ORCID Profile
0000-0001-5904-2684
Current Organisations
University of Adelaide
,
University of Melbourne
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Publisher: American Society of Clinical Oncology (ASCO)
Date: 11-2021
DOI: 10.1200/PO.20.00337
Abstract: Androgen receptor (AR) signaling is important in prostate cancer progression, and therapies that target this pathway have been the mainstay of treatment for advanced disease for over 70 years. Tumors eventually progress despite castration through a number of well-characterized mechanisms however, little is known about what determines the magnitude of response to short-term pathway inhibition. We evaluated a novel combination of AR-targeting therapies (degarelix, abiraterone, and bicalutamide) and noted that the objective patient response to therapy was highly variable. To investigate what was driving treatment resistance in poorly responding patients, as a secondary outcome we comprehensively characterized pre- and post-treatment s les using both whole-genome and RNA sequencing. We find that resistance following short-term treatment differs molecularly from typical progressive castration-resistant disease, associated with transcriptional reprogramming, to a transitional epithelial-to-mesenchymal transition (EMT) phenotype rather than an upregulation of AR signaling. Unexpectedly, tolerance to therapy appears to be the default state, with treatment response correlating with the prevalence of tumor cells deficient for SNAI2, a key regulator of EMT reprogramming. We show that EMT characterizes acutely resistant prostate tumors and that deletion of SNAI2, a key transcriptional regulator of EMT, correlates with clinical response.
Publisher: Springer Science and Business Media LLC
Date: 09-06-2021
DOI: 10.1038/S41391-021-00379-4
Abstract: Recent publications have shown patients with defects in the DNA mismatch repair (MMR) pathway driven by either MSH2 or MSH6 loss experience a significant increase in the incidence of prostate cancer. Moreover, this increased incidence of prostate cancer is accompanied by rapid disease progression and poor clinical outcomes. We show that androgen-receptor activation, a key driver of prostate carcinogenesis, can disrupt the MSH2 gene in prostate cancer. We screened tumours from two cohorts (recurrent/non-recurrent) of prostate cancer patients to confirm the loss of MSH2 protein expression and identified decreased MSH2 expression in recurrent cases. Stratifying the independent TCGA prostate cancer cohort for MSH2/6 expression revealed that patients with lower levels of MSH2/6 had significant worse outcomes, in contrast, endometrial and colorectal cancer patients with lower MSH2/6 levels. MMRd endometrial and colorectal tumours showed the expected increase in mutational burden, microsatellite instability and enhanced immune cell mobilisation but this was not evident in prostate tumours. We have shown that loss or reduced levels of MSH2/MSH6 protein in prostate cancer is associated with poor outcome. However, our data indicate that this is not associated with a statistically significant increase in mutational burden, microsatellite instability or immune cell mobilisation in a cohort of primary prostate cancers.
Publisher: Springer Science and Business Media LLC
Date: 22-07-2021
DOI: 10.1186/S12885-021-08529-6
Abstract: Prostate cancer is caused by genomic aberrations in normal epithelial cells, however clinical translation of findings from analyses of cancer cells alone has been very limited. A deeper understanding of the tumour microenvironment is needed to identify the key drivers of disease progression and reveal novel therapeutic opportunities. In this study, the experimental enrichment of selected cell-types, the development of a Bayesian inference model for continuous differential transcript abundance, and multiplex immunohistochemistry permitted us to define the transcriptional landscape of the prostate cancer microenvironment along the disease progression axis. An important role of monocytes and macrophages in prostate cancer progression and disease recurrence was uncovered, supported by both transcriptional landscape findings and by differential tissue composition analyses. These findings were corroborated and validated by spatial analyses at the single-cell level using multiplex immunohistochemistry. This study advances our knowledge concerning the role of monocyte-derived recruitment in primary prostate cancer, and supports their key role in disease progression, patient survival and prostate microenvironment immune modulation.
Publisher: Bioscientifica
Date: 05-2019
DOI: 10.1530/EC-19-0029
Abstract: Prostate cancer is a leading cause of morbidity and cancer-related death worldwide. Androgen deprivation therapy (ADT) is the cornerstone of management for advanced disease. The use of these therapies is associated with multiple side effects, including metabolic syndrome and truncal obesity. At the same time, obesity has been associated with both prostate cancer development and disease progression, linked to its effects on chronic inflammation at a tissue level. The connection between ADT, obesity, inflammation and prostate cancer progression is well established in clinical settings however, an understanding of the changes in adipose tissue at the molecular level induced by castration therapies is missing. Here, we investigated the transcriptional changes in periprostatic fat tissue induced by profound ADT in a group of patients with high-risk tumours compared to a matching untreated cohort. We find that the deprivation of androgen is associated with a pro-inflammatory and obesity-like adipose tissue microenvironment. This study suggests that the beneficial effect of therapies based on androgen deprivation may be partially counteracted by metabolic and inflammatory side effects in the adipose tissue surrounding the prostate.
