Clinical Trial Details
— Status: Recruiting
Administrative data
NCT number |
NCT02759380 |
Other study ID # |
410-14 |
Secondary ID |
|
Status |
Recruiting |
Phase |
N/A
|
First received |
|
Last updated |
|
Start date |
March 2016 |
Est. completion date |
December 2024 |
Study information
Verified date |
January 2023 |
Source |
Sahlgrenska University Hospital, Sweden |
Contact |
Maria Hedelin, P.hD |
Phone |
+4670-7401858 |
Email |
maria.hedelin[@]oncology.gu.se |
Is FDA regulated |
No |
Health authority |
|
Study type |
Interventional
|
Clinical Trial Summary
The purpose of this study is to evaluate if a diet with a high content of phytoestrogens can
slow down the prostate tumor proliferation. Phytoestrogens are found in food items such as
soy, rye, and seeds.
Two hundred thirty men with prostate cancer will be included in the study and followed until
surgery (at least 6 weeks). Half of the study participants will receive general information
about healthy food choices and a package of foods with high content of phytoestrogens to add
to their food. The other half will get the same information but not receive the food-package.
Description:
Data from ecologic and experimental studies clearly show a protective effect of dietary
phytoestrogens against prostate cancer. Genetic factors are also of etiologic importance in
prostate cancer and there is growing evidence for the importance of a gene-diet interaction
in prostate cancer progression. The investigators have recently found a putative genetic
interaction for this protective role of phytoestrogens. The overall decreased risk of
prostate cancer in men with a high intake of phytoestrogens was strongly modified by a
nucleotide sequence variant in the estrogen receptor-beta (ERß) gene. An American study found
a similar interactive effect between intake of phytoestrogens, as well as body mass index
(BMI), and another nucleotide sequence variant in ERß.The phytoestrogens isoflavonoids and
coumestans bind tightly to the estrogen receptor-beta (ERß) and are mainly found in soy and
other beans. ERß expression has been found to be involved in progression of prostate cancer,
suggesting that phytoestrogens may interact with ERß in the development of prostate cancer.
With regard to potential carcinogenic mechanisms, phytoestrogens may be involved in the
endocrine control of prostate cell growth by influencing the balance between AR and
ERß.Testosterone and its metabolite 5α-dihydrotestosterone (DHT) cause proliferation of
prostate epithelial cells through binding to the AR. In contrast, by binding to ERß, 5α
androstane-3ß,17ß-diol (3ßAdiol), a metabolite of DHT, represses the expression of AR and
thereby inhibits androgen-driven proliferation while promoting cell differentiation. In terms
of proliferation, current data suggests a combined stimulatory role of ERα and AR in the
prostate whereas ERß inhibits proliferation and stimulates differentiation. Both estrogen ERα
and ß have affinity for estradiol whereas phytoestrogens and 3ßAdiol selectively activate
ERß. Phytoestrogens should, as a result, be able to restrict cancer growth by acting as a
substitute for 3ßAdiol. This is confirmed by experimental studies.
Results from previous intervention studies have given promising results indicating that
certain dietary or lifestyle modifications can influence the progression of prostate cancer,
although most of these studies have been of fairly short of duration and based on relatively
small numbers of patients. For example, a randomised study showed that men who were given a
dietary addition of flaxseeds had a lower percentage of positive cells containing the
proliferation marker Ki-67 than men who had not received this addition to their diet. Taken
together, the present evidence points towards the possibility for prostate cancer patients to
complement with lifestyle-related treatment alternatives to prevent or delay tumor
progression.
Specific aim: To perform a controlled randomized dietary intervention study in men with
prostate cancer. The investigators will pursue the following specific aims/hypothesis:
1. "Among men with prostate cancer of intermediate risk-level, a diet high in
phytoestrogens will reduce tumor progression compared to men with a diet low in
phytoestrogens".
2. "The effects of a diet high in phytoestrogens on prostate cancer tumor progression
differ between men with different genotypes of polymorphisms in the ERß gene". The men
will be divided into two subgroups, those bearing TT or TC/CC alleles, of the
single-nucleotide polymorphism (SNP) rs2987983-13950 T/C in the ERß-gene, in which the
hypothesis will be tested.
