Pattern of immunohistochemical expression of inherited breast cancer genes and collagen changes among African women with early breast cancer in Calabar, Nigeria

Abstract

The disparity in age of diagnosis and genetic testing of breast cancer among African women is a major cause of concern. The common inherited breast cancer genes like breast cancer gene 1 (BRCA1), breast cancer gene 2 (BRCA2) and Tumour protein 53 (TP53 or p53) as well as increase collagen deposition in the stroma predispose women to early breast cancer. The aim of this study was to establish the immunohistochemical expressions patterns of BRCA1, BRCA2, and p53 proteins as well as collagen changes in females with early onset breast cancers in University of Calabar Teaching Hospital. Data on breast tumours occurrences among 96 females were obtained from the Histopathology register. Ten randomly selected paraffin wax-embedded breast tissue blocks from Histopathology laboratory, University of Calabar Teaching Hospital were sectioned at 4 micrometer, stained histologically with haematoxylin and eosin, van Gieson for collagen fibres and immunohistochemically for BRCA1, BRCA2 and p53 protein expressions. Results showed that of the 96 women with breast tumours, 84.4% were ≤50 years while 15.6% were >50 years. Among the 10 tissues, 60% were BRCA1(-) and 40% BRCA1(+), 10% BRCA2(-) with 90% BRCA2(+), and 30% p53(-) with 70% p53(+) for protein expressions, although these were not significant. The BRCA1(+) tissues had significant lower staining intensity than BRCA2(+) (50.5±12.5; p=0.011) and p53(+) (53.8±8.6; p=0.040) counterparts. Majority of the breast tumours had significant increases in collagen fibre sizes consistent with type of tumour and grade of carcinoma but was irrespective of BRCA or p53 statuses. In conclusion, breast tumours are common among women below 50 years in Calabar and the selected early breast cancers were mostly characterized by negative expressions of BRCA1, positive expressions of BRCA2 and p53 proteins as well as increase deposition of collagen fibres. There is urgent need to carryout wider studies on these inherited breast cancer genes and collagen alterations to determine the risk of early breast cancer development.