Browsing by Author "Punt, Lydia"

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    Open Access
    Evaluation of target motion and determination optional treatment margins for prostate cancer treated with external beam radiotherapy on Halcyon
    (2023) Algar, Marion; Punt, Lydia
    Background External beam radiotherapy (EBRT) is an important part of the treatment for prostate cancer. To account for organ motion and set-up error, margins are used in radiotherapy planning. These are essential for the delivery of safe and effective treatment. Aim and Setting To measure prostate motion during the course of EBRT on the HalcyonTM at Groote Schuur Hospital. Using published margin recipes, the minimum clinical target volume (CTV)-planning target volume (PTV) expansion margin was calculated. Patients and Methods Prostate motion was evaluated by comparing prostate position on the planning CT to cone-beam CT (CBCT) scans. Prostate position error in the medio-lateral (ML), antero-posterior (AP) and superoinferior (SI) directions was measured for each CBCT. The systematic (Σ) and random (σ) error of prostate motion was calculated. The minimum CTV-PTV margin was determined. Results The mean position error of the prostate was -0.04mm (95% CI -0.14, 0.10), -0.30mm (95% CI -0.70, 0.15) and -0.40mm (95% CI -0.89, 0.00) in the ML, AP and SI directions, respectively. Using Van Herk's margin formula (2.5Σ +0.7σ), the following minimum CTV-PTV margins for the ML, AP and SI directions were calculated: 1.9mm, 6.9mm and 7.8mm, respectively. Using Stroom's margin formula (2Σ +0.7σ), the following minimum CTV-PTV margins for the ML, AP and SI directions were calculated: 1.6mm, 5.8mm and 6.6mm, respectively. Conclusion Based on prostate motion, our institution's current margins are sufficient. However, further studies are necessary to measure other factors that influence the CTV-PTV margin before considering reducing this margin.
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    Open Access
    Treatment outcomes of Her-2 positive Breast Cancer in the absence of Her-2 targeting agents at Groote Schuur Hospital, Cape Town, South Africa. Are we doing enough?
    (2024) Sirkhotte, Aqeela; Punt, Lydia; Hunter Alistair
    Purpose: Breast Cancer has an estimated 2.3 billion cases globally. It is the second most common cause of cancer-related mortality in Sub-Saharan Africa. The addition of anti- Her-2 targeted therapy (Trastuzumab) to either adjuvant or neo-adjuvant treatment significantly improves disease-free survival and overall survival of women with early-stage Her-2 positive breast cancer. However, at Groote Schuur Hospital anti-Her-2 targeted treatment is not available. We have therefore evaluated to what extent our patients may be disadvantaged. The primary aims of this study were to evaluate the 3 and 5-year overall survival (OS) and recurrence free survival (RFS) of patients treated for Her-2 positive breast cancer at Groote Schuur Hospital. Secondary outcomes were to compare the OS and RFS of patients with hormone- receptor positive (HR+) and hormone-receptor negative (HR-) Her-2 positive (Her-2+) breast cancer. Methods: A retrospective folder review was conducted of all patients treated for Her-2 positive breast cancer between January 2016 and December 2016 at the breast oncology clinic at Groote Schuur Hospital, Cape Town. All patients with histologically proven Her-2 2+ and 3+ breast cancer stage I to III between 25 and 70 years old were included. Of the 561 patients on the hospital's electronic patient registry (EPR), 112 fulfilled the inclusion criteria and of these 87 patients were included for formal analysis due to missing folders. OS and RFS were calculated using Kaplan Meier analysis. A multivariate analysis using the Cox regression model and log rank testing was used to determine any association between OS or RFS and age, hormone receptors, or clinical stage. A p-value of <0.05 was used to determine statistical significance. Results: The cumulative OS and RFS at 3 years were 87% and 80%, respectively. The 5-year cumulative OS were 78% (Her-2 2+) and 73% (Her-2 3+) respectively. The 5-year RFS was 73%. The OS and RFS for patients with HR+ tumours were statistically significantly greater than those of HR- tumours (p=0.006 and p=0.024 respectively). The 3-year OS for HR+ and HR- was 92% and 77%. The 5-year OS for HR+ and HR- tumours was 89% and 55%, respectively. The RFS at 3 years for HR+ and HR- was 84 % and 69 % respectively, and 82% and 55%, respectively at 5 years. The Cox regression analysis showed stage and HR status had a contribution to RFS. The log rank testing showed HR+ has a significant contribution to both OS and RFS. Conclusion: The 5-year OS and RFS rates of our study were similar to those reported in long term prospective trials published in the pre-Trastuzumab era. In comparison to data published with the addition of Trastuzumab to treatment, our results were inferior. In addition, Her-2 positive HR+ tumors had superior outcomes to Her-2 positive HR- breast cancer tumors. Twenty-five years since the advent of Trastuzumab, at Groote Schuur Hospital does not have access. In a resource limited setting where Her-2 targeted agents for all indicated patients may not be possible, a case may be made for provision to patients with Her-2 HR- disease.