean weight was 82.2 kg and mean BMI was 26.8 kg/m². Mean PSA concentration was 8.7 ng/mL and mean PSA mass 29.3 ng. On univariate analysis, an association was found between PSA mass and either BMI, weight and waist circumference. No association was found between PSA concentration and each weight parameters. On multivariate analysis, obesity was not an independent predictor of PSA concentration (p = 0.73). Independent predictors of PSA concentration were cardiovascular disease (negative association, p = 0.034), predominant Gleason 4 (positive association, p < 0.001) and pT3a (positive association, p < 0.001). BMI was an independent predictor of PSA mass (positive association, p = 0.009). PSA mass was negatively associated with TT (p = 0.015) and cardiovascular disease (p = 0.003), and positively associated with BT (p = 0.032), Gleason grade ≥ 4 + 3 (p < 0.001) and pT3a (p < 0.001).

CONCLUSION

In this prospective study of patients with localized prostate cancer, higher BMI was associated with higher PSA mass but not with higher PSA concentration. Screening obese patients with a specific PSA method does not appear to be critical.

Tobacco and marijuana use and their association with serum prostate-specific antigen levels among African American men in Chicago

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AA men are under-represented in PSA research, a biomarker of prostate cancer aggresiveness.

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Cigarette smoking was associated with an increase in PSA among older AA men.

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Tobacco use was associated with an increase in PSA among older AA men.

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Marijuana use was associated with a decrease in PSA among older AA men.

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Future behavioral risk factor studies linked to biopsy outcomes are warranted.

African American (AA) men experience more than twice the prostate cancer mortality as White men yet are under-represented in academic research involving prostate-specific antigen (PSA), a biomarker of prostate cancer aggressiveness. We examined the impact of self-reported tobacco (cigarette pack-years and current tobacco use including e-cigarettes) and current regular marijuana use on serum PSA level based on clinical laboratory testing among 928 AA men interviewed 2013–2018 in Chicago. We defined outcome of elevated PSA ≥ 4.0 ng/mL for logistic regression models and continuous PSA increases for general linear models. All models were adjusted for age, sociodemographic characteristics, healthcare utilization, body mass index, and self-reported health. Among 431 AA men age ≥ 55 years, we observed ∼ 5 times the odds of elevated PSA among those with > 1 pack-years of cigarette smoking vs. never-smokers (odds ratio [OR] = 5.09; 95% confidence interval [CI] = 1.57–16.6) and a quarter the odds of elevated PSA among current marijuana users vs. non-users (OR = 0.27; 95% CI = 0.08–0.96). PSA increased on average 1.20 ng/mL among other current tobacco users vs. non-users. Among older AA men, cigarette smoking history and current tobacco use were positively associated with an increase in PSA levels and current marijuana use were inversely associated with PSA levels. Future work with studies of diverse patient populations with cancer outcomes are needed to assess whether these behavioral characteristics contribute to racial/ ethnic disparities in prostate cancer outcomes. Our study provides novel evidence regarding potential differences in PSA levels among older AA men according to behavioral characteristics.

Association of obesity status and metabolic syndrome with site-specific cancers: a population-based cohort study

Background

Obesity and metabolic syndrome (MetS) appear in clusters and are both associated with an increased risk of cancer. However, it remains unknown whether obesity status with or without MetS increases the risk of site-specific cancers.

Methods

We used data derived from 390,575 individuals (37–73 years old) from the UK Biobank who were enrolled from 2006–2016 with a median of 7.8 years of follow-up. Obesity was defined by BMI ≥ 30 kg/m² and MetS was defined by the criteria of the Adult Treatment Panel-III (ATP-III). Cox proportional hazards models were used to investigate the associations of BMI and MetS with 22 cancers.

Results

Metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) phenotypes represented 6.7% and 17.9% of the total analytic samples and 27.1% and 72.9% of the included subpopulation with obesity, respectively. Obesity was independently associated with higher risks of 10 of 22 cancers. Stratified by metabolic status, the MUO phenotype was consistently associated with 10 obesity-related cancers. In contrast, the MHO phenotype was only associated with increased risks of five cancers: endometrium, oesophagus, kidney, pancreas and postmenopausal breast cancers.

Conclusion

Even in metabolically healthy individuals, obesity was associated with increased risks of five cancers, whereas we did not find that these individuals were associated with increased risks of several other obesity-related cancers.

