Methods and materials are described for use in clinical and research applications directed to cancers. Products include binding arrays e.g., hybridization or other specific binding arrays such as genomic or proteomic microarrays. The binding arrays include binding agents developed based upon the recognition of heterogeneity between left-arising and right-arising breast cancer tumors. The arrays can include as binding agents materials that bind transcripts or proteins that are over-expressed in only one of or in both of left-arising or right-arising breast cancer tumors.