Assays using binding studies involving function of BRCA1a protein have use for diagnosis and for evaluation of possible tumorogenicity of agents, particularly estrogenic agents. The assays do not rely on use of a probe for only specific sequences, but on effects of known and unknown or not previously studied sequences (consequence of genetic changes) or posttranslational modification of BRCA1 proteins (as a consequence of epigenetic changes) as seen in hereditary and sporadic cancers.