The reported median survival time for patients who are diagnosed with high grade astrocytomas and who undergo postoperative radiotherapy is of the order of 24 to 40 weeks. The course of radiotherapy administered to these patients takes up a considerable portion of their expected survival time. Therefore, any means of reducing the treatment time may contribute to an enhanced quality of life for these patients. A potentially useful method for the reduction of the treatment time may be achieved with the use of continuous low dose rate external beam radiotherapy, where the treatment is administered over a 12 to 24 hour period. A relationship between fractionated and continuous low dose rate irradiation has been reported for skin, however, no such relationship has been reported for the brain. Low dose rate protocols that are equivalent in effect to fractionated (conventional) protocols can be derived using the linear quadratic theory, provided that quantitative radiobiological data for normal tissue (brain) is known. Thus, the aim of the current study is to test the radiation tolerance of the rat brain to low dose rate and fractionated radiation in order to establish the values for the parameters of the linear quadratic model.

Background: Due to the poor outcomes achieved in acute myeloid leukaemia (AML) treatment, the Red Cross War Memorial Children's Hospital (RCWMCH) Oncology service changed from a BFM-87 based protocol to one based on MRC-AML15 in 2007. Rationale: This study was designed to assess the outcomes and treatment - related toxicity among children treated with RCWMCH protocol Rx 2071. Methods: This was a retrospective review of AML patients treated with Rx2071 between 2007 and 2012 at RCWMCH. Patients with acute promyelocytic leukaemia (APL) and Down Syndrome were excluded. Risk was assigned by cytogenetics. Good risk patients were those with t(8;21), t(16,16) and inv(16). Poor and standard risk included all other cytogenetics according to MRC-AML15. Data pertaining to toxicity was obtained from patient folders. Results: Thirty five children were treated on Rx 2071 during the study period. Males comprised 51.4% (18/35) and females 48.6% (17/35). Age at diagnosis ranged from 0.33 to 12.51 years with the median being 5.68 years. Follow-up from remission in the patients who survived ranged from 1 year 10 months to 9 years 1 month with a median of 62.5 months. Fifteen patients had favourable cytogenetics. Event free survival (EFS) for the good risk group was 85.6%. Twenty patients presented with standard/poor risk cytogenetics. Five patients were deemed poor risk with one having major karyotype abnormalities and four not achieving remission. The remaining fifteen were deemed standard risk by cytogenetics. EFS in this group was 32.4%. Two standard/poor risk patients were transplanted in first complete remission (CR1) and two patients were transplanted in second complete remission. (CR2) Patients had a median of four neutropaenic fevers, and required a median of eight packed cell and eleven platelet transfusions. There were 39 positive blood cultures. There were no chemotherapy related deaths. Discussion: The EFS for good risk patients is excellent but the EFS for standard/poor risk group is not on par with results being achieved in high income countries. The toxicity is not excessive on Rx2071. The results achieved on this protocol were superior to that of the previous BFM- based protocol. Conclusion: The results of this study support the continued use of Rx2071 at RCWMCH.

