GSTM1 and ductal breast carcinoma in situ: In an effort to develop a DCIS-specific assay, Oncotype Dx® was reduced to 12 genes (Ki-67, STK15, survivin, CCNB1, MYBL2, PR, GSTM1, ACTB, GAPDH, RPLPO, GUS, and TFRC) to create the DCIS recurrence score.