IMMUNOHISTOCHEMICAL EXPRESSION OF BRCA2 PROTEIN AND ALLELIC LOSS AT THE BRCA2 LOCUS IN PROSTATE-CANCER

Many epidemiological studies have reported an association between brea st and prostate cancer. BRCA2 functions as a tumour-suppressor gene in about 35% of large familial breast-cancer clusters; its role in the p athogenesis of sporadic breast cancer is less clear. We have evaluated immunohistochemical expression of BRCA2 protein and allelic loss of m arkers at the BRCA2 locus in tissue derived both from sporadic and fro m familial cases of prostate cancer. Immunohistochemical analysis was performed in 167 paraffin-embedded archival specimens. Normal prostate and 75% (120/160) of prostate-cancer tissue did not express BRCA2 pro tein. However, 25% (40/160) of cancer cases did express patchy stainin g; of these, 17% (27/160) expressed positive nuclear staining in norma l glandular tissue adjacent to tumour (either in addition to, or, inde pendent of tumour). Allelic loss is the hallmark of a tumour-suppresso r gene. Markers flanking (D13S267, D13S260) and within (D13S171) the B RCA2 gene indicated allelic lose in at least one locus in 23% (17/73) of tumours analyzed. There was no difference in the rates of allelic l oss between sporadic and familial tumours, nor was there any associati on between immunohistochemical staining and allelic loss. Although imm unohistochemical staining provided no useful prognostic information, a llelic loss at BRCA2 was shown in univariate analysis to be associated with poorer survival (log-rank test, p = 0.046). Int. J. Cancer 78:1- 7, 1998. (C) 1998 Wiley-Liss, Inc.