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 12-2013
Publisher: Elsevier BV
Date: 10-2014
Publisher: Wiley
Date: 28-04-2022
DOI: 10.1111/ANS.17713
Abstract: To evaluate the role of in-bore MRI-guided biopsy (IB-MRGB) in the diagnosis of clinically significant prostate cancer (csPCa). In this tertiary single centre study, a total of 125 consecutive patients receiving IB-MRGB over a three-year period were evaluated, including 73 patients who had prior biopsies and 52 biopsy-naïve patients. We assessed cancer detection rate of patients according to the degree of suspicion based on mpMRI findings. Histopathological data were reviewed by experienced uropathologists. The mpMRI was suspicious for PCa (PI-RADS 4/5) in 77% (96/125) and equivocal (PI-RADS 3) in 23% (29/125). The detection rate for csPCa was 54.2% (52/96) and 20.7% (6/29) for suspicious lesions (PI-RADS 4/5) and equivocal lesions (PI-RADS 3), respectively. In subgroup analysis, patients with previous negative biopsy, overall positive biopsy rate and csPCa detection rate were 48.3% (19/35) and 34.5% (13/35), respectively. In patients on AS, 36/44 (81.8%) and 21/44 (47.8%) had PCa and csPCa respectively. In biopsy-naïve patients 34/52 (65.4%) and 27/52 (51.92%) had PCa and csPCa respectively. Of the patients on AS, 18/44 (41.6%) upgraded from ISUP 1 to ISUP 2 PCa, and 4/44 (9.1%) upgraded from ISUP 1 to ISUP 3 PCa on IB-MRGB. A total of 14 Clavien-Dindo≤2 complications occurred in 14 patients (11.2%) that were directly related to the biopsy. No Clavien-Dindo≥3 complications occurred. MRI-targeted biopsy is suitable for assessment of csPCa. Given the favourable complications profile, its use may be considered in both the initial biopsy and re-biopsy settings.
Publisher: Bioscientifica
Date: 05-2018
DOI: 10.1530/ERC-17-0466
Abstract: Obesity is linked with more aggressive prostate cancer and higher rates of disease recurrence post treatment. It is unclear if this is due to specific tumor-promoting effects of obesity or diagnostic bias. Patients undergoing prostatectomy were categorized according to their body mass index (BMI). Expected prostate-specific antigen (PSA) levels were calculated for each patient based on tumor characteristics. The effect of obesity on the accuracy of pre-treatment risk categorization was determined, and mediation analysis was used to identify the contribution of biologic vs non-biologic mechanisms to the observed increased risk of biochemical recurrence. Residual tumor-promoting effects were estimated in a survival model controlling for diagnostic error. The following results were obtained. The analysis included 1587 patients. Despite similar rates of adverse pathological features at prostatectomy, biochemical recurrence rates were significantly higher in very obese patients, which persisted after adjustment for stage, grade and PSA. Tumor volume however correlated significantly with BMI ( P = 0.004), and the difference in predicted and observed ‘tumor-attributable’ PSA (Delta-PSA) in very obese patients was greater than three times higher than that of healthy patients ( P = 0.0067). Regression analysis indicated that the effect of BMI on tumor volume was fully mediated indirectly by its effect on PSA. Inclusion of this diagnostic error as a covariate in the survival analysis attenuated the effect of BMI on recurrence. In conclusion, being very obese suppresses tumor-associated PSA resulting in a diagnostic bias that is responsible for errors in risk classification, and potentially contributes to a delay in initial presentation.
Publisher: Springer Science and Business Media LLC
Date: 31-10-2018
DOI: 10.1007/S00345-018-2542-X
Abstract: To review the current understanding and recent developments regarding the concept of oligometastases in hormone-sensitive prostate cancer. A comprehensive literature search of electronic databases, including PubMed and Embase was conducted for the search term 'oligometastases' in combinations with 'prostate cancer', 'hormone sensitive', 'genetics', and 'molecular'. All articles relating to these search terms have been taken into account. Prostate cancer remains a major cause of morbidity and mortality worldwide. The majority of these cancer-related deaths result from metastases. Currently, there is a dichotomy in prostate cancer management where it is only deemed curable if it is localized, while any signs of metastasis relegate patients to systemic therapies to delay their inevitable death. A growing body of evidence supports the notion that aggressive treatments during the stable 'oligometastatic' state can have significant clinical benefits and potentially 'reset' prostate cancer to an earlier time point in cancer progression. This concept of oligometastases has been adopted in other cancer settings such as colorectal and non-small-cell lung cancers. Multiple clinical and molecular biological studies have been influential in the support of a stable state in metastatic cancer progression coined 'oligometastases'. As our understanding of oligometastases in hormone-sensitive prostate cancer develops, we will be able to molecularly define the oligometastatic state and develop clinically available diagnostic tests. In doing so, prostate cancer patients will experience significant clinical benefits and the burden of prostate cancer worldwide will likely be reduced.
