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| Author | Claire Gatt |
| Abstract | Lung tumours are one of the most common causes of cancer death in the world, particularly in developed countries in both males and females. The prognosis is poor, with less than 15% of patients surviving 5 years after diagnosis. This poor prognosis results mostly due to a lack of efficient diagnostic methods for early detection and the lack of successful treatments for metastatic disease. It appears that hnRNP A2/B1, MCM2 and p53 are substantially over-expressed in lung premalignant and cancer cells and tissues. This study investigates these three markers on archived paraffin tissue blocks from the following diagnostic categories: normal bronchial epithelium, squamous metaplasia, dysplasia, and Squamous Cell Carcinoma (SCC). A total of 143 histology lung tissue cases and 60 bronchial lavage cell blocks were utilized in this study. The total 143 (histology blocks) consisted of 53 SCC, 10 dysplasia, 35 squamous metaplasia, and 35 normal bronchial epithelium. Retrospective cases included those lung cancer cases that had previous normal or abnormal bronchial tissue specimens. The search involved cases received between 1993 and 2005. The retrospective studies included 31 cases of the total 143. These 33 cases consisted of 6 normal tissue cases preceding SCC, 4 normal tissue cases preceding Adenocarcinoma, 1 normal tissue specimen preceding Small Cell Carcinoma, 11 squamous metaplasia cases preceding SCC, 4 squamous metaplasia specimens preceding Adenocarcinoma, 6 cases of dysplasia preceding SCC, and 1 dysplasia case preceding a Small Cell Carcinoma. There was a noted increase in positive immunoreactivity from normal and benign squamous metaplastic tissue towards abnormal tissue, that is, dysplastic and malignant cases (Z-Test). The % sensitivity and specificity for A2/B1 in Squamous Cell Carcinoma obtained from this study were 92% and 86%, for MCM2 96% and 89% and for p53, 96% and 83% respectively. The % sensitivity and specificity for A2/B1 in Adenocarcinoma obtained from this study were 38% and 86%, for MCM2 88% and 89% and for p53, 75% and 83% respectively. All the 6 dysplastic tissue specimens preceding SCC showed positive immunoreactivity with p53 and MCM2 markers, while 67% (4/6) showed positivity with A2/B1. Our observations were similar to previous studies, and may indicate that nuclear accumulation of p53, MCM2, and possibly cytoplasmic overexpression of hnRNP A2/B1 are early events in lung carcinogenesis. These markers may suggest their potential use in the identification of early lung changes in prospective large population studies. |
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| Key words | Medical Laboratory Science, Thesis, lung cancer, immunohistochemistry, tumour markers, p53 |