Sir Peter MacCallum Department of Oncology - Theses
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ItemThe role of nature in cancer patients' experiences of health and recovery( 2017)This thesis explores the role of nature in cancer patients’ experiences of health and recovery. Using a 2-Phase mixed-method approach, the investigation aimed to generate new theoretical understanding about cancer patients’ use of nature and how they find nature engagement helpful or not when confronting cancer diagnosis. The project’s translational focus was to produce expert recommendations for nature-based care opportunities in oncology contexts based on patient-reported data. First, a systematic literature review and meta-synthesis was conducted to describe the existing qualitative research evidence base relating to nature experiences and nature-based interventions for cancer populations specifically. The aim was to describe current knowledge about the role of nature in cancer patients’ lives. From eleven eligible publications, seven inter-related core themes were identified as follows: connecting with what is valued; being elsewhere, seeing and feeling differently; exploration, inner and outer excursions; home and safe; symbolism, understanding and communicating differently; benefitting from old and new physical activities; and, enriching aesthetic experiences. Next, an in-depth investigation of cancer patients’ own experiences with nature used primary data to develop a new Grounded Theory describing the underlying and intrapsychic mechanisms of cancer patients’ phenomenal nature experiences. Based on qualitative data collected from semi-structured interviews with 20 cancer patients (9 female), the resulting theory model explores the unique role nature plays when diagnosed with cancer. It constitutes a core category and two inter-related themes, which explain a normalization process in which patients moved towards a state of 'new-normal' (Core Category). Nature functioned in this process as a support structure that repositioned patients and nurtured their inner and outer capacities to respond and connect more effectively (Theme A). Once enabled and comforted, participants could engage survival and reconstructive manoeuvres and explore the consequences of cancer in their present lives and possible futures (Theme B). A dynamic relationship was shown between moving away while, simultaneously, advancing towards the cancer reality in order for patients to incorporate their cancer experiences into a shifting normality. From a place of comfort and safety, patients felt supported to deal differently and more creatively with the threat and demands of cancer diagnosis, treatment, and outlook. The descriptively rich interview data provided further insights into patients’ own recommendations for nature engagement in the oncology context, which were extracted from the transcriptions using deductive content analysis and were consolidated into patient recommendations for nature-based care opportunities. These incorporated using nature for vital sensory stimulation and engagement, using nature for personal space and freedom to enable private and social exploration, using views of nature for distraction and comfort, and accessing nature for physical activity and movement. Three critical factors were determined to avoid adverse experiences: determining appropriate health-care expenditure and resourcing on nature-based interventions, selection of appropriate nature-based design materials, and exercising caution around demanding nature engagement and harsh weather conditions. A questionnaire survey study was conducted following an environmental intervention in an oncology waiting room to assess patient, visitor, and staff responses to design changes, which included the addition of artificial plant materials. Based on 143 returned survey questionnaires consisting of 73 cancer patients, 13 staff, 52 carers, and five ‘other’, it was found that the environmental intervention positively impacted patients, staff, and carers’ perceptions of the oncology waiting room environment. Patients, staff, and carers mostly accepted artificial plants as an alternative design solution to real plants. Comments included positive appraisals and occasional adverse reactions to artificial plants. No significant differences were found between patient, staff, and carer reactions. Insights gleaned from the initial, exploratory phase formed the basis for a second phase investigation comprising an international online Delphi study. The aim was to solicit knowledge from relevant experts drawn from a range of healthcare practitioners, management, designers, and researchers to determine feasible opportunities for, and barriers to, providing helpful nature engagement in oncology settings. Two hundred potential panellists were identified and sent an invitation to participate. Thirty-eight experts were recruited who represented 7 countries: Australia (19), USA (8), UK (3), New Zealand (2), Canada (2), Denmark (3), and Sweden (1). This study followed a structured, iterative feedback process that queried and synthesized expert opinion. Cancer patients’ own recommendations, extracted from phase 1, were used as a starting point for the Delphi panel to brainstorm and develop their own ideas about appropriate nature-based opportunities in oncology settings and the barriers to their provision. In total, 250 separate suggestions for opportunities and 205 suggestions for barriers were collected. Further analysis condensed these into 55 unique items (35 opportunities, 20 barriers). The Delphi panel’s list of recommendations included “Window views from clinical areas onto nature […]” as the highest rated opportunity, and “Building design and site constraints […]” as the highest rated barrier to providing nature-based supports for oncology care. Finally, a synthesis of findings from the overall investigation, which constitutes six publications, is provided to summarize and outline the salient findings and discern the study’s limitations in order to suggest pathways for future research. This synthesis produced a conceptual framework consolidating new theoretical understanding and empirical content from patient and expert-reported data about nature-based care opportunities in the oncology setting. The thesis findings provide evidence for multiple uses of nature as a supportive aid in the cancer care context. Concrete recommendations have resulted to guide the application of nature based concepts in future oncology setting design and may be considered when developing additional supportive care services. The findings may assist healthcare practitioners, designers, researchers, and patients themselves to creatively and practically participate in future oncology care practice and design.