Systematic review and meta-analysis of the associations between body mass index, prostate cancer, advanced prostate cancer, and prostate-specific antigen

PURPOSE

The relationship between body mass index (BMI) and prostate cancer remains unclear. However, there is an inverse association between BMI and prostate-specific antigen (PSA), used for prostate cancer screening. We conducted this review to estimate the associations between BMI and (1) prostate cancer, (2) advanced prostate cancer, and (3) PSA.

METHODS

We searched PubMed and Embase for studies until 02 October 2017 and obtained individual participant data from four studies. In total, 78 studies were identified for the association between BMI and prostate cancer, 21 for BMI and advanced prostate cancer, and 35 for BMI and PSA. We performed random-effects meta-analysis of linear associations of log-PSA and prostate cancer with BMI and, to examine potential non-linearity, of associations between categories of BMI and each outcome.

RESULTS

In the meta-analyses with continuous BMI, a 5 kg/m2 increase in BMI was associated with a percentage change in PSA of - 5.88% (95% CI - 6.87 to - 4.87). Using BMI categories, compared to normal weight men the PSA levels of overweight men were 3.43% lower (95% CI - 5.57 to - 1.23), and obese men were 12.9% lower (95% CI - 15.2 to - 10.7). Prostate cancer and advanced prostate cancer analyses showed little or no evidence associations.

CONCLUSION

There is little or no evidence of an association between BMI and risk of prostate cancer or advanced prostate cancer, and strong evidence of an inverse and non-linear association between BMI and PSA. The association between BMI and prostate cancer is likely biased if missed diagnoses are not considered.

All-cancer incidence in Tehranian adults: more than a decade of follow-up-results from the Tehran Lipid and Glucose Study

OBJECTIVES

To investigate the incidence rates for different malignancies and assess the risk factors for all-cancer incidence in Tehran.

STUDY DESIGN

Cohort study.

METHODS

This study consists of 8599 participants aged ≥ 30 years who were free of cancer (3935 men). Cancer diagnosis was based on pathology reports. Sex-stratified crude incidence rates and age-standardized incidence rates (ASRs) using Segi's method were calculated for all-cancers. Multivariate Poisson regression models were used to evaluate associations of potential risk factors, including sex, age, obesity status (body mass index [BMI]: 25-30 kg/m² as reference), education, smoking status, and diabetes mellitus with the incidence of cancers among the population. Incidence rate ratios (IRRs) with 95% confidence interval (CI) were also reported.

RESULTS

During a median follow-up of 13.9 years, there were 130 and 129 incident cancers for men and women, respectively; the corresponding ASRs were 356.1 and 243.6 per 100,000 person-years, respectively. The three most incident cancers among men were gastrointestinal (GI) (ASR = 127.5), hematopoietic (ASR = 99.5), and reproductive system malignancies (ASR = 46.3). The most common incident cancers in women were breast cancer (ASR = 92.1), GI (ASR = 65.4), and reproductive system malignancies (ASR = 16.8). Among risk factors for cancer incidence, age (IRR [95% CI]: 1.05 [1.03-1.06]) and having a BMI < 25 kg/m² (IRR [95% CI]: 1.38 [1.01-1.90]) had a statistically significant association with incident cancer.

CONCLUSIONS

The high rates of cancers in Tehran during more than a decade of follow-up calls for a need to define risk factors as well as to implement programs for early screening.

A Comprehensive Genome-Wide and Phenome-Wide Examination of BMI and Obesity in a Northern Nevadan Cohort

The aggregation of Electronic Health Records (EHR) and personalized genetics leads to powerful discoveries relevant to population health. Here we perform genome-wide association studies (GWAS) and accompanying phenome-wide association studies (PheWAS) to validate phenotype-genotype associations of BMI, and to a greater extent, severe Class 2 obesity, using comprehensive diagnostic and clinical data from the EHR database of our cohort. Three GWASs of 500,000 variants on the Illumina platform of 6,645 Healthy Nevada participants identified several published and novel variants that affect BMI and obesity. Each GWAS was followed with two independent PheWASs to examine associations between extensive phenotypes (incidence of diagnoses, condition, or disease), significant SNPs, BMI, and incidence of extreme obesity. The first GWAS examines associations with BMI in a cohort with no type 2 diabetics, focusing exclusively on BMI. The second GWAS examines associations with BMI in a cohort that includes type 2 diabetics. In the second GWAS, type 2 diabetes is a comorbidity, and thus becomes a covariate in the statistical model. The intersection of significant variants of these two studies is surprising. The third GWAS is a case vs. control study, with cases defined as extremely obese (Class 2 or 3 obesity), and controls defined as participants with BMI between 18.5 and 25. This last GWAS identifies strong associations with extreme obesity, including established variants in the FTO and NEGR1 genes, as well as loci not yet linked to obesity. The PheWASs validate published associations between BMI and extreme obesity and incidence of specific diagnoses and conditions, yet also highlight novel links. This study emphasizes the importance of our extensive longitudinal EHR database to validate known associations and identify putative novel links with BMI and obesity.

