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2.  Associations of Circulating 25-hydroxyvitamin D with prostate cancer diagnosis, stage and grade 
Epidemiological studies suggest that vitamin D protects against prostate cancer, although evidence is limited and inconsistent. We investigated associations of circulating total 25-hydroxyvitamin D (25(OH)D) with PSA-detected prostate cancer in a case-control study nested within the Prostate Testing for Cancer and Treatment (ProtecT) trial. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) quantifying the association between circulating total 25(OH)D and prostate cancer. In case-only analyses, we used unconditional logistic regression to quantify associations of total 25(OH)D with stage (advanced vs localized) and Gleason grade (high-grade (≥7) vs low-grade (<7)). Pre-determined categories of total 25(OH)D were defined as: high: ≥30ng/mL; adequate: 20-<30ng/mL; insufficient: 12-<20ng/mL; deficient: <12ng/mL. Fractional polynomials were used to investigate the existence of any U-shaped relationship. We included 1,447 prostate cancer cases (153 advanced, 469 high-grade) and 1,449 healthy controls. There was evidence that men deficient in vitamin D had a two-fold increased risk of advanced versus localized cancer (OR for deficient vs adequate total 25(OH)D=2.33, 95% CI: 1.26,4.28) and high-grade versus low-grade cancer (OR for deficient vs adequate total 25(OH)D=1.78, 95% CI: 1.15,2.77). There was no evidence of a linear association between total 25(OH)D and prostate cancer (p=0.44) or of an increased risk of prostate cancer with high and low vitamin D levels. Our study provides evidence that lower 25(OH)D concentrations were associated with more aggressive cancers (advanced versus localized cancers and high- versus low- Gleason grade), but there was no evidence of an association with overall prostate cancer risk.
doi:10.1002/ijc.27327
PMCID: PMC3378478  PMID: 22033893
Prostate cancer; vitamin D; 25-hydroxyvitamn D
3.  Circulating insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) in PSA-detected prostate cancer: the large case control study ProtecT 
Cancer research  2011;72(2):503-515.
Circulating insulin-like growth factor-I (IGF-I) has been studied extensively in prostate cancer, but there is still little information about IGFs and IGF binding proteins (IGFBPs) in cancers detected by the prostate-specific antigen (PSA) test. Here we report the findings of a United Kingdom-based case-control study to investigate circulating IGFs and IGFBPs in PSA-detected prostate cancer with regard to their potential associations with different cancer stages or grades. PSA testing was offered to 110,000 men aged 50-69 years from 2002-2009. Participants with an elevated level of PSA (≥ 3.0 ng/ml) underwent prostate biopsy and measurements of blood serum IGF-I, IGF-II, IGFBP-2 and IGFBP-3 obtained at recruitment. We found that serum levels of IGF-II (OR per standard deviation increase: 1.16; 95%CI 1.08,1.24;ptrend<0.001), IGFBP-2 (1.18;1.06,1.31;ptrend<0.01) and IGFBP-3 (1.27;1.19,1.36;ptrend<0.001), but not IGF-I (0.99;0.93,1.04;ptrend=0.62), were associated with PSA-detected prostate cancer. After controlling for IGFBP-3, IGF-II was no longer associated (0.99;0.91,1.08;ptrend=0.62) and IGF-I was inversely associated (0.85;0.79,0.91;ptrend<0.001) with prostate cancer. In addition, no strong associations existed with cancer stage or grade. Overall, these findings suggest potentially important roles for circulating IGF-II, IGFBP-2 and IGFBP-3 in PSA-detected prostate cancer, in support of recent in vitro evidence. While our findings for IGF-I agree with previous results from PSA-screening trials, they contrast with positive associations in routinely-detected disease, suggesting that reducing levels of circulating IGF-I might not prevent the initiation of prostate cancer but might nonetheless prevent its progression.
doi:10.1158/0008-5472.CAN-11-1601
PMCID: PMC3272440  PMID: 22106399
case-control study; insulin-like growth factors; insulin-like growth factor binding proteins; prostate cancer
4.  The causal roles of vitamin B12 and transcobalamin in prostate cancer: can Mendelian randomization analysis provide definitive answers? 