Publisher: Elsevier BV
Date: 05-2021
Publisher: Wiley
Date: 04-06-2021
DOI: 10.1002/BCO2.99
Abstract: To investigate the utility of Magnetic Resonance Imaging (MRI) for prostate cancer diagnosis in the Australian setting. All consecutive men who underwent a prostate biopsy (transperineal or transrectal) at Royal Melbourne Hospital between July 2017 to June 2019 were included, totalling 332 patients. Data were retrospectively collected from patient records. For each in idual patient, the risk of prostate cancer diagnosis at biopsy based on clinical findings was determined using the European Randomized study of Screening for Prostate Cancer (ERSPC) risk calculator, with and without incorporation of MRI findings. MRI has good diagnostic accuracy for clinically significant prostate cancer. A PI‐RADS 2 or lower finding has a negative predictive value of 96% for clinically significant cancer, and a PI‐RADS 3, 4 or 5 MRI scan has a sensitivity of 93%. However, MRI has a false negative rate of 6.5% overall for clinically significant prostate cancers. Pre‐ biopsy MRI may reduce the number of unnecessary biopsies, as up to 50.0% of negative or ISUP1 biopsies have MRI PI‐RADS 2 or lower. Incorporation of MRI findings into the ERSPC calculator improved predictive performance for all prostate cancer diagnoses (AUC 0.77 vs 0.71, P = .04), but not for clinically significant cancer (AUC 0.89 vs 0.87, P = .37). MRI has good sensitivity and negative predictive value for clinically significant prostate cancers. It is useful as a pre‐biopsy tool and can be used to significantly reduce the number of unnecessary prostate biopsies. However, MRI does not significantly improve risk predictions for clinically significant cancers when incorporated into the ERSPC risk calculator.
Publisher: Wiley
Date: 2021
DOI: 10.1002/BCO2.60
Publisher: Wiley
Date: 19-10-2019
DOI: 10.1111/BJU.14556
Abstract: To characterise the pattern of late biochemical recurrence (BCR) in the largest contemporary cohort of patients with localised prostate cancer treated with radical prostatectomy (RP) in the active surveillance era. Consecutive patients who underwent RP for localised prostate cancer between 2003 and 2017 were identified from a prospectively recorded, dedicated prostate cancer database. Patients who received neoadjuvant androgen-deprivation therapy were excluded. These patients were categorised into the following groups: no BCR, BCR at 60 months (late), after RP. Clinicopathological characteristics were analysed using the Student's t-test, Mann-Whitney U-test, or chi-squared test where appropriate. Multivariable binomial logistic regression models were used to assess predictors of BCR at various time-points. In all, 2312 patients were included in the final analysis with up to 12 years of follow-up data. The average patient had clinically localised prostate cancer, an elevated PSA level, and International Society of Urological Pathology (ISUP) Grade Group 2 on biopsy. In all, 88.7% of patients had ISUP Grade Group ≥2 at RP. A subgroup of 446 patients had undetectable PSA levels at 5 years after RP 11.7% of them progressed to experience BCR. In this subgroup, late recurrers had significantly higher-grade tumours on ISUP and Gleason sum (P <0.001 and P = 0.001, respectively), higher rates of extraprostatic extension (P = 0.022), and larger tumour volumes (P = 0.032). Logistic regression showed that RP ISUP Grade Group was a significant predictor of BCR (odds ratio 2.14, 95% confidence interval 1.43-3.20 P <0.001). This study characterises the pattern of late BCR in the largest contemporary active surveillance era cohort. We have identified that RP ISUP Grade Group is a strong predictive indicator for late BCR. We also propose that timing of BCR resides on a continuum of risk and that the potential concept of dormant micrometastatic involvement requires further research and evaluation.