Night shiftwork and prostate-specific antigen level in a tire manufacturing factory

BACKGROUND

Recent studies suggest that night shiftwork may increase the risk of prostate cancer and elevated serum prostate-specific antigen (PSA) level. The purpose of this study was to verify whether rotating night shiftwork affects serum PSA level.

METHODS

This study included 3,195 male production workers who work in a large tire manufacturing factory. Serum PSA levels were measured and the data on related factors were obtained.

RESULTS

The mean serum PSA level was 0.98 ± 0.79 ng/mL. PSA levels were significantly lower in the younger age group, the obese group, and regular exercise group. PSA levels were lower in night shift workers (n = 2,832) compared to day workers (n = 363), but the difference was not statistically significant.

CONCLUSIONS

Unlike previous studies, we did not find any evidence that night shiftwork results in an increase in serum PSA levels. Further research and consistent results are needed to elucidate the association between night shiftwork and the effect on the prostate.

Altered circulating levels of adipokine omentin-1 in patients with prostate cancer

Background: Prostate cancer (PCa), one of the most common cancers in men, accounts for nearly 20% of adult malignant neoplasms. Omentin-1 is synthesized in visceral adipose tissue and its concentration in plasma changes with cancers. However, the association between omentin-1 and PCa was rarely studied. Thus, we investigated the plasma omentin-1 levels in PCa patients in Chinese population.

Materials and methods: Ninety cases of PCa and 90 matched healthy controls were enrolled in this study. We used ELISA technique to determine the concentration of omentin-1.

Results: The concentration of omentin-1 was higher in patients with PCa compared to controls (P<0.001). Additionally, positive correlations were uncovered between omentin-1 with body mass index (r=0.240, P=0.001), waist-hip ratio (r=0.228, P=0.002), and prostate-specific antigen (r=0.589, P<0.001). Receiver operating characteristic curve analysis indicated that plasma omentin-1 differentiated PCa patients from controls with a sensitivity of 85.9% and a specificity of 83.7%.

Conclusion: Our study demonstrated that the levels of plasma omentin-1 were increased in PCa patients. Meanwhile, omentin-1 may be a possible biomarker for diagnosing PCa. For validation, more studies should focus on and elucidate the potential mechanism underlying this change.

The inverse relationship between prostate specific antigen (PSA) and obesity

Obese men have lower serum prostate-specific antigen (PSA) than comparably aged lean men, but the underlying mechanism remains unclear. The aim of this study was to determine the effect of obesity on PSA and the potential contributing mechanisms. A cohort of 1195 men aged 35 years and over at recruitment, with demographic, anthropometric (BMI, waist circumference (WC)) and serum hormone (serum testosterone, estradiol (E2)) PSA and hematology assessments obtained over two waves was assessed. Men with a history of prostate cancer or missing PSA were excluded, leaving 970 men for the final analysis. Mixed-effects regressions and mediation analyses adjusting for hormonal and volumetric factors explore the potential mechanisms relating obesity to PSA. After adjusting for age, PSA levels were lower in men with greater WC (P = 0.001). In a multivariable model including WC, age, E2/testosterone and PlasV as predictors, no statistically significant associations were observed between with PSA and either WC (P = 0.36) or PlasV (P = 0.49), while strong associations were observed with both E2/testosterone (P < 0.001) and age (P < 0.001). In the mediation analyses with PlasV as the mediator, the average causal mediation effect (ACME) explained roughly 20% of the total effect of WC on PSA (P = 0.31), while when E2/testosterone is a mediator, the ACME explained roughly 50% of the effect (P < 0.001). Our findings indicate that lower PSA levels in obese men, as compared to normal weight men, can be explained both by hormonal changes (elevated E2/testosterone ratio) and hemodilution. Hormonal factors therefore represent a substantial but underappreciated mediating pathway.

