A method for determining the likelihood of breast cancer recurrence in a tamoxifen-treated, lymph node-negative, estrogen receptor-positive human breast cancer patient, the method comprising: (a) determining the expression levels of the RNA transcripts of GRB7, HER2, ER, PR, Bcl2, CEGP1, SURV, Ki.67, MYBL2, CCNB1, STK15, CTSL2, STMY3, CD68, GSTM1, and BAG1, or their expression products, in a biological sample containing tumour cells obtained from the patient; (b) creating the following gene subsets: (i) growth factor subset: GRB7 and HER2; (ii) estrogen receptor subset: ER, PR, Bcl2, and CEGP1; (iii) proliferation subset: SURV, Ki.67, MYBL2, CCNB1, and STK15; and (iv) invasion subset: CTSL2, and STMY3; (c) calculating a recurrence score for the patient by the following equation: RS = 0.23 to 0.70 × GRB 7 axisthresh − 0.17 to 0.55 × ERaxis + 0.52 to 1.56 × prolifaxisthresh + 0.07 to 0.21 × invasionaxis + 0.03 to 0.15 × CD 68 − 0.04 to 0.25 × GSTM 1 − 0.05 to 0.22 × BAG 1 wherein GRB7 axis = (0.45 to 1.35) x GRB7 + (0.05 to 0.15) x HER2; if GRB7 axis < -2, then GRB7 axis thresh =-2, and if GRB7 axis > -2, then GRB7 axis thresh = GRB7 axis; ER axis = ER + PR + Bcl2 + CEGP1)/4; prolifaxis = (SURV + Ki. 67 + MYBL2 + CCNB1 + STK15)/5; if prolifaxis < -3.5, then prolifaxisthresh =-3. 5, if prolifaxis > -3. 5, then prolifaxishresh = prolifaxis; and invasionaxis = (CTSL2 + STMY3)/2, wherein the individual contributions of the genes in, and are weighted by a factor of 0.5 to 1.5, and (d) creating a report providing the RS, wherein a higher RS indicates increased likelihood of breast cancer recurrence in said patient. (a) determining the expression levels of the RNA transcripts of GRB7, HER2, ER, PR, Bcl2, CEGP1, SURV, Ki.67, MYBL2, CCNB1, STK15, CTSL2, STMY3, CD68, GSTM1, and BAG1, or their expression products, in a biological sample containing tumour cells obtained from the patient; (b) creating the following gene subsets: (i) growth factor subset: GRB7 and HER2; (ii) estrogen receptor subset: ER, PR, Bcl2, and CEGP1; (iii) proliferation subset: SURV, Ki.67, MYBL2, CCNB1, and STK15; and (iv) invasion subset: CTSL2, and STMY3; (i) growth factor subset: GRB7 and HER2; (ii) estrogen receptor subset: ER, PR, Bcl2, and CEGP1; (iii) proliferation subset: SURV, Ki.67, MYBL2, CCNB1, and STK15; and (iv) invasion subset: CTSL2, and STMY3; (c) calculating a recurrence score for the patient by the following equation: RS = 0.23 to 0.70 × GRB 7 axisthresh − 0.17 to 0.55 × ERaxis + 0.52 to 1.56 × prolifaxisthresh + 0.07 to 0.21 × invasionaxis + 0.03 to 0.15 × CD 68 − 0.04 to 0.25 × GSTM 1 − 0.05 to 0.22 × BAG 1 wherein GRB7 axis = (0.45 to 1.35) x GRB7 + (0.05 to 0.15) x HER2; if GRB7 axis < -2, then GRB7 axis thresh =-2, and if GRB7 axis > -2, then GRB7 axis thresh = GRB7 axis; ER axis = ER + PR + Bcl2 + CEGP1)/4; prolifaxis = (SURV + Ki. 67 + MYBL2 + CCNB1 + STK15)/5; if prolifaxis < -3.5, then prolifaxisthresh =-3. 5, if prolifaxis > -3. 5, then prolifaxishresh = prolifaxis; and invasionaxis = (CTSL2 + STMY3)/2, wherein the individual contributions of the genes in, and are weighted by a factor of 0.5 to 1.5, and GRB7 axis = (0.45 to 1.35) x GRB7 + (0.05 to 0.15) x HER2; if GRB7 axis < -2, then GRB7 axis thresh =-2, and if GRB7 axis > -2, then GRB7 axis thresh = GRB7 axis; ER axis = ER + PR + Bcl2 + CEGP1)/4; prolifaxis = (SURV + Ki. 67 + MYBL2 + CCNB1 + STK15)/5; if prolifaxis < -3.5, then prolifaxisthresh =-3. 5, if prolifaxis > -3. 5, then prolifaxishresh = prolifaxis; and invasionaxis = (CTSL2 + STMY3)/2, (d) creating a report providing the RS, wherein a higher RS indicates increased likelihood of breast cancer recurrence in said patient.