Publisher: Wiley
Date: 08-01-2018
DOI: 10.1111/ANS.14361
Abstract: The aim of this study was to describe our initial Australian single surgeon experience with robotic-assisted radical cystectomy (RARC) and intracorporeal urinary ersion (ICUD) and to compare the outcomes with open radical cystectomy (ORC). Between January 2014 and June 2016, consecutive patients diagnosed with muscle invasive and high-risk non-muscle invasive bladder cancer undergoing radical cystectomy were included. Treatment modalities included either RARC with ICUD or ORC. ICUD consisted of either intracorporeal ileal conduit or orthotopic neobladder formation. Prospectively collected perioperative and oncological outcomes were analysed. Twenty-six RARC and 13 ORC were performed. Median operating times were 362 and 240 min for RARC and ORC, respectively (P < 0.001). Estimated blood loss for RARC was 300 mL compared with 500 mL for ORC (P = 0.01). Post-operative haemoglobin drop was less in the RARC cohort (20% versus 24%, P = 0.03). There was no statistical difference in overall 90-day complication rates (81% versus 62%, P = 0.25) and 90-day major complication rates (19% versus 23%, P = 0.67) between the RARC and ORC groups, respectively. Positive surgical margins for RARC were 4% and 8% for ORC (P = 1.0). Early results demonstrate that the safe introduction of RARC with ICUD in Australia is potentially feasible without compromising perioperative and oncological outcomes. Future randomized trial with larger numbers will be required for further analysis in the Australian setting.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2021
Publisher: Springer Science and Business Media LLC
Date: 17-08-2020
DOI: 10.1186/S13073-020-00770-1
Abstract: DNA originating from degenerate tumour cells can be detected in the circulation in many tumour types, where it can be used as a marker of disease burden as well as to monitor treatment response. Although circulating tumour DNA (ctDNA) measurement has prognostic redictive value in metastatic prostate cancer, its utility in localised disease is unknown. We performed whole-genome sequencing of tumour-normal pairs in eight patients with clinically localised disease undergoing prostatectomy, identifying high confidence genomic aberrations. A bespoke DNA capture and lification panel against the highest prevalence, highest confidence aberrations for each in idual was designed and used to interrogate ctDNA isolated from plasma prospectively obtained pre- and post- (24 h and 6 weeks) surgery. In a separate cohort ( n = 189), we identified the presence of ctDNA TP53 mutations in preoperative plasma in a retrospective cohort and determined its association with biochemical- and metastasis-free survival. Tumour variants in ctDNA were positively identified pre-treatment in two of eight patients, which in both cases remained detectable postoperatively. Patients with tumour variants in ctDNA had extremely rapid disease recurrence and progression compared to those where variants could not be detected. In terms of aberrations targeted, single nucleotide and structural variants outperformed indels and copy number aberrations. Detection of ctDNA TP53 mutations was associated with a significantly shorter metastasis-free survival (6.2 vs. 9.5 years (HR 2.4 95% CIs 1.2–4.8, p = 0.014). CtDNA is uncommonly detected in localised prostate cancer, but its presence portends more rapidly progressive disease.
Publisher: Wiley
Date: 23-04-2019
DOI: 10.1111/BJU.14745
Abstract: To determine the prevalence of extended-spectrum β-lactamase (ESBL) in patients undergoing transrectal prostate biopsy, to assess the incidence of postoperative sepsis, to correlate the development of sepsis with the presence of preoperative ESBL on rectal swabs, and to assess the adequacy of prophylactic antibiotic guidelines in the context of local ESBL prevalence. Patients undergoing transrectal ultrasonography (TRUS)-guided biopsy at the Royal Melbourne Hospital between January 2012 and July 2016 had rectal swabs taken immediately prior to TRUS with specific cultures to identify the presence of ESBL. Patients were given a prophylactic antibiotic, 500 mg oral ciprofloxacin, 1 h before the TRUS procedure. Data were collected prospectively, with retrospective review of all readmitted patient files and audit data to ensure complete capture of events. A total of 387 TRUS-guided biopsy procedures were performed. Rectal swabs were correctly collected in 352 patients (91%). The median patient age was 65 years. In all, 25 (7%) ESBL-positive swabs were identified. Most ESBL were Escherichia coli. Half (50%) of ESBL were resistant to ciprofloxacin and all were sensitive to meropenem. A small increase in ESBL prevalence over time was not significant (R This study represents the largest Australian series to investigate ESBL prevalence, and reveals a rate lower than that of many other nations. Our sepsis rate is lower than many international series, perhaps because of our low ESBL rate and strict antibiotic prophylaxis. Preoperative swab results did not predict postoperative sepsis, and the process was therefore not useful for guiding antibiotic therapy. In this patient population, TRUS biopsy, with ciprofloxacin prophylaxis, remains a safe option for diagnostic prostate biopsy.
No related grants have been discovered for Ken Chow.