Surgery (Austin & Northern Health) - Theses

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    Health economic analysis and the role of multiparametric magnetic resonance imaging in prostate cancer
    Sathianathen, Niranjan ( 2023-08)
    Prostate cancer is the most common solid organ malignancy diagnosed in men. Its diagnosis has historically relied on clinical examination, prostate-specific antigen (PSA) screening and biopsy based on transrectal ultrasound. However, ultrasound is not sensitive in identifying abnormal, potentially cancerous areas in the prostate and therefore biopsy has been performed in a ‘random’ fashion that has led to missing clinically significant disease and over-diagnosing indolent disease. Developments in multiparametric magnetic resonance imaging (mpMRI) technology have suggested that it may be superior modality for local imaging of the prostate gland. This thesis will assess the role of mpMRI in the prostate cancer diagnostic pathway. The diagnostic accuracy of mpMRI was assessed to determine the sensitivity of abnormal mpMRI findings and the negative predictive value of a normal mpMRI. The latter is especially important in the proposal to use mpMRI as a tool to identify which men with an elevated PSA need to proceed to prostate biopsy. I will also assess which MRI findings in different populations of men should be recommended for biopsy. In addition, I will develop a nomogram to determine which men needed systematic sampling at the time of their prostate biopsy for accurate diagnosis of their disease and which men can be accurately diagnosed using targeted biopsy alone. Finally, I will perform an economic assessment to determine the cost-effectiveness of incorporating mpMRI in the primary biopsy setting and for men on active surveillance.
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    The role of zinc in prostate cancer
    Wetherell, David Robert ( 2018)
    Prostate cancer (PCa) is the most common cancer amongst Australian men. Zinc is an essential metal and is vital for normal function of the prostate gland. Castrate-resistant prostate cancer (CRPC) is becoming increasingly resistant and treatment options are limited in number and often associated with poor clinical outcomes. Therefore a pertinent clinical issue is to develop more effective treatment regimes. Zinc appears to play a role in PCa, but a true understanding leading to therapeutic developments is yet to be achieved. In particular evidence regarding cell proliferation and zinc uptake and levels in PCa cells is conflicting. HIF1α is a well-known prognostic marker in PCa associated with poor prognosis, resistance to treatment and development of metastatic disease, however the cause over-expression in CRPC remains a mystery. Therefore the ability of PCa cells to uptake and store zinc, and the role of zinc in PCa cell proliferation, tumour growth and HIF1α mediated survival was investigated in this thesis. CRPC-like human PC3 cells are significantly resistant to docetaxel chemotherapy and overexpress HIF1α protein, compared to normal prostate epithelial control cells (PNT1A). Cell proliferation assays (MTT) demonstrated that physiological zinc administered to PC3 cells significantly slowed growth compared to normal PNT1A and androgen-sensitive PCa (LNCaP) cells. The effect of zinc supplementation or zinc chelation (by TPEN) does not affect macroscopic growth in PC3 xenograft tumours. There is no significant difference in baseline total zinc concentration (measured by ICP-MS) between cell lines normal (PNT1A), androgen sensitive (LNCaP) and CRPC (DU145 and PC3) cells. However, CRPC-like PC3 cells contain significantly higher unbound free Zn2+ and Immunofluorescence Microscopy (IFM) subcellular distribution of Zn2+ in PC3 cells is unlike that seen in normal prostate epithelial cells. PC3 cells are resistant to oxidative stress injury. Zinc strongly induces HIF1α protein expression in these cells in a time and dose dependent manner. Zinc mediated oxidative protection in PC3 cells is a HIF1α dependent as demonstrated in a PC3 HIF1α-KD model. No such zinc protection was seen PNT1A cells. Zinc could be essential in the resistant nature of CRPC cells as Zn2+ ions rescue HIF1α protein expression and are implicated in the normoxic stabilisation of the HIF1α protein by competing with Fe2+ ions at the PHD binding sites. Therefore zinc dysregulation in CRPC cells is an important factor in the development of resistance, as well as potentially progression to metastatic disease and poor prognosis in PCa.