Background: The majority of central nervous system tumours in children are low grade gliomas (LGG). Long-term survival rates are high with a slow, progressive course. Tumour location and extent of resection affect outcome. Adjuvant therapy has an important role. Rationale: This study evaluated the demographic data of our patient population, the characteristics of LGGs in our setting, the time to presentation, and the role of adjuvant therapy including more targeted, novel biologic therapy such as BRAF/MEK inhibitors. The outcome of children with LGGs in our institution was assessed. Methods: A retrospective analysis was performed on all children < 15 years of age diagnosed with a LGG at Red Cross War Memorial Children's Hospital (RCWMCH) between 2001 and 2017. Data were collected from patient hospital folders, as well as paediatric oncology records and Groote Schuur Hospital radiotherapy records. Results: Eighty-six children aged 0.10-13.76 years (median 4.74 years) were diagnosed with LGGs between 2001 and 2017 at RCWMCH. Median time to presentation was 60 days. Sixtyfive patients (76%) were classified as having a WHO Grade I and 21 patients WHO Grade II (24%) tumours. Five patients (6%) had metastatic disease at presentation. The most common sites involved were the cerebellum (27%), hypothalamus (17%) and cerebrum (14%). The most common histology was juvenile pilocytic astrocytoma (JPA) (n=62; 73%). Gross total resection (GTR) was achieved in 21 patients (24%). Twenty-four patients (27%) received chemotherapy of which 11 patients progressed. Twenty-two patients received radiotherapy (26%), of which 3 patients progressed. The estimated 5-year overall survival (OS) was 86.8% and the estimated 5-year progression free survival (PFS) was 42.8%. The presence of a BRAFV600E mutation was checked in 4 patients since 2013, all had JPA histology, and all were negative. Discussion: Our patient demographic differed from published data with respect to younger age at presentation and female predominance. Time to presentation was relatively short. The majority of LGGs were cerebellar, with JPA histology being the most common. GTR was achieved in almost a quarter of patients. WHO Grade II histology did not significantly impact PFS and OS. Children < 3 years had a lower PFS compared to children > 3 years, but OS was similar. OS in this study was comparable to published data in developed countries, however PFS was slightly lower. Conclusion: Our outcomes are similar to those achieved in developed countries. Chemotherapy and radiotherapy are valuable adjuncts to treatment. The presence of a BRAF alterations should be tested in recurrent/progressive disease, to guide use of novel treatments.

abstract: Necroptosis is a pro-inflammatory mechanism of programmed cell death. It has been implicated in many diseases such as inflammatory diseases, neurodegenerative diseases, cancer and during viral infections. The focus of this research work was to establish the relationship between poxvirus pathogenesis and necroptosis, and the translation implications of necroptosis in oncolytic virotherapy. Vaccinia virus (VACV) is the currently used vaccine for smallpox and it has also been developed as a vaccine vector for several pathogens. E3L is one of the key innate immune evasion genes of VACV and it encodes E3 protein composed of dsRNA binding domain in the C-terminus and Z-NA-binding domain (Z-NA BD) in the N terminus. Both domains are necessary for type 1 interferon resistance and pathogenesis. Recently, it has been shown that in in vitro, the N-terminus of E3 is necessary to inhibit necroptosis occurring through the host-encoded cellular proteins RIP3 and Z-NA-binding protein DAI interaction leading to phosphorylation of MLKL, the key executioner step in the pathway. The research work presented here clearly demonstrates that in a mouse model, the N-terminus of VACV E3 is necessary to inhibit necroptosis during pathogenesis in mice. Another poxvirus belonging to the same family as VACV is monkeypox virus (MPXV) and is an emerging human pathogen. MPXV contains a natural truncation in the N-terminus of its E3 homologue, F3. The results indicate that during MPXV infection in mice, pathogenesis was higher only in DAI knockout mice and not in MLKL knockout mice, suggesting that DAI is possibly activating other proteins not leading to necroptosis. The characterization of VACV as an oncolytic virus was carried out with a focus on future clinical trials. In this study, a pan screening was conducted in various cancer cell lines as many cancers downregulate necroptotic proteins. The results reveal that the N-terminal deletion mutant of VACV selectively replicates in cancer cell lines with a deficient necroptotic pathway and thus, can be used as a potential treatment against specific tumors and evidently, provides abundant scope for future studies. / Dissertation/Thesis / Doctoral Dissertation Neuroscience 2020