Circulating vitamin B12 (cobalamin/B12) and total transcobalamin (tTC) have been associated with increased and reduced risk, respectively, of prostate cancer. Mendelian randomization has the potential to determine whether these are causal associations. We estimated associations of single nucleotide polymorphisms in B12-related genes (MTR, MTRR, FUT2, TCN2, TCN1, CUBN, and MUT) with plasma concentrations of B12, tTC, holo-transcobalamin, holo-haptocorrin, folate, and homocysteine and with prostate cancer risk in a case-control study (913 cases, 895 controls) nested within the UK-wide population-based ProtecT study of prostate cancer in men age 45-69 years. Instrumental variable (IV) analysis was used to estimate odds ratios for effects of B12 and tTC on prostate cancer. We observed that B12 was lower in men with FUT2 204G>A (rs492602), CUBN 758C>T (rs1801222) and MUT 1595G>A (rs1141321) alleles (Ptrend<0.001); tTC was lower in men with the TCN2 776C>G (rs1801198) allele (Ptrend<0.001). FUT2 204G>A and CUBN 758C>T were selected as instruments for B12; TCN2 776C>G for tTC. Conventional and IV estimates for the association of loge(B12) with prostate cancer were: OR=1.17 (95% CI 0.90-1.51), P=0.2 and OR=0.60 (0.16-2.15), P=0.4, respectively. Conventional and IV estimates for the association of loge(tTC) with prostate cancer were: OR=0.81 (0.54-1.20), P=0.3 and OR=0.41 (0.13-1.32), P=0.1, respectively. Confidence intervals around the IV estimates in our study were too wide to allow robust inference. Sample size estimates based on our data indicated that Mendelian randomization in this context requires much larger studies or multiple genetic variants that explain all of the variance in the intermediate phenotype.
PMCID: PMC3243448  PMID: 22199995
Vitamin B12/cobalamin; transcobalamin; prostate cancer; Mendelian Randomization
5.  Exploring treatment preferences facilitated recruitment to randomized controlled trials 
Journal of Clinical Epidemiology  2011;64(10):1127-1136.
Objective
To explore how patients' treatment preferences were expressed and justified during recruitment to a randomized controlled trial (RCT) and how they influenced participation and treatment decisions.
Study Design and Setting
Qualitative analysis of audio recordings of recruitment appointments with 93 participants aged 51–70 years in a UK multicenter RCT of localized prostate cancer treatments.
Results
Treatment preferences at recruitment were more complex and dynamic than previously assumed. Most participants expressed views about treatments early in appointments, ranging on a continuum from hesitant to well-formed opinions. As recruiters elicited men’s views and provided detailed evidence-based treatment and study information, some opted for their preference, but many became uncertain and open to RCT recruitment, often accepting a different treatment from their original “preference.” Discussion of treatment preferences did not act as the expected barrier to recruitment but actively enabled many to express their concerns and reach an informed decision that often included RCT participation.
Conclusion
Exploring treatment preferences and providing evidence-based information can improve levels of informed decision making and facilitate RCT participation. Treatment preferences should be reconceptualized from a barrier to recruitment to an integral part of the information exchange necessary for informed decision making about treatments and RCT participation.
doi:10.1016/j.jclinepi.2010.12.017
PMCID: PMC3167372  PMID: 21477994
Treatment preferences; Prostate cancer; ProtecT study; Qualitative research methods; Randomized controlled trial; Recruitment to RCTs
6.  Development of a New Method for Monitoring Prostate-Specific Antigen Changes in Men with Localised Prostate Cancer: A Comparison of Observational Cohorts 
European urology  2009;57(3):446-452.