3. To determine whether RNA expression of the AR, ERα and ERβ in prostate tumor tissue, as
well as levels of steroid hormones, differs between men with a diet high and low in
phytoestrogens, respectively, or between different genotypes of the ERβ gene.
4. To determine whether mRNA expression of genes involved in proliferation and ER signal
pathways analyzed by whole transcriptomic profiling in prostatectomy specimens differs
between men with a diet high and low in phytoestrogens, respectively, or between
different genotypes of the ERβ gene.
Study protocol: Trough treating physicians, the investigators will identify 240 men in the
Västra Götaland healthcare region who have been diagnosed with prostate cancer of
intermediate risk-level (T1-T2, Gleason score <8, PSA<20)scheduled for radical prostatectomy.
The clinic will be informed of which patients have been enrolled in the study, and the
surgery for these patients will be scheduled six weeks ahead of time from the date of
inclusion. Once a patient has agreed to participate, he will be randomized to one of the two
intervention arms. The patient will then receive additional information depending on which
group he belongs to and will be asked to donate a blood sample. Under normal clinical
routine, data on all prostate cancer cases is collected in the National Prostate Cancer
Register (NPCR), for example information on Gleason score, tumor volume, Prostate-specific
antigen (PSA) levels. The investigators will collect information from the registry in
connection with the analysis of data.
Intervention: Patients will be introduced to the intervention diet by a dietitian and will
receive general information about healthy food choices (according to recommendations for the
general public) and not to eat any dietary supplements, no other dietary restrictions will be
given. The patients will be given a package containing food with a high amount of
phytoestrogens (≥100 mg isoflavonoids and ≥100 mg lignans) that are to be consumed daily. The
intervention continues until the day before the surgery (at least 6 weeks). The patients in
the control group will be informed in the same way as the intervention group except that they
will not receive any food-package.
Endpoint: The effect of the diet on tumor proliferation rate will be measured by making
comparisons of 1) percentage of positive cells containing the marker Ki-67, 2) PSA-levels, 3)
expression of genes involved in proliferation and ER signal pathways and cell-cycle
progression (CCP) gene expression. In immediate adjacency to the surgery, the surgeon
collects four median-needle biopsies from the fresh prostate specimen, two from the tumor
site and two from healthy prostate tissue, based on previous results from the diagnostic
biopsies and magnetic resonance imaging.Also at the surgery, the radical prostatectomy
tissues are collected and formalin fixed paraffin embedded. Blood samples will be taken at
the beginning of the study, at the day before the surgery, and send to analysis of PSA (free
and total). The absolute differences in PSA levels and the PSA doubling time will be
calculated. In addition the investigators will measure the expression of AR, ERα and ERß in
tumor tissue and the blood levels of hormones, testosterone, DHT, estradiol and 3ß-Adiol.
Questionnaire: All patients will answer a password-protected questionnaire at baseline,
surgery, weight and height will be measured. Once during the 6-weeks period a 24-h recall
interview will be performed, in which participants food intake during the preceding 24 h will
be registered. The individual intake of energy and specific nutrients will be estimated by
linking information from the questionnaire and diet record to the National Food Agency's
nutritional database and our previously developed phytoestrogen database. Information on the
possible use of Finasteride, a 5α-reductase inhibitor, will be collected from medical
records.
Concentrations of phytoestrogens in blood: In a proportion of participants, plasma
concentrations of different phytoestrogens (daidzein, enterodiol, enterolactone, equol,
genistein, glycetein, lariciresinol, and secoisolariciresinol) will be analyzed, using
LC-MS/MS measurements performed on microLC 200 series (Eksigent/AB Sciex, Redwood City, CA,
USA) and QTrap 5500 mass spectrometer (AB Sciex, Framingham, MA, USA).
