Browsing by Author "Mosa'ati, 'Inoke Maka"

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    The impact of Synaptophysin-Ki67 and Chromogranin A-Ki67 dual IHC staining in the assessment of the Ki67 Proliferative Index when grading well-differentiated gastrointestinal neuroendocrine tumours (WDGI NETs) : a thesis presented to the Massey University College of Health in partial fulfilment of the requirements for the Master of Health Science specializing in Medical Laboratory Research at Massey University, Distance Learning, Manawatu, New Zealand
    (Massey University, 2024) Mosa'ati, 'Inoke Maka
    A significant step in the assessment of the Ki67 proliferative index (KPI) when grading well-differentiated gastrointestinal neuroendocrine tumours (WDGI NETs) is the manual counting of active neoplastic cells against the surrounding population of cells. This step is often challenging due to the presence of background stromal lymphocytes and entrapped non-neoplastic glands which can contain proliferating cells. As a result, pathologists can have difficulty distinguishing between tumour cells and non-tumour cells which leads to inaccurate assessment of KPI. This is especially a problem when grading tumours close to the established category cutoffs. Studies show that this problem is challenging to overcome with or without the use of computational tools and automated image analysis to improve assessments made using manual image analysis. Benefits of image analysis solutions are not able to be replicated consistently, leading to a lack of uniformity in reporting. Some solutions were also expensive or not user friendly as they required technical expertise, time and skills to undertake. The aim of this study was to overcome limitations in the Ki67 single stain approach by qualitatively and quantitatively examining the positive impact of dual (or double) immunohistochemistry staining in the assessment of the Ki67 proliferative index (KPI) when grading well-differentiated gastrointestinal neuroendocrine tumours (WDGI NETs). The study successfully optimized and validated Synaptophysin-Ki67 and Chromogranin A-Ki67 double stain approaches, resulting in a reproducible and reliable methodology for use in a clinical diagnostic setting. The first finding of this study was confirmation that Synaptophysin-Ki67 and Chromogranin A-Ki67 reproduced the results (diagnostic grades) of the gold standard ‘Ki67-only’ stain. Validation of new procedures is essential for diagnostic accreditation. From a qualitative perspective, the double staining methods were superior in showing the identity of Ki67 positive tumour cells undergoing proliferation. Furthermore, the double stains were significantly more efficient from the perspective of pathologist time. In this regard they outperformed the gold standard method. This was a second key finding to justify further exploration of which double stain method might be the best to adopt. From a quantitative perspective, the double staining methods, on average, produced a less variable assessment of KPI than Ki67 alone. When the subset of tumour biopsy samples was compared with the resected tumour samples, regardless of tumour location in the gastrointestinal system, the KPI assessment results were significantly higher for the biopsy sample subset stained using a dual stain approach. The Ki67 stain alone could not replicate this finding. When the subset of upper gastro-intestinal (GI) tract samples was compared with lower GI tract samples, regardless of specimen type, the KPI assessment results were significantly higher for the upper GI tract subset using the dual stain approach. The Ki67-only stain could duplicate this trend but without statistical significance. The subset analysis provided further evidence for the utility of the dual stain approach in terms of precision. More research is now required to understand the implications of these differences and if better statistical models are required to understand the performance of biopsies in determining the most accurate diagnosis for WDGI NETs. The findings of this research will further encourage the use of dual markers to improve the visualization of tumour cells by making it easier to count Ki67 positive nuclei in neoplastic cells, thereby positively benefiting grading assessment for WDGI NETs and improving diagnostic accuracy. This study shows the utility of double stains as a platform for further research. For example, by looking retrospectively at a subset of cases where grade determination and clinical outcomes were in conflict for the Ki67-only stain method and by looking prospectively at how dual stain methods might provide better prognostic and therapeutic recommendations. The goal for future research is to improve case management and patient survival with the input of the oncology and pathology team. Dual stain techniques are very likely to have broader application to neuroendocrine tumours in general.