Background Accurate delivery of radiotherapy is a paramount component of providing safe oncological care. Margins are applied when planning radiotherapy to account for subclinical tumour spread, physiological movement and set-up error. Set-up error is unique to each radiotherapy institution and should be calculated for each organ site to ensure safe delivery of treatment. Aim and setting The aim of this study is to calculate the random and systematic set-up error for a cohort of patients with intracranial tumours treated with 3D Conformal Radiotherapy at the Department of Radiation Oncology, Groote Schuur Hospital, South Africa. After obtaining above mentioned data the ideal CTV-PTV expansion margin was calculated using published CTV-PTV expansion margin recipes. Patients and methods The Electronic Portal Images (EPID) of 20 patients who met the inclusion criteria were compared to their Digitally Reconstructed Radiograph (DRR). The set-up error for each patient was measured after which the random (s) and systematic (S) set-up error for the study group could be calculated. With both these values known the CTV-PTV expansion margin could be determined. Results The largest error was in the Superior/Inferior (SI) direction, followed by the Medial/Lateral (ML) direction and least in the Anterior/Posterior (AP) direction with 87.7%, 76.2% and 91.6% of the errors in the ML, SI and AP directions respectively being less than 3mm. There was no error larger than 5mm in the ML or AP direction with 6.1% of the SI error larger than 5mm. The random and systematic error in all three directions for this patient cohort were less than 2mm conforming to acceptable standards of delivering safe radiotherapy. Using Stroom's margin recipe (2S + 0.7s) a CTV-PTV expansion margin of 5mm can safely be applied for this patient cohort. Conclusion When treating patients with intracranial tumours at Groote Schuur Hospital the CTV-PTV expansion margin can safely be reduced from 1cm to 5mm.

It is generally accepted that energy is required for repair of radiation-induced damage in living cells. Some of this energy is probably provided by adenosine triphosphate (ATP), which is derived from energy substrates via energy metabolism. This dissertation follows two general avenues. The first explores the effect of radiation on ATP levels after irradiation of cells. The second investigates the effect of inhibitors of certain pathways associated with energy metabolism on radiation response. It was proposed that ATP levels might be raised after irradiation in some systems and that this rise in ATP might be due to compensatory mechanisms related to repair. Experiments were conducted using B16 melanoma cells in vitro and using normal murine liver and CaNT tumours in vivo. ATP concentration was measured in extracts of these cells after irradiation using the luciferase-luciferin method. No major changes from unirradiated controls were found. Several types of substrates exist from which cells can derive energy, including glucose and glutamine which are initially metabolised via glycolysis and glutaminolysis, respectively, before their products are further metabolised in respiration. Since energy is necessary for repair of radiation damage, it has been proposed that the inhibition of energy metabolism might alter the radiation response of cells. An inhibitor of glycolysis, 2-deoxyglucose (2DG), and an inhibitor of glutaminolysis, aminooxyacetic acid (AOA), were administered to CHO cells in vitro to determine the effects of these substances on cellular radiosensitivity and repair. Repair was assessed by means of a split radiation dose experiment. The design of such an experiment required that cells be exposed to inhibitory test media for different times between two fractions of radiation. Any changes in clonogenic survival with time between tween fractions could, therefore be as a result of repair effects or as a result of changes in radiosensitivity. A method of estimating and subtracting the effects of radiosensitivity to make conclusions concerning repair is presented and discussed. Most combinations of 2DG, AOA, glucose omission and glutamine omission in culture media resulted in reductions in repair rate but the extent of repair was found to vary from one medium variation to the next. In addition, the effects of various culture media on glycolysis/PPP (glycolysis/pentose phosphate pathway) and glutaminolysis were investigated by determining the production of CO2 and lactate from radiolabelled-glucose and -glutamine substrates. It was apparent that the presence of either of the inhibitors, 2DG or AOA, could inhibit the activity of glutaminolysis and reduce oxygen consumption. 2DG was shown to inhibit glycolysis/PPP but AOA was shown to stimulate glycolysis/PPP, suggesting a regulatory link between glutaminolysis and glycolysis/PPP. The presence of either inhibitor resulted in a reduction in the rate of radiation damage repair. The medium which had the most significant effect in respect of repair inhibition and increased radiosensitivity was medium lacking both glucose and glutamine and containing both 2DG and AOA. This medium was shown to inhibit oxygen consumption and to result in a depression of both cellular glycolysis/PPP and glutaminolysis. The effect of 2DG on the rate of growth and radiation induced growth delay of three murine tumours in vivo was assessed. 2DG alone inhibited the growth of B16 tumours. However, 2DG alone produced little if any change in the rates of growth of Fib/T tumours and rhabdomyosarcomas but the combination of 2DG and AOA produced an inhibition of growth in the Fib/T tumour. 2DG appeared to enhance the effects of radiation in the Fib/T and B16 tumours but not in the rhabdomyosarcoma, although, in the Fib/T, the combination of AOA, 2DG and radiation was less effective in inhibiting tumour growth than was radiation alone. The effects of radiation and 2DG did not appear to be additive in the Fib/T tumour and the B16 tumours which may imply an influence of 2DG on repair or radiosensitivity. This work suggests that the effects of radiation can be altered by manipulation of metabolic pathways associated with the supply of energy. However, a complex interaction of pathways is probably also involved and it is the detail of this interaction which may partially determine the severity of radiation response.

