Because normal pancreatic and kidney cells coexpress both MUC1-TM and MUC1-ARF, thus typifying the MUC1 expression pattern of a normal epithelial cell (both MUC1-TM and MUC1-ARF), it would appear as if the subtype of breast cancers that also coexpress both MUC1-TM and MUC1-ARF, a signature MUC1-expression pattern reflecting the normal epithelial cell, may have a better prognosis than those tumors that express only MUC1-TM. Here, MUC1 is linked to breast cancer.