Background
Prostate-specific antigen (PSA) measurements are increasingly used to monitor men with localised prostate cancer (PCa), but there is little consensus about the method to use.
Objective
To apply age-specific predictions of PSA level (developed in men without cancer) to one cohort of men with clinically identified PCa and one cohort of men with PSA-detected PCa. We hypothesise that among men with clinically identified cancer, the annual increase in PSA level would be steeper than in men with PSA-detected cancer.
Design, setting, and participants
The Scandinavian Prostatic Cancer Group 4 (SPCG-4) cohort consisted of 321 men assigned to the watchful waiting arm of the SPCG-4 trial. The UK cohort consisted of 320 men with PSA-detected PCa in the Prostate Testing for Cancer and Treatment (ProtecT) study in nine UK centres between 1999 and 2007 who opted for monitoring rather than treatment. Multilevel models describing changes in PSA level were fitted to the two cohorts, and average PSA level at age 50, change in PSA level with age, and predicted PSA values were derived.
Measurements
PSA level.
Results and limitations
In the SPCG-4 cohort, mean PSA at age 50 was similar to the cancer-free cohort but with a steeper yearly increase in PSA level (16.4% vs 4.0%). In the UK cohort, mean PSA level was higher than that in the cancer-free cohort (due to a PSA biopsy threshold of 3.0 ng/ml) but with a similar yearly increase in PSA level (4.1%). Predictions were less accurate for the SPCG-4 cohort (median observed minus predicted PSA level: −2.0 ng/ml; interquartile range [IQR]: −7.6–0.7 ng/ml) than for the UK cohort (median observed minus predicted PSA level: −0.8 ng/ml; IQR: −2.1–0.1 ng/ml).
Conclusions
In PSA-detected men, yearly change in PSA was similar to that in cancer-free men, whereas in men with symptomatic PCa, the yearly change in PSA level was considerably higher. Our method needs further evaluation but has promise for refining active monitoring protocols.
doi:10.1016/j.eururo.2009.03.023
PMCID: PMC2910432  PMID: 19303695
active surveillance; localised prostate cancer; PSA doubling time; PSA velocity; reference ranges
7.  Associations between an Obesity Related Genetic Variant (FTO rs9939609) and Prostate Cancer Risk 
PLoS ONE  2010;5(10):e13485.
Observational studies suggest that obese men have a lower risk of incident prostate cancer, but an increased risk of advanced and fatal cancers. These observations could be due to confounding, detection bias, or a biological effect of obesity. Genetic studies are less susceptible to confounding than observational epidemiology and can suggest how associations between phenotypes (such as obesity) and diseases arise. To determine whether the associations between obesity and prostate cancer are causal, we conducted a genetic association study of the relationship between a single nucleotide polymorphism known to be associated with obesity (FTO rs9939609) and prostate cancer. Data are from a population-based sample of 1550 screen-detected prostate cancers, 1815 age- and general practice matched controls with unrestricted prostate specific antigen (PSA) values and 1175 low-PSA controls (PSA <0.5 ng/ml). The rs9939609 A allele, which was associated with higher BMI in the sample, was inversely associated with overall (odds ratio (OR) versus all controls  = 0.93; 95% confidence interval (CI): 0.85–1.02 p = 0.12 per allele) and low-grade (OR = 0.90; 0.81–0.99 p = 0.03 per allele) prostate cancer risk, but positively associated with high-grade cancer among cases (OR high- versus low-grade cancer  = 1.16; 0.99–1.37 p = 0.07 per allele). Although evidence for these effects was weak, they are consistent with observational data based on BMI phenotypes and suggest that the observed association between obesity and prostate cancer is not due to confounding. Further research should confirm these findings, extend them to other BMI-related genetic variants and determine whether they are due to detection bias or obesity-related hormonal changes.
