A method for classifying cancer patients as eligible to receive cancer therapy with a small molecule inhibitor of Bcl-2 comprising determination of the presence or absence in a patient tissue sample of chromosomal copy number status at the chromosomal locus 13q14 comprising the microRNA's miR15a and miR16-1. The classification of cancer patients based upon the presence or absence of 13q14 loss or gain allows better selection of patients to receive chemotherapy with a small molecule Bcl-2 inhibitor such as N-(4-(4-((2-(4-chlorophenyl)-5,5-dimethyl-1-cyclohex-1-en-1- yl)methyl)piperazin-1-yl)benzoyl)-4-(((1R)-3-(morpholin-4-yl)-1-((phenylsulfanyl)methyl)propyl)amino)-3- ((trifluoromethyl)sulfonyl)benzenesulfonamide, and for monitoring patient response to this therapy.