Analysis of polymorphs:SNP in the ERß-gene will be analysed in blood samples, using the
PCR-based method competitive allele specific PCR (KASP™). The allele-constitution will be
identified and participants will be assigned to group TT, TC or CC. Analysis of Ki-67: The
biopsy sample is fixed by immersion with 4 % paraformaldehyde in 0,1 M phosphate buffer
during 24hours at +4°C. Then it is dehydrated with graded ethanol followed by xylene and
paraffin embedding. Paraffin sections are heated for 30 minutes at 60ºC, pre-treated with
citric acid buffer. Unspecific binding is blocked by donkey serum in phosphate buffered
saline (PBS) containing Triton X-100 for 30 minutes. Incubating with Ki-67 antibody over
night (4ºC) followed by incubation with the appropriate secondary biotinylated antibody. To
enhance the signal, the sections are treated with avidin-biotin-complex solution, and to
visualize the immunoreactivity Diaminobenzidine (DAB) is used. Stained tumor cells (Ki-67
positivity) will be counted and the result will be reported as the ratio of positive nuclei
divided by the total number evaluated × 100.
Analysis of receptor-expression, CCP score, hormone levels and PSA: Tissue samples taken at
surgery is placed in RNA-later before being frozen. The samples will be analysed using RNeasy
plus Universal Mini Kits (QIAGEN), and Real-time polymerase chain reaction (PCR). ERα, ERβ
and AR mRNA expression will be determined using TaqMan assay. Total RNA will be extracted
from formalin-fixed paraffin-embedded sections of tumors and benign tissues using the global
transcriptome-wide expression array Clariom ™ D (Thermos Fischer). For analysis of the CCP
score, gene expression of the genes involved in CCP based on the Prolaris® gene panel and the
Decipher Score, respectively.. PSA-blood levels will be analysed according to standard
clinical protocol.
Power calculation: In the Västra Götaland healthcare region in 2012, 321 men had intermediate
risk-level prostate cancer for which they received curative treatment. Calculation using the
primary outcome (Ki-67) gives for a study group consisting of 118 patients an 80 % power for
a two-sided test with a level of significance at 0,05 and effect size of 0,5. The
investigators found in earlier studies that approximately 42 % of the male population are
heterozygous or homozygous for the variant allele (TC/CC) of the ERβ promoter region SNP
(rs2987983-13950 T/C) and 58 % homozygous for the wild type allele (TT). Since the
investigators expect the effect of the intervention to be greater among subjects with the
variant allele, while smaller among subjects with the wild type allele, this latter group
ought to be large enough to be able to find a difference if one exists. Thus a total sample
size of 118/58%=203 patients is needed.
Statistical Considerations: The investigators will utilize the intention-to-treat method. In
the design and data collection testing of drugs as the template have been made
(randomization, placebo, blinding, no attrition, no differential measuring errors, correct
analysis); for the deviations from the perfect situation the investigators use
epidemiological theory for guiding the analyses and interpreting the results. Preliminary
analyses, based on means, medians, standard deviations and interquantile range will be
provided to properly describe the outcomes of interest and stratification will be performed
to assess the performance of the randomization of the assigned diet. Box-plots will therefore
be produced to graphically evaluate the temporal trends in the response. The distribution of
the outcomes will be studied and appropriate transformations will be applied, if needed, to
improve symmetry and normality. Due to the longitudinal structure of the data, correlation
among observations will be incorporated and linear mixed effects models will be carried out
to study if (i) there is a temporal trend (ii) if the linear trend differs between treated
and untreated individuals (iii) if the treatment effect between the intervention group and
the control group is modified according to ERß genotypes, both for the common and the
variant. A key step in analysis of longitudinal data is to identify the appropriate
covariance structure that describes the correlations among the data points: independent
covariance (no correlation), exchangeable covariance (equal correlation) or autoregressive
covariance with correlation between responses decreasing with time between measurements. The
investigators will identify the most appropriate structure, verified empirically with help of
an information theoretic approach. Both statistical tests and confidence intervals will be
produced to assess the significance of the effects, partial F test procedures will therefore
be used to study the joined effect of main and interaction variables and appropriate
statistical methods will be applied to study model fitting. The association between
phytoestrogens intake and cancer proliferation will be evaluated by generalized linear
models, which will provide estimates of the risk difference (RDs) and corresponding 95% CIs,
stratified by ERβ genotypes. Interactions between phytoestrogen intake and ERβ SNPs on
proliferation will be evaluated considering additive effect scales. Group of phytoestrogen
intake are included as a continuous variable, and each SNP are represented by an indicator
variable (variant or not). Interaction will be assessed in a linear odds model by the product
term between the covariates representing phytoestrogen intake and SNP genotypes.