1. A method for predicting the likelihood of a beneficial response to chemotherapy of a subject diagnosed with cancer, comprising (a) quantitatively determining, in a biological sample comprising cancer cells obtained from said subject, the value of one or more of the following variables: (i) Recurrence Score, (ii) ESR1 Group Score; (iii) Invasion Group Score; (iv) Proliferation Group Threshold Score; and (v) the expression level of the RNA transcript of at least one of MYBL2 and SCUBE2, or the corresponding expression product, wherein (b1) for every unit of an increase in the value of one or more of (i), (iii), (iv), or the expression level of the RNA transcript of MYBL2, or the corresponding expression product, said subject is identified to have a proportionately increased likelihood of a beneficial response to said chemotherapy; and (b2) for every unit of an increase in the value of (ii) or the expression level of the RNA transcript of SCUBE2, or the corresponding expression product, said subject is identified to have a proportionately decreased likelihood of a beneficial response to chemotherapy; and (b3) for every unit of an increase in the value of (i), said subject is identified as having an increased likelihood of a beneficial response to chemotherapy, as measured by a reduced risk of breast cancer recurrence; wherein 
 ESR 1 Group Score=( ESR 1 +PGR+BCL 2 +SCUBE 2)/4; 
 Invasion Group Score=( CTSL 2 +MMP 11)/2; 
 GRB 7 Group Score=0.9 ×GRB 7+0.1 ×ERBB 2; GRB7 Group Threshold Score equals 8 if the GRB7 Group Score is less than 8 and equals the GRB7 Group Score if the GRB7 Group Score is 8 or more 
 Proliferation Group Score=( BIRC 5 +MKI 67 +MYBL 2 +CCNB 1 +STK 6)/5; Proliferation Group Threshold Score equals 6.5, if the Proliferation Group Score is less than 6.5; and equals the Proliferation Group Score, if the Proliferation Group Score is 6.5 or more, and RS = { 0 ⁢ if ⁢ ⁢ 20 × ( RS U - 6.7 ) < 0 20 × ( RS U - 6.7 ) ⁢ if ⁢ ⁢ 0 ≤ 20 × ( RS U - 6.7 ) ≤ 100 100 ⁢ if ⁢ ⁢ 20 × ( RS U - 6.7 ) > 100 wherein RSu=0.47×GRB7 Group Threshold Score −0.34×ESR1 Group Score +1.04×Proliferation Group Threshold Score +0.10×Invasion Group Score +0.05×CD68 −0.08×GSTM1 −0.07×BAG1 where the gene symbols in the equations represent the expression levels of the RNA transcripts of the respective genes, or their expression products, and the individual contributions of the genes in variables (i), (ii), (iii), and (iv) are weighted by a factor of 0.5 to 1.5; and wherein every individual gene and every gene present in any of said variables can be substituted by another gene that coexpresses with said gene in said cancer with a Pearson correlation coefficient of ≧0.5.