This is an observational single-center trial for patients with localized prostate cancer suitable for High Dose Rate (HDR) brachytherapy as monotherapy. This study takes a multi-omics approach to study the mechanism of action of HDR brachytherapy through metabolomics, immunological, transcriptomics, and spectroscopic profiling. The results of this study will clarify the optimal dose for HDR prostate brachytherapy by documenting the dose-response relationship seen in the changing tumor metabolites after HDR brachytherapy and investigate the immunogenicity of HDR brachytherapy.
Favorable risk and intermediate-risk prostate cancer with estimated life expectancy of at least 10 years.
Clinical stage T1c-T2b, PSA < 20, Gleason < 8
ECOG 0-1
Low tier intermediate-risk prostate cancer is defined by: a single NCCN intermediate risk factor (either Gleason 7(3+4) and PSA < 10 ng/ml OR Gleason 6 and PSA 10-20 ng/ml)
Prior radical surgery for carcinoma of the prostate,
Prior pelvic radiation
Prior chemotherapy for prostate cancer,
Claustrophobic or unable to undergo MRI
Patients diagnosed with localized prostate cancer suitable for brachytherapy as monotherapy.
Cohort
Prospective
High dose rate prostate brachytherapy
RadiationTemporary implantation of radioactive material into the prostate in the form of a stepping source of Iridium 192 that travels through 16-18 needles or catheters strategically placed through the prostate.
Changes in biomolecular composition in prostate cancer after high dose rate prostate brachytherapy as measured by Raman spectroscopy
We will report the most important biomolecules altered by radiation (importance determined by the relative change of the score as a component of the Raman spectrum before and after radiation) and whether that observed change corelates with PSA outcome for each individual patient
ctDNA detection following HDR Brachytherapy
Number of patients with a (transient) increase in circulating tumor DNA after a single fraction of high-dose rate prostate brachytherapy will be reported
Immunogenicity against somatic mutations
single cell-RNA sequencing of immune cell populations before and after 13.5 Gray of radiation will be used for each individual patient and the number of patients with a change in gene expression (through activation or inactivation) will be reported
Gut microbiome
To determine microbial composition before brachytherapy and report for the individual patient whether diversity in composition is changed or skewed after treatment with high dose rate prostate brachytherapy. Second assessment is after completion of both fractions of radiation. Number of patients with alteration in microbial composition will be reported.
Response Outcome: PSA Nadir
PSA recorded every 3 months to 12 months, every 6 months to 3 years, and annually to 10 years
Response Outcome: 4-year PSA
4-year PSA \< 0.2 ng/ml (indicative of cure)
Acute and long term toxicity
Acute and long-term toxicity will be graded using the Common Terminology Criteria for Adverse Events (CTCAE V5) at each follow up time point
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British Columbia Cancer Agency
Lead sponsor
BC Cancer Foundation
Collaborator
University of British Columbia
Collaborator
Vancouver Prostate Centre
Collaborator