BMI trajectories and risk of overall and grade-specific prostate cancer: An observational cohort study among men seen for prostatic conditions

Background

Dynamic longitudinal patterns in body mass index (BMI) have been suggested to better predict health outcomes than static measures. Effects of BMI trajectories on prostate cancer (PCa) risk have not been thoroughly explored.

Methods

Cohort data were derived from electronic medical records of patients who were admitted to a tertiary‐care hospital in the Southeastern USA during 1994‐2016. Patients with a history of urologic clinic visit because of any prostatic condition and with repeatedly measured BMI (n = 4857) were included. BMI trajectories prior to PCa diagnosis were assessed using the developmental trajectory analysis method. Cox proportional hazards regression modeling was used to estimate adjusted hazard ratio (aHR) with 95% confidence intervals (CIs) for overall and grade‐specific PCa.

Results

The median age (interquartile range, IQR) of the participants at baseline was 63 (54, 72) years. Over a median follow‐up (IQR) of 8.0 (2.0, 13.0) years, 714 (14.7%, 714/4857) were diagnosed with PCa. Men with growing BMI trajectory progressing from normal weight to overweight/obese had a 76% increased PCa risk (aHR = 1.76; 95% CI: 1.25, 2.48), and men being obese and experiencing progressive weight gain had 3.72‐fold increased PCa risk (aHR = 3.72; 95% CI: 1.60, 8.66), compared to men with persistently normal BMI. The associations were more pronounced for PCa with Gleason score ≥7. No significant association of decreasing BMI trajectory progressing from obese to normal BMI was found with PCa risk.

Conclusions

Progressively body weight gain during middle‐to‐late adulthood was associated with increased PCa risk for both normal weight and overweight men. Further studies are warranted to confirm this finding.

Obesity and prostate cancer

PURPOSE OF REVIEW

To investigate the association between obesity and prostate cancer (PCa).

RECENT FINDINGS

Obesity has been proposed to be involved in the pathogenesis of PCa through different biological mechanisms that include deregulation of the insulin axis, sex hormone secretion, adipokines signaling, and oxidative stress. Hypertrophic peritumoral adipocytes may also facilitate the local spread of PCa through the chemo-attraction of tumor cells. Clinical studies demonstrate that obesity might have clinical implications also in disease detection and management. Obese men have been shown to be less likely to be diagnosed with early-stage disease. Moreover, they are at increased risk of experiencing upgrading and upstaging when managed with active surveillance. However, the association between obesity and the risk of PCa recurrence and mortality after radical treatment is still debated.

SUMMARY

Obesity may facilitate the development and progression of PCa trough different biologic mechanisms that may pose obese men at higher risk of advanced and high-grade disease. However, the association between obesity and long-term oncologic outcome after radical treatments appears unclear.

Correlation between body mass index (BMI) and the Gleason score of prostate biopsies in Chinese population

We assessed the correlation between BMI and Gleason score in prostate biopsies in Chinese Population. In this retrospective study, we collected the Gleason score, PSA, BMI, age, race, and other related clinical data on 290 patients who had undergone prostatic biopsy. We then compared the prostate cancer detection rates and Gleason scores between the high BMI group (BMI ≥ 25; 143 cases) and low BMI group (< 25; 147 cases). Among the 137 patients in whom prostate cancer detected, 70 had high BMIs and 67 had normal BMIs, making the detection rates 48.95% and 45.58% respectively. Seventeen prostate cancer patients had low Gleason scores (Gleason score < 7), while 120 had high Gleason scores (≥ 7). Within the high BMI group, 44.76% had high Gleason scores, which was significantly greater than the 38.10% in the low BMI group (P = 0.027). These results indicate that while there was no effect of BMI on the rate of positive prostate cancer biopsies, the rate of high Gleason scores was greater in the high BMI group than the normal BMI group.