Background: Febrile neutropenia (FN) is the commonest fatal acute complication of cancer treatment in children. The need for regional clinical decision rules allowing for home-based care in those at low risk for adverse outcomes has been identified. Aims: To evaluate the prevalence and potential risk factors for FN, identify adverse outcomes and validate a tool to identify risk for adverse outcomes in a cohort of children treated for cancer at the Red Cross War Memorial Children's Hospital, Cape-Town, South Africa. Methodology: A retrospective cohort study from 1st January 2017 to 31st December 2019. Results: In all, 179 patients had chemotherapy and 267 FN episodes occurred. Independent predictors of FN were AML (p = 0.039), ALL (p = 0.020) and intensive chemotherapy (p = < 0.001). Mucositis (p = 0.001), CVAD (p = 0.004, haematologic malignancies (p = 0.040), blood transfusion during FN episode (p = 0.001) and severe neutropenia (white cell counts< 0.3 x 109 cells/L) (p = < 0.001) were risk factors for adverse outcomes. The mortality rate from FN was 3.57%. Independent predictors of adverse outcomes were AML (p = 0.001), CVAD in-situ (p = 0.019) and severe neutropenia (p = 0.005). Validation of risk stratification for adverse outcomes using the Swiss Paediatric Oncology Group (SPOG) index with a cut-off value of nine demonstrated a sensitivity and specificity of 52.3% and 62.0%, respectively. Positive and negative predictive values were 56.3% and 58.2%, respectively, with an overall accuracy of 57.4%. In our cohort, coordinates of the curve are best able to predict adverse outcomes with a cut-off value of 7.5. Conclusion: Adverse outcomes from treatment are likely in children with AML, severe neutropenia and those with CVADs in-situ. A lower cut-off of 7.5 using the SPOG FN risk index best predicted adverse outcomes in our cohort.

OBJECTIVES: To retrospectively review the patient demographics, disease profile and treatment outcomes of paediatric patients treated for ependymoma at our institution. STUDY DESIGN AND METHODS: 51 eligible patients were treated between 1980 and 2013. The median age at presentation was 6 years. The majority of patients were male (66,7%), had infratentorial tumours (62,7%) and had low-grade tumours (70,6%). Gross total resection (GTR) was achieved in 22 patients (43,1%). Thirtyeight patients received adjuvant radiotherapy (76,5%) and 10 (19,6%) received adjuvant chemotherapy. RESULTS: The 5-year overall survival (OS) was 63,3 % (median follow up of 46 months). The 5 year progression free survival (PFS) was 50,70%. Seventeen (33,3%) patients experienced treatment failure, of which 13 (76,5%) represented local failure. The median time to first relapse was 20 months. The 5 year PFS for children > 3 was 50,0 % and 27,7% for children ≤ 3 years of age (p = 0.0356). GTR had a superior 5- year OS of 73,9% over subtotal resection with a value of 56,7% (p = 0.0016). Similarly an improved 5-year PFS of 70,3% versus 29,1% was observed with GTR over subtotal resection (p = <0.0001). Patients who received adjuvant radiotherapy (RT) had significantly better outcomes than those in whom RT was not given (p = <0.0001, 5 year OS of 69,7% versus 37,5%). CONCLUSION: This review confirms the finding that GTR is associated with improved outcomes and that adjuvant radiation therapy positively impacts survival. The worse outcomes in the younger age group requires further evaluation and possible change in treatment protocol for this group of patients.