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    Characterisation of tumour-infiltrating lymphocytes in benign and malignant prostate tissues
    Woon, Teck Sing ( 2018)
    Over the past decade, we have seen a significant advancement in the treatment of metastatic castrate-resistant prostate cancer (PC). Cancer immunotherapy is now a reality, but the information on tumour infiltrating lymphocytes (TILs) in human prostate tissues is still limited. This project aims to evaluate and compare T cell characteristics in blood and tissues from patients with benign and malignant prostate conditions using flow-cytometry. Patients with benign prostatic hyperplasia (BPH) and normal prostate (NP) were used as controls and compared with patients with PC. We also examined the effects of androgen deprivation therapy (ADT) on systemic immune responses and immune regulation in patients with advanced/metastatic PC. The T cell characteristics evaluated were: (1) The proportion of regulatory T cell (Treg) and CD8/Treg ratio; (2) The percentage of activated cytotoxic lymphocytes (CTLs); and (3) The T cell maturation status. We found that the proportion of Treg in PC tissue was 5.6%, consistent with other studies. We did not find any differences in the proportion of Treg or CD8/Treg ratio in tissues for the three patient groups. When evaluating PC involved vs PC non-involved tissues, as an internal control comparison, PC involved tissues were found to have a higher percentage of Treg (6.89% vs 4.15%, p-value of 0.045) and a lower CD8+/Treg ratio (54 vs 119, p-value of 0.0032) than PC non-involved tissues. Despite a small number of 6 cases, the differences were statistically significant. These findings support the hypothesis of local immunosuppression in PC-involved tissues, and that such immunosuppression might be compartmentalised even to the level of specific lobes of the prostate. In this compartmentalised environment, PC cells can evade and survive the immune system’s defences. This study did not find any correlation between Gleason scores and the percentage of Treg in the CD4+ T cell subset or the CD8/Treg ratio either in PBMC or PC tissue. In the PC group, the same percentages of CD8+ T cells were found in both tissues and peripheral blood for majority of the patients. This showed that CD8+ T cells were not expelled or excluded from the tumour micro-environments, therefore the PC tissues were of the T-inflamed phenotype. When comparing tissue with PBMC, the levels of Treg are two times higher in tissues (both benign and malignant) than in peripheral blood. This could be a phenomenon across all tissue types and not exclusive to the prostate. Their role presumably is to maintain peripheral tolerance. We also found that the percentage of activated CD8+ T cells was ~20 times higher in tissues than in blood, regardless of the tissue type. Again, it is possible that this is not exclusive to the prostate. Profiling the immune infiltrates of other tissue types will help to clarify this. Using PCR, we have assessed the cytokine profiles in benign and malignant prostate tissues, and there were no significant differences in the levels of IFNγ, TNFα, TGFβ and IL-10 expressions. Our assays did not detect IL-4, IL-5 and IL-13 in any sample. To assess the impact of ADT on T cells, we evaluated the T cell characteristics in peripheral blood of 15 patients before ADT, at 3 months and then at 9-12 months after ADT. There was a significant reduction in the percentage of Treg by 15% after 3 months of ADT. This suggested there was an initial reduction in immune suppression during the first year of ADT. There was a significant decreased in the proportion of naïve T after 9-12 months of ADT. This suggested naïve T cells might have developed into other more mature T cell subsets after ADT.