The influence of nutritional factors on prostate cancer incidence and aggressiveness

There is an increasing evidence for a link between nutrition, lifestyle and prostate cancer (PCa) development and/or progression of disease. The objective of this study was to examine the association between dietary factors and PCa incidence and aggressiveness in a case-control study. After the analysis of the anatomic pathology, subjects were classified in patients with PCa (n = 157) and controls (n = 158). Clinical data including Gleason score, PSA values and biopsy results, were compiled. Frequencies of food consumption and sociodemographic data were also obtained. The results showed that physical activity was significantly higher in control (p < .022). It was also found that some nutritional habits offer a protective effect among studied subjects, like high nuts (p = .041) and fish (p = .041) intakes. Moreover, there was a significant reduction in risk (p = .029) in cases with a higher fruits and vegetables intakes. A decreased risk of aggressive PCa was associated with fruits, vegetables, legumes and fish intakes. However, these relationships were not statistically significant when data were adjusted for covariates. In conclusion, this study found an inverse association between PCa risk and the intake of fruits and vegetables, fish and nuts. The results suggested that a diet with higher intakes of these foods as Mediterranean diet may lower the risk of PCa in the studied population. As dietary factors are modifiable, identifying food groups or dietary patterns that modulate the risk of PCa and its aggressiveness can offer effective and practical strategies for its primary prevention.

Prospective investigation of risk factors for prostate cancer in the UK Biobank cohort study

BACKGROUND

Prostate cancer is the most common cancer in British men but its aetiology is not well understood. We aimed to identify risk factors for prostate cancer in British males.

METHODS

We studied 219 335 men from the UK Biobank study who were free from cancer at baseline. Exposure data were collected at recruitment. Prostate cancer risk by the different exposures was estimated using multivariable-adjusted Cox proportional hazards models.

RESULTS

In all, 4575 incident cases of prostate cancer occurred during 5.6 years of follow-up. Prostate cancer risk was positively associated with the following: black ethnicity (hazard ratio black vs white=2.61, 95% confidence interval=2.10-3.24); having ever had a prostate-specific antigen test (1.31, 1.23-1.40); being diagnosed with an enlarged prostate (1.54, 1.38-1.71); and having a family history of prostate cancer (1.94, 1.77-2.13). Conversely, Asian ethnicity (Asian vs white hazard ratio=0.62, 0.47-0.83), excess adiposity (body mass index (⩾35 vs <25 kg m-2=0.75, 0.64-0.88) and body fat (⩾30.1 vs <20.5%=0.81, 0.73-0.89)), cigarette smoking (current vs never smokers=0.85, 0.77-0.95), having diabetes (0.70, 0.62-0.80), and never having had children (0.89, 0.81-0.97) or sexual intercourse (0.53, 0.33-0.84) were related to a lower risk.

CONCLUSIONS

In this new large British prospective study, we identified associations with already-established, putative and possible novel risk factors for being diagnosed with prostate cancer. Future research will examine associations by tumour characteristics.

Diet, Physical Activity, and Body Weight in Cancer Survivorship

Diet, physical activity, and body weight have been shown to play an important role in cancer survivorship. The impact of each of these lifestyle factors differs slightly among cancer types, and adherence to recommended diet and physical activity guidelines has been associated with positive outcomes, including decrease in the risk of cancer recurrence and improvement of quality of life. Although there are compelling data that appropriate diet, physical activity, and body weight have beneficial effects in cancer survivorship, additional trials are needed to understand the relationship.

Body mass index and incidence of nonaggressive and aggressive prostate cancer: a dose-response meta-analysis of cohort studies

The relationship between body mass index (BMI) and incidence of prostate cancer is still inconclusive. We performed a dose-response meta-analysis of eligible cohort studies to evaluate potential association of BMI with prostate cancer risk by subtype of prostate cancer (nonaggressive and aggressive). A comprehensive literature search was performed in PubMed and Web of Science databases through March 22, 2017. Linear and non-linear dose-response meta-analyses were carried out to evaluate the effects of BMI on incidence of prostate cancer. A total of 21 cohort or nested case-control studies (17 for nonaggressive and 21 for aggressive prostate cancer) were included in this meta-analysis. For nonaggressive prostate cancer, the pooled relative risk (RR) per 5 kg/m² increment of BMI with 95% confidence interval (CI) was 0.96 (95% CI 0.92–1.00). Sensitivity analysis indicated that this result was not robust and steady. For aggressive prostate cancer, a significant linear direct relationship with BMI (RR, 1.07; 95% CI 1.03–1.12) for every 5 kg/m2 increase was observed. Statistically significant heterogeneity was detected for nonaggressive prostate cancer (P = 0.020, I² = 46.1%) but not for aggressive prostate cancer (P = 0.174, I² = 22.4%). In conclusion, BMI level may be positively associated with aggressive prostate cancer risk. Further large prospective cohort studies are warranted to confirm the findings from our study.