Study of histological grading by modified bloom richardson grading system and ER, PR, HER-2/neu status in invasive breast carcinoma by diagnostic immunohistochemistry using tissue microarray

BACKGROUND: Breast carcinoma, the most common malignant tumour among women contributes to a significant proportion of all cancers in women worldwide. It was graded based on levels of nuclear pleomorphism, tubular formation and mitotic index. The commonly used predictive immunohistochemical markers are estrogen receptors, progesterone receptors and HER2/neu status. In our study we use microarray technique where small representative tissue samples from many cases were assembled on a single histology slide and subjected to Immunohistochemical analysis. AIMS AND OBJECTIVES: To study histological grading by Modified Bloom Richardson grading system and ER, PR & HER 2/ neu status in invasive breast carcinoma by diagnostic immunohistochemistry using Manual Tissue Microarray and assess the cost-effectiveness of IHC done on TMA slides. MATERIALS AND METHODS: 50 cases of invasive breast carcinoma were included in the study. Histopathological examination of the haematoxylin and eosin stained slides were done and the tumour was graded according to Modified Bloom Richardson grading system. A standard method of microarray preparation was done. First the design for TMA construction was laid out. Paraffin embedded tissue blocks were collected and the areas of invasive carcinoma were cored from donor blocks and transferred to the recipient blocks using bone marrow needle. Thus tissue microarray was constructed manually. Immunohistochemical analysis using ER, PR and Her2/neu were done for all these cases. Evaluation was done with Allred scoring system for ER and PR status, and ASCO guidelines for HER2/neu status. RESULTS: Of the 50 patients analysed, majority were invasive ductal carcinoma (84%). Majority of the invasive breast carcinoma were of MBR grade II (50%) followed by grade III tumors (42%) and grade I tumors (8%). Among 50 cases, ER and PR were positive in 24 cases (48%) and 31 cases (62%) respectively. HER-2/neu expression was seen in 25 cases (50%). A statistically significant correlation was noted between histologic grading and ER, PR and HER2/neu status. The tissue microarray uses only one seventh of the reagent consumed by conventional immunohistochemistry. CONCLUSION: The process of immunohistochemistry using tissue microarray obviates the need for control and standardisation. This allows the study of different cases on a single slide, thus reducing the amount of reagent, duration and labour of the procedure and making it cost effective. Tissue loss due to technical problems can be overcome by following standard protocols or by obtaining more number of tissue cores