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ItemIdentification of cooperating oncogenic lesions in Myc-driven lymphoma( 2017)MYC is a potent oncogene that is deregulated in nearly 50% of all human malignancies and as such, is considered an attractive molecular target for inhibition. However, MYC is rarely mutated, has no enzymatic activity that can be pharmacologically exploited and is expressed by normal cells leading to the current view that MYC is “undruggable” and indeed, its pharmacological inhibition has proved elusive. Therefore, discovering genes and pathways that interact with oncogenic MYC signalling and identifying them as potential therapeutic targets in cancers with ectopic MYC expression is of high clinical importance. The Eμ-Myc mouse has been utilised extensively as a faithful model of MYC-driven B cell lymphomagenesis. The Eμ-Myc transgene mimics the t(8;14) translocation apparent in Burkitt’s lymphoma, where ectopic Myc expression is driven by the Eμ- (IGH) promoter elements. Despite being driven by a single oncogene, Eμ-Myc lymphomas demonstrate remarkable heterogeneity indicating that the pathway to frank clonal neoplasia relies on oncogenic Myc signalling and the acquisition of at least one other mutation that cooperates with Myc. Hence, the Eμ-Myc model is a powerful tool in identifying MYC-cooperative genes and pathways. However, to date there has only been partial characterisation of the secondary, tertiary and quaternary mutations that can cooperate with Myc in driving Eμ-Myc lymphomagenesis. To identify somatically acquired Myc-cooperative lesions, massive-parallel sequencing was applied to spontaneous Eμ-Myc B cell lymphomas. Whole genome sequencing was used to map three copies of the Eμ-Myc transgene to chromosome 19 in the germline corresponding with an adjacent chromosome 19 segmental copy number gain. The chromosome 19 amplicon is in a region syntenic to an oncogenic region frequently amplified in human B cell malignancies. The chromosome 19 amplicon was demonstrated to undergo additional somatic gain in 50% of Eμ-Myc lymphoma. In addition to the identification of mutations in genes already implicated in Eμ-Myc lymphoma (Trp53, Cdkn2a, Nras, Kras), whole exome sequencing identified high frequency protein truncating mutations in Bcl6-co-repressor (Bcor). Furthermore, co-occurring tertiary driver lesions involving Cdkn2a (p19ARF) deletion and either Bcor or Ras mutations were identified in clonal Eμ-Myc lymphomas. RNAi and CRISPR-Cas9 mediated knockdown/knockout of Bcor in Eμ-Myc foetal liver hematopoietic stem cells reconstituted into recipient mice demonstrated significantly reduced latency of disease onset, validating Bcor as a tumor suppressor gene in the Eμ-Myc model. Gene-expression profiling of these Eμ-Myc tumours with forced Bcor-loss identified a reliable signature of Bcor loss that was distinct to Trp53 mutation signatures and was redolent of Tgfβ-pathway activation signature. The Eμ-Myc model of lymphoma has been heavily utilised but never fully genomically characterised until now. By applying next generation sequencing technology to a first generation animal model of cancer, this thesis challenges several persisting assumptions made about Eμ-Myc lymphoma. Firstly, data herein suggests that both oncogenic Myc expression along with the chromosome 19 amplification is the initiating driver event in Eμ-Myc lymphoma. This has obvious implications for the conclusions drawn in many publications predicated on the assumption that ectopic Myc expression is the exclusive initiating oncogenic lesion in Eμ-Myc lymphoma. Secondly, the discovery that homozygous deletion of Cdkn2a does not totally attenuate selective pressure for the acquisition of tertiary driver mutations indicates the significance of Cdkn2a deletion in Eμ-Myc lymphoma is overestimated. Thus, deductions made about the cooperative mechanism between CDKN2A and how it opposes proliferative MYC-signalling in human neoplastic transformation may need to be revisited. Finally, the identification of biologically functional high frequency Bcor mutations in Eμ-Myc lymphoma has defined a novel pathway that is potentially capable of restraining oncogenic MYC activity. That Bcor inactivation is reminiscent of Tgfβ-pathway enhancement is suggestive of perturbation of the oncogene induced senescence pathway. If this is the pathway through which Bcor exerts its tumour suppressive activity then it is feasible that dissection of this pathway will lead to the identification of novel therapeutic targets that can be selectively exploited in human malignancies in which MYC is oncogenically deregulated.