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    Selection and management of men for active surveillance in low risk prostate cancer
    Wong, Lih-Ming ( 2016)
    Aims: To investigate: 1. Selection of men for active surveillance of prostate cancer a. Validation of risk calculators b. Suitability for inclusion of Gleason 3+4 disease. 2. Performance of prostate biopsy during AS a. Differences in quality of diagnostic biopsy between academic and referral centres. b. Optimization of biopsy templates c. Examination of prognostic indicators for disease progression Methods: Data were obtained from several difference sources: • Men suitable for AS on prostate biopsy but undergoing upfront radical prostatectomy were pooled from 3 international academic institutions in Cambridge (UK), Toronto (Canada) and Melbourne (Australia). • Prospectively maintained AS prostate cancer database at Princess Margaret Cancer Centre (PMCC) (1997-2012). Analyses performed: • Four risk calculators were assessed for their ability to predict different definitions of insignificant prostate cancer by area under the curve (AUC) of receiver operating characteristic curves and Brier scores for discrimination, calibration curves and decision curve analysis. • Men with biopsy Gleason 3+4 disease, suitable according to modified Royal Marsden, Sunnybrook Toronto and PRIAS selection criteria, were assessed for presence of adverse pathology at upfront radical prostatectomy. • Patients on AS at a tertiary referral centre (PMCC) were dichotomized depending on where their diagnostic biopsy was performed (interval versus external). Multivariate logistic regression was performed to examine for predictors of re-classification at the second, or confirmatory, biopsy. • Mapping of all patients with pathological progression at PMCC for location of disease progression enabled comparison of hypothetical biopsy templates (sextant and standard extended) to the institutional template used. • Men on AS at PMCC were evaluated for presence of disease progression at serial biopsy in the prostate transition zone (TZ). Multivariate Cox proportional hazards regression evaluated predictors of TZ progression. • At PMCC, men were dichotomized based on presence of cancer at their confirmatory biopsy. Pathological progression was investigated using a Cox proportional hazards regression model. Results: • All 4 models predicting presence of insignificant prostate cancer had weak discrimination at best (AUC 0.618-0.664). • Presence of Gleason 3+4 at biopsy, compared to 3+3 disease, increases risk of adverse pathology at radical prostatectomy if modified Sunnybrook Toronto criteria are used (19% versus 33%, p≤0.001). Using a stricter protocol such as PRIAS, there was no statistical difference between the groups. • External biopsy predicted both grade related re-classification (OR 4.14, C.I. 2.01-8.54, p<0.001) and volume related re-classification (OR 3.43, C.I. 1.87-6.25, p<0.001). • Sextant and standard extended biopsy templates were inferior to the institutional biopsy template in detecting presence of cancer (84% and 99% versus 100%), and pathological progression (47.9% and 81.9% versus 100%). • At each subsequent biopsy during AS, 2.7-6.7% of men had disease progression only in the TZ which would not have been detected if TZ biopsy was not performed. Predictors of TZ progression were maximum % single core (HR 1.99, C.I. 1.30-3.04, p=0.002), and MRI reporting cancer (HR 3.19, C.I. 1.23-8.27, p=0.02). • Men with no cancer at confirmatory biopsy were less likely to have pathological progression (HR 0.47, CI 0.29-0.77, p=0.003). Sub-analysis showed this was predictive of volume-related progression (HR=0.36, CI 0.20-0.62, p=0.0006) and not grade-related progression. Conclusions: • Utilization of models predicting suitability for AS should be used with caution as external validation in our cohort was weak. • If considering biopsy Gleason 3+4 disease for AS, a stricter protocol such as PRIAS must be utilized. • At PMCC, patients who had their initial diagnostic prostate biopsy for AS done externally, were more likely to have worse pathological features and re-classify on the second biopsy. • For men on AS, sextant and standard extended biopsy are less likely to detect prostate cancer or disease progression than the template used at PMCC. • TZ biopsy should be considered for all men having serial biopsy on AS, in particular those with high % core involvement or positive MRI findings. • Absence of cancer on B2 is associated with a significantly decreased risk of volume-related but not grade-related progression.