Background : Cervical cancer is the second commonest gynaecological cancer amongst women worldwide and the leading cause of cancer deaths in developing countries – contributing 83% of new cases and 85% of all deaths annually to the burden of this disease. Information and awareness of this illness in the developing world is still inferior, and mortality is increasing. In the developing world, late presentation, advanced-stage disease and a poorly run screening programme (covering only 55% of the South African population) are all contributing factors to this statistic. Approximately 20% of all South African women in their reproductive age are also HIV positive. With the rising burden of cervical cancer and the emergence of HIV as an influencing comorbidity, South Africa adopted a national cervical screening programme, rolled out in 2000 as well as an HCT (HIV counselling and testing) programme formalised in 2011. With these initiatives now in place, this study examined trends and compared 5-year survival outcomes between two decades for cervical cancer among young women. Methods : The study undertook a retrospective audit of files and information on the pre-existing cervical cancer database, and appropriate data was extracted (HREC REF 344/2011). Survival and disease outcomes at five years, as well as time to recurrence, was assessed, together with other demographics of the study population. Patients included in the study were non-pregnant female patients, aged 40 years and younger at the time of registration with the Groote Schuur Hospital (GSH) Oncology Unit (LE 33). The diagnosis of cervical cancer had to have been confirmed histologically, as either squamous cell carcinoma or adenosquamous carcinoma or adenocarcinoma. Patients must have attended at the LE 33 unit on or from 1 January 1993 until and including 31 December 2012. The two decades were studied and 5-year outcomes from each decade were analysed and reviewed using Kaplan-Meier curves and univariate analyses. The study compared data using Log Rank tests and p-values. Findings : The two decade-groups under study showed no difference in trends of survival regarding age, treatment type and histology. Albeit small numbers, adenocarcinoma was the histology that had the best probability of survival during both decades. There were more patients with early-stage cancer (stage 1 and 2) diagnosed in decade B (2003 – 2012) than A (1993 – 2002). Within this early-stage cervical cancer cohort, there is a trend toward more locally-advanced (stage 2) cancer in the more recent decade. The proportion of patients presenting with stage 1a and 1b cancer with tumours 4 cm and less has halved from decade A to decade B. The proportion of stage 2 cancers presenting with tumours 2 – 4cm in size during decade B has risen almost 3-fold to that of decade A. This suggests a developing trend of presentation of more locally-advanced cancer. During both decades, stage 1 cervical cancers had the best probability of survival, with an improvement in mean survival from decade A (average of 44 months) to decade B (average of 58 months). The trend of stage 2 disease has deteriorated, with a decrease in mean survival (from 48 months in decade A to 21 months in decade B), an increase in cancer-related deaths and a shorter time to relapse. The number of patients presenting with late-stage disease (stages 3 and 4) has declined. HIV positive status played an influential role in tumour size on presentation and probability of 5-year disease-free survival. Young women who were HIV positive also fared less favourably when compared to NP (not positive) women in terms of mean survival. Due to the small sample size and that the majority of patients in decade A were untested, further HIV comparisons were not credible. Interpretation : The study suggests a moving trend towards young patients that are being diagnosed with the more locally-advanced early-stage disease in the more recent decade than ten years prior. HIV status seemingly played an influential comorbid role in patients diagnosed with cervical cancer. Patients with the locallyadvanced disease appear to have worse outcomes in the latter decade. In an attempt to curb this potentially curable disease in this subset of young women, a greater focus on earlier screening interventions, prompt diagnosis and appropriate and timeous treatment of cervical cancer, together with optimisation of comorbidities like HIV are needed.

Includes abstract. Includes bibliographical references.