Trial Registration
Controlled-Trials.com ISRCTN20141297
doi:10.1371/journal.pone.0013485
PMCID: PMC2957440  PMID: 20976066
8.  Life course sun exposure and risk of prostate cancer: population-based nested case-control study (ProtecT) and meta-analysis 
There is currently no means of primary prevention for prostate cancer. Increased exposure to ultraviolet-radiation may be protective, but the literature is inconclusive. We investigated associations of life-course exposure to sunlight with prostate cancer. The study design was a UK-wide nested case-control study, based on 1,020 PSA-detected cases and 5,044 matched population controls and a systematic review with meta-analysis. Men with olive/brown skin (OR= 1.47; 95% CI: 1.00 to 2.17), men who burnt rarely/never (OR= 1.11; 0.95 to 1.29) and men with the lowest levels of intense sun exposure in the 2 years prior to diagnosis (OR = 1.24; 1.03 to 1.50) had an increased prostate cancer risk. However, amongst men with prostate cancer, spending less time outside was associated with a reduced risk of advanced cancer (OR = 0.49; 0.27 to 0.89) and high Gleason grade (OR = 0.62; 0.43 to 0.91), and men who burnt rarely/never had a reduced risk of advanced cancer (OR = 0.71; 0.47 to 1.08). The meta-analysis provided weak evidence that men with the lowest (versus highest) sunlight exposure had an increased prostate cancer risk (4 studies, random-effects pooled relative risk = 1.13; 0.98 to 1.29) and higher advanced or fatal prostate cancer risk (6 studies, random-effects pooled relative risk = 1.14; 0.98 to 1.33). Our data and meta-analyses provide limited support for the hypothesis that increased exposure to sunlight may reduce prostate cancer risk. The findings warrant further investigation because of their implications for vitamin D chemoprevention trials.
doi:10.1002/ijc.24411
PMCID: PMC2873563  PMID: 19444909
Prostate cancer; sun exposure; pigmentation
9.  An ecological study of prostate cancer mortality in the USA and UK, 1975-2004: are divergent trends a consequence of treatment, screening or artefact? 
The lancet oncology  2008;9(5):445-452.
Background
There is no conclusive evidence that screening based on prostate-specific antigen (PSA) tests reduces prostate cancer mortality. In the USA uptake of PSA testing has been rapid, but is much less common in the UK.
Purpose
To investigate trends in prostate cancer mortality and incidence in the USA and UK from 1975-2004, contrasting these with trends in screening and treatment.
Methods
Joinpoint regression analysis of cancer mortality statistics from Cancer Research UK and the USA National Cancer Institute Surveillance Epidemiology and End Results (SEER) program was used to estimate the annual percentage change in prostate cancer mortality in each country and the points in time when trends changed.
Results
Age-specific and age-adjusted prostate cancer mortality peaked in the early 1990s at almost identical rates in both countries, but age-adjusted mortality in the USA subsequently declined by 4.2% (95% CI 4.0-4.3%) per annum, four times the rate of decline in the UK (1.1%; 0.8-1.4%). The mortality decline in the USA was greatest and most sustained in those ≥75 years, whereas death rates had plateaued in this age group in the UK by 2000.
Conclusion
The striking decline in prostate cancer mortality in the USA compared with the UK between 1994-2004 coincided with much higher uptake of PSA screening in the USA. Explanations for the different trends in mortality include the possibility of an early impact of initial screening rounds on men with more aggressive asymptomatic disease in the USA, different approaches to treatment in the two countries, and bias related to the misattribution of cause of death. Speculation over the role of screening will continue until evidence from randomised controlled trials is published.
doi:10.1016/S1470-2045(08)70104-9
PMCID: PMC2760747  PMID: 18424233
Prostate Cancer Mortality; Prostate Cancer Screening; Prostate Cancer Treatment
10.  Detection of prostate cancer in unselected young men: prospective cohort nested within a randomised controlled trial  
BMJ : British Medical Journal  2007;335(7630):1139.