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    The role of hypoxia inducible factor 1 alpha (HIF1α) in prostate cancer
    Ranasinghe, Weranja Kalana Bodhisiri ( 2016)
    Prostate cancer (PC) is one of the most prevalent cancers in men. Although many PCs are indolent, a significant proportion will metastasize and develop resistance to therapy. Contemporary screening tests lack the finesse to accurately differentiate aggressive PCs from indolent tumours, potentially leading to over-diagnosis and over-treatment. While cellular hypoxia often plays an integral role in carcinogenesis and tumour progression, this connection has been difficult to demonstrate in PC. However, a downstream marker of hypoxia, Hypoxia inducible factor 1α (HIF1α), which is a transcription factor that protects cells against noxious stimuli, is frequently over expressed in PC. Therefore, the role of HIF1α in PC was investigated in this thesis. The Castrate resistant PC (CRPC)-like human PC cell lines PC3 and DU145 were found to over-express HIF1α protein compared to an androgen-sensitive cell line LNCaP under normoxic conditions. Using HIF1α 5’UTR-luciferase constructs in PC3 cells, further experiments revealed that increased translation of HIF1α mRNA regulated by a 70bp GC-rich, secondary structure in the 5’UTR of the HIF1α promoter may be responsible for normoxic HIF1α overexpression. Cell proliferation assays revealed that PC3 cells over-expressing HIF1α were more resistant to destruction by cytotoxic agents (H2O2 and 5-fluorouracil) than androgen-dependent LNCaP cells. Reduction of HIF1α expression in PC3 cells using RNA interference decreased both the resistance towards cytotoxic agents and cell migration. Conversely, in the androgen-dependent LNCaP cells overexpression of HIF1α increased the resistance to cytotoxic agents. One hundred prostate tumours were then immune-stained for HIF1α and outcomes measured. On multivariate analysis HIF1α was an independent risk factor for progression to metastatic PC (Hazard ratio (HR) 9.8, p = 0.017) and development of CRPC (HR 10.0, p = 0.021) in patients on androgen-deprivation therapy (ADT). Notably the tumours that did not express HIF1α did not metastasise or develop CRPC. Next, the effects of non-specific HIF1α inhibitors (digoxin, metformin and angiotensin-2 receptor blockers) were investigated in ninety-eight patients who had continuous ADT as first line therapy and developed CRPC. The median CRPC-free survival was longer in men using HIF1α inhibitors compared to those not on inhibitors (6.7 yrs vs. 2.7yrs, p=0.01) and there was a 71% reduction in the risk of developing CRPC (p=0.02) and an 81% reduction in the risk of developing metastases (p=0.02) after adjustment for Gleason score, age and PSA. Finally, the effects of metformin were investigated in 2055 men treated for PC with external beam radiotherapy. Surprisingly, metformin did not result in any improvement in time to biochemical failure, time to metastases or overall survival in men undergoing radiotherapy, but there was an 1.5 fold increase in PC-specific deaths (p<0.05) in men on metformin who received ADT when adjusted for cancer risk and co-morbidities. In conclusion, the results presented in this thesis indicate that HIF1α is a promising marker in PC, which may be used for early identification of cancers that potentially will progress to metastases and develop resistance to ADT. HIF1α is likely to contribute to metastasis and chemo-resistance of CRPC, targeted reduction of HIF1α may improve outcomes of aggressive PC.
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    Prognostic factors in urological malignancies
    SENGUPTA, SHOMIK ( 2014)
    BACKGROUND: The management of urologic cancers relies heavily on the implicit or explicit application of prognostic models. This may range from the appropriate selection of diagnostic tests based upon the pre-test probability of a positive finding, to an informed decision on choice of treatment modality or enrolment in suitable clinical trials. While some prognostic factors such as stage and grade are time-tested, others such as molecular and immunohistochemical markers or surgical approach are new and evolving. Furthermore, the literature abounds with nomograms, models, risk tables or groups which utilize varying combinations of predictor variables to prognosticate on myriad outcomes of interest. The aim of this body of work was to enhance our understanding of prognostication in urologic malignancies, particularly prostate cancer, renal cancer and urothelial cancer of the bladder, in various clinical settings. METHODS: Details of methodology vary – specifics are outlined in the relevant chapters. In general terms, an appropriate study population was defined based upon the hypothesis. Variables of interest were extracted from suitable database and / or clinical records, or assessed in the laboratory. Associations between predictors and outcomes were analysed using univariate and (where suitable) multivariate regression techniques. PRINCIPAL RESULTS: • PSA kinetics provide important prognostic information in various clinical settings, including prior to surgical treatment and after hormonal therapy • A persistently detectable PSA following radical prostatectomy is associated with a greater risk of progression and death, but with a long natural history • Younger patients with prostate cancer have less aggressive features, but a proportionately greater risk of progression and death despite curative surgical treatment • Obese patients with prostate cancer have more adverse pathologic features, but similar oncological outcomes compared to those of normal weight • A positive family history is associated with an increased risk of developing prostate cancer, but similar oncologic outcomes following surgical treatment • Gleason scoring has evolved over time, with consequent changes in the prognostic implications thereof • So-called “insignificant” prostate cancer has similar oncological outcomes to low-risk cancers overall, following surgical treatment • Patient suitability for brachytherapy as a single modality can be judged based on the clinically assessed risk of lymph node or seminal vesicle involvement • Clinical factors can predict the risk of nodal metastasis, thus allowing the rational selection of patients for pelvic lymphadenectomy at the time of radical prostatectomy • RALRP is associated with a lower rate of +SM compared to ORP, even after adjusting for known clinical and pathological risk factors • Renal cancers in solitary kidneys associated with vena caval extension may be treated by nephron-sparing surgery where technically suitable, although a high risk of disease progression and death remains • The pre-operative erythrocyte sedimentation rate provides independent prognostic information in patients with renal cancer • Renal lesions with low nephrometry score as measured using the R.E.N.A.L. have a greater likelihood of having benign or indolent histology • Histologic coagulative tumour necrosis within renal cancers is associated with poorer oncological outcomes after surgical treatment • Expression of the oncogene c-kit is rare within high-grade or sarcomatoid renal cancers • Muscle invasive urothelial cancers of the bladder are often infiltrated by profuse numbers of lymphocytes with a variety of phenotypes, although they appear not to impact on the risk of progression or death after surgical treatment • Peri-operative chemotherapy has been increasing in its use over recent years, and appears to reduce the risk of recurrence after surgical treatment of urothelial cancer of the bladder CONCLUSIONS: Many of the findings summarized above have had important implications for practice. For instance: • PSA kinetics are now in widespread use at various stages of prostate cancer management • Gleason scores from patients treated some time ago are often re-interpreted according to revised criteria
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    Identification of genetic changes in prostate tissue of men with prostate cancer from multiple breast cancer families
    Kavanagh, Liam ( 2013)
    Introduction: Male BRCA2 mutation carriers are at higher risk of developing aggressive prostate cancer. My research looks at DNA changes in prostate cancer specimens from men positive for a BRCA2 mutation. The first project involves DNA analysis of HG PIN tissue to look for loss of heterozygosity (LOH) in those carriers of a BRCA2 mutation. The purpose of looking for LOH in HG PIN of BRCA2 positive carriers is to ascertain if this tissue is a genomic predictor for tumorigenesis in this population. We also considered that whole exome copy-number analysis (CNA) of prostate cancer tissue, as well as HG PIN and normal prostate tissue from these BRCA2 men, may provide additional insight. Another inheritable mutation associated with prostate cancer is the HOXB13 mutation. We explored our cohort of prostate cancer men from breast cancer-rich families for the incidence of this mutation and impact on survival. We also investigated the incidence of the HOXB13 mutation in breast cancer women from breast cancer-rich families. Patients and Methods: Ten BRCA2 positive participants, from the kConFab cohort of high-risk breast cancer families, were identified , with access to archival prostate tissue specimens. Loss of heterozygosity (LOH) at the BRCA2 gene was examined using mutation specific PCR and sequencing of DNA from laser microdissected HG PIN. We also dispatched 15 DNA samples to Affymetrix for CNA: 9 prostate adenocarcinoma tissue DNA samples with 4 matched normal prostate tissue samples and 2 matched HG PIN samples. This data was analysed using specific software for microarray genetic analysis. For the HOXB13 study, the G84E variant was screened for using high resolution melting analysis in germ-line DNA in the index case or youngest affected member of 898 high-risk breast cancer families and in 1097 population controls. Results: Within this cohort of 10 pathogenic BRCA2 carriers, no patient displayed LOH at the mutation locus within HG PIN, irrespective of whether or not corresponding adenocarcinoma DNA displayed LOH. For the CNA project, our samples showed common sites of amplification at 8q, as well as deletions at 10q and 13q. Six out of 898 multi-case breast cancer families had carriers of the HOXB13 G84E variant: three families had either a single or multi-case family history of prostate cancer (3/99) and three had a personal and family history of breast cancer (3/799). Conclusion: Although HGPIN is considered a precursor to cancer, as no LOH was observed, this assay does not provide a genetic marker that may be considered a positive predictor of tumorigenesis in BRCA2 carriers. Regarding the CNA study, this is the first genomic analysis of this specific patient group, with our results have validated previous results of CNA in prostate cancer, as well as demonstrating the highly heterogenous nature of copy-number changes in this subset of patients. We confirm an association of the HOXB13 G84E variant with good prognosis prostate cancer in non BRCA1 or BRCA2 breast cancer families but we found no evidence for an increased risk of familial breast cancer.