Objective To investigate the feasibility of testing for prostate cancer and the prevalence and characteristics of the disease in unselected young men.
Design Prospective cohort nested within a randomised controlled trial, with two years of follow-up.
Setting Eight general practices in a UK city.
Participants 1299 unselected men aged 45-49.
Intervention Prostate biopsies for participants with a prostate specific antigen level of 1.5 ng/ml or more and the possibility of randomisation to three treatments for those with localised prostate cancer.
Main outcome measures Uptake of testing for prostate specific antigen; positive predictive value of prostate specific antigen; and prevalence of prostate cancer, TNM disease stage, and histological grade (Gleason score).
Results 442 of 1299 men agreed to be tested for prostate specific antigen (34%) and 54 (12%) had a raised level. The positive predictive value for prostate specific antigen was 21.3%. Ten cases of prostate cancer were detected (2.3%) with eight having at least two positive results in biopsy cores and three showing perineural invasion. One tumour was of high volume (cT2c), Gleason score 7, with a positive result on digital rectal examination; nine tumours were cT1c, Gleason score 6, and eight had a negative result on digital rectal examination. Five of the nine eligible participants (55%) agreed to be randomised. No biochemical disease progression in the form of a rising prostate specific antigen level occurred in two years of follow-up.
Conclusions Men younger than 50 will accept testing for prostate cancer but at a much lower rate than older men. Using an age based threshold of 1.5 ng/ml, the prevalence of prostate cancer was similar to that in older men (3.0 ng/ml threshold) and some cancers of potential clinical significance were found.
Trial registration Current Controlled Trials ISRCTN20141297
doi:10.1136/bmj.39381.436829.BE
PMCID: PMC2099560  PMID: 18006969
11.  Impact of Helicobacter pylori eradication on dyspepsia, health resource use, and quality of life in the Bristol helicobacter project: randomised controlled trial 
BMJ : British Medical Journal  2006;332(7535):199-204.
Objective To determine the impact of a community based Helicobacter pylori screening and eradication programme on the incidence of dyspepsia, resource use, and quality of life, including a cost consequences analysis.
Design H pylori screening programme followed by randomised placebo controlled trial of eradication.
Setting Seven general practices in southwest England.
Participants 10 537 unselected people aged 20-59 years were screened for H pylori infection (13C urea breath test); 1558 of the 1636 participants who tested positive were randomised to H pylori eradication treatment or placebo, and 1539 (99%) were followed up for two years.
Intervention Ranitidine bismuth citrate 400 mg and clarithromycin 500 mg twice daily for two weeks or placebo.
Main outcome measures Primary care consultation rates for dyspepsia (defined as epigastric pain) two years after randomisation, with secondary outcomes of dyspepsia symptoms, resource use, NHS costs, and quality of life.
Results In the eradication group, 35% fewer participants consulted for dyspepsia over two years compared with the placebo group (55/787 v 78/771; odds ratio 0.65, 95% confidence interval 0.46 to 0.94; P = 0.021; number needed to treat 30) and 29% fewer participants had regular symptoms (odds ratio 0.71, 0.56 to 0.90; P = 0.05). NHS costs were £84.70 (£74.90 to £93.91) greater per participant in the eradication group over two years, of which £83.40 ($146; €121) was the cost of eradication treatment. No difference in quality of life existed between the two groups.
Conclusions Community screening and eradication of H pylori is feasible in the general population and led to significant reductions in the number of people who consulted for dyspepsia and had symptoms two years after treatment. These benefits have to be balanced against the costs of eradication treatment, so a targeted eradication strategy in dyspeptic patients may be preferable.
doi:10.1136/bmj.38702.662546.55
PMCID: PMC1352048  PMID: 16428249
12.  Randomised controlled trial of effects of Helicobacter pylori infection and its eradication on heartburn and gastro-oesophageal reflux: Bristol helicobacter project 
BMJ : British Medical Journal  2004;328(7453):1417.
Objectives To investigate the effects of Helicobacter pylori infection and its eradication on heartburn and gastro-oesophageal reflux.
Design Cross sectional study, followed by a randomised placebo controlled trial.
Setting Seven general practices in Bristol, England.
Participants 10 537 people, aged 20-59 years, with and without H pylori infection (determined by the 13C-urea breath test).
Main outcome measures Prevalence of heartburn and gastro-oesophageal acid reflux at baseline and two years after treatment to eradicate H pylori infection.
Results At baseline, H pylori infection was associated with increased prevalence of heartburn (odds ratio 1.14, 95% confidence interval 1.05 to 1.23) but not reflux (1.05, 0.97 to 1.14). In participants with H pylori infection, active treatment had no effect on the overall prevalence of heartburn (0.99, 0.88 to 1.12) or reflux (1.04, 0.91 to 1.19) and did not improve pre-existing symptoms of heartburn or reflux.
Conclusions H pylori infection is associated with a slightly increased prevalence of heartburn but not reflux. Treatment to eradicate H pylori has no net benefit in patients with heartburn or gastro-oesophageal reflux.
doi:10.1136/bmj.38082.626725.EE
PMCID: PMC421785  PMID: 15126313
14.  Short term outcomes of prostate biopsy in men tested for cancer by prostate specific antigen: prospective evaluation within ProtecT study 
Objectives To measure the effect of the adverse events within 35 days of transrectal ultrasound guided biopsy from the perspective of asymptomatic men having prostate specific antigen (PSA) testing; to assess early attitude to re-biopsy; to estimate healthcare resource use associated with adverse events due to biopsy; and to develop a classification scheme for reporting adverse events after prostate biopsy.
Design Prospective cohort study (Prostate Biopsy Effects: ProBE) nested within Prostate Testing for Cancer and Treatment (ProtecT) study.
Participants Between 1999 and 2008, 227 000 community dwelling men aged 50­69 years were identified at 352 practices and invited to counselling about PSA testing. 111 148 attended a nurse led clinic in the community, and 10 297 with PSA concentrations of 3-20 ng/mL were offered biopsy within ProtecT. Between February 2006 and May 2008, 1147/1753 (65%) eligible men (mean age 62.1 years, mean PSA 5.4 ng/mL) having 10 core transrectal ultrasound guided biopsy under antibiotic cover in the context of ProtecT were recruited to the ProBE study.
Outcome measures Purpose designed questionnaire administered at biopsy and 7 and 35 days after the procedure to measure frequency and effect of symptoms related to pain, infection, and bleeding; patients’ attitude to repeat biopsy assessed immediately after biopsy and 7 days later; participants’ healthcare resource use within 35 days of biopsy evaluated by questionnaire, telephone follow-up, and medical note review; each man’s adverse event profile graded according to symptoms and healthcare use.