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    Profiling tumour infiltrating lymphocytes in prostate cancer
    Rajarubendra, Nieroshan ( 2013)
    The purpose of this study was to understand the T cell processes that take place in prostate pathology. The subset of T cells and their functional and activational status was determined using flow cytometry and immunohistochemistry. Furthermore the use of androgen deprivation therapy (ADT) on the impact on T cells was also determined. The three main conditions of prostate pathology investigated were benign prostatic hyperplasia (BPH), chronic abacterial prostatitis (CAP) and prostate cancer (PCa). Patients with BPH were used as the control group. The results in CAP showed a trend of an active immune process, where there was an influx of CD4+ T lymphocytes cells (9.45%, p 0.1407) in prostate tissue and a reduction in T regulatory (Treg) cells (2.32%, p 0.0675) in the tissue and the blood (3.13%, p 0.0042). In PCa tissue there was an influx of both CD4+ T lymphocytes (9.63%, p 0.0296) and CD8+ lymphocytes (12.81%, p 0.0063). Correspondingly a trend was seen with an increase in Treg cells in prostate tissue (2.12%, p 0.2480). This resulted in the ratios between CD4:CD8, CD4:Treg and CD8:Treg in PCa to be similar to BPH indicating a net homeostasis in immune action. The use of Treg cells as a prognostic indicator was compared to current pathological markers, where a higher number of Treg cells was seen in patients with extraprostatic spread (3.52%, p 0.0371), seminal vesicle extension (10.74%, p 0.0249), PSA relapse (4.39%, p 0.0162) and higher Gleason score (3.89%, p 0.0376). Despite showing a homeostatic picture in PCa, the functional status of CD8+ T lymphocytes was assessed. There were lower proportions of naïve T cells (9.86%, p 0.0068) and central memory T cells (8.60%, p 0.0258) in PCa tissue. While there was an increase in terminal effector T cells (12.06%, p 0.0019) and effector memory T cells (8.63%, p 0.0253). This implied that the tumour cells had been recognized and a shift in the dynamics towards a local cytotoxic environment. These cytotoxic T lymphocytes were activated as demonstrated by increased expression of CD69 (13.35%, p 0.0083). Despite showing activation, the effectiveness of these cells in the implementation of an anti-tumour response was assessed by evaluating the distribution of cytokines IFNγ, TGFβ and IL-10. However no clear pattern was seen, but it will require further investigation with a larger sample population. The use of ADT has been shown to reverse thymic involution and restore peripheral T cell population. However from this study there was no difference seen in the subset numbers, functional and activational status of T lymphocytes. From this study, the profile of prostatic pathology is better understood. The T cell profile especially in the in the local tumour environment of PCa shows a dynamic process between cytotoxic and immunosuppressive cells. This will allow for the development of further studies to understand the immune interaction with PCa.