Results Pain was reported by 429/984 (43.6%), fever by 172/985 (17.5%), haematuria by 642/976 (65.8%), haematochezia by 356/967 (36.8%), and haemoejaculate by 605/653 (92.6%) men during the 35 days after biopsy. Fewer men rated these symptoms as a major/moderate problem—71/977 (7.3%) for pain, 54/981 (5.5%) for fever, 59/958 (6.2%) for haematuria, 24/951 (2.5%) for haematochezia, and 172/646 (26.6%) for haemoejaculate. Immediately after biopsy, 124/1142 (10.9%, 95% confidence interval 9.2 to 12.8) men reported that they would consider further biopsy a major or moderate problem: seven days after biopsy, this proportion had increased to 213/1085 (19.6%, 17.4% to 22.1%). A negative attitude to repeat biopsy was associated with unfavourable experience after the first biopsy, particularly pain at biopsy (odds ratio 8.2, P<0.001) and symptoms related to infection (7.9, P<0.001) and bleeding (4.2, P<0.001); differences were evident between centres (P<0.001). 119/1147 (10.4%, 8.7% to 12.3%) men reported consultation with a healthcare professional (usually their general practitioner), most commonly for infective symptoms. Complete data for all index symptoms at all time points were available in 851 participants. Symptoms and healthcare use could be used to grade these men as follows: grade 0 (no symptoms/contact) 18 (2.1%, 1.3% to 3.3%); grade 1 (minor problem/no contact) 550 (64.6%, 61.4% to 67.8%); grade 2 (moderate/major problem or contact) 271 (31.8%, 28.8% to 35.1%); grade 3 (hospital admission) 12 (1.4%, 0.8% to 2.4%); and grade 4 (death) 0. Grade of adverse event was associated with an unfavourable attitude to repeat biopsy (Kendall’s τ-b ordinal by ordinal 0.29, P<0.001).
Conclusion This study with a high response rate of 89% at 35 days in men undergoing biopsy in the context of a randomised controlled trial has shown that although prostate biopsy is well tolerated by most men, it is associated with significant symptoms in a minority and affects attitudes to repeat biopsy and primary care resource use. These findings will inform men who seek PSA testing for detection of prostate cancer and assist their physicians during counselling about the potential risks and effect of biopsy. Variability in the adverse event profile between centres suggests that patients’ outcomes could be improved and healthcare use reduced with more effective administration of local anaesthetic and antibiotics.
Trial registration Current Controlled Trials ISRCTN20141297.
doi:10.1136/bmj.d7894
PMCID: PMC3253765  PMID: 22232535
15.  Circulating folate, vitamin B12, homocysteine, vitamin B12 transport proteins and risk of prostate cancer: a case-control study, systematic review and meta-analysis 
Background
Disturbed folate metabolism is associated with an increased risk of some cancers. Our objective was to determine whether blood levels of folate, vitamin B12 and related metabolites were associated with prostate cancer risk.
Methods
Matched case-control study nested within the UK population-based ProtecT study of PSA-detected prostate cancer in men aged 50–69 years. Plasma concentrations of folate, B12 (cobalamin), holo-haptocorrin, holo- and total-transcobalamin, and total homocysteine (tHcy) were measured in 1,461 cases and 1,507 controls. ProtecT study estimates for associations of folate, B12, and tHcy with prostate cancer risk were included in a meta-analysis, based on a systematic review.
Results
In the ProtecT study, increased B12 and holo-haptocorrin concentrations showed positive associations with prostate cancer risk (highest vs lowest quartile of B12 odds ratio (OR)=1.17 (95% CI 0.95–1.43), P-for-trend=0.06; highest vs lowest quartile of holo-haptocorrin OR=1.27 (1.04–1.56), P-for-trend=0.01); folate, holo-transcobalamin and tHcy were not associated with prostate cancer risk. In the meta-analysis, circulating B12 levels were associated with an increased prostate cancer risk (pooled OR=1.10 (1.01–1.19) per 100 pmol/L increase in B12, P=0.002); the pooled OR for the association of folate with prostate cancer was positive (OR=1.11 (0.96–1.28) per 10 nmol/L, P=0.2) and conventionally statistically significant if ProtecT (the only case-control study) was excluded (OR=1.18 (1.00–1.40) per 10 nmol/L, P=0.02).
Conclusion
Vitamin B12 and (in cohort studies) folate were associated with increased prostate cancer risk.
Impact
Given current controversies over mandatory fortification, further research is needed to determine whether these are causal associations.
doi:10.1158/1055-9965.EPI-10-0180
PMCID: PMC3759018  PMID: 20501771
folate; vitamin B12; cobalamin; transcobalamin; haptocorrin; homocysteine; folate-mediated one-carbon metabolism; prostate cancer

Results 1-15 (15)