Methods are provided for identifying a cell exhibiting unregulated growth associated with methylation-silenced transcription of a suppressor of cytokine signaling (SOCS)/cytokine-inducible SH2 protein (CIS) family member (SOCS/CIS) gene such as the SOCS-1 gene. In addition, methods of treating a cancer patient, wherein cancer cells in the patient exhibit methylation-silenced transcription of SOCS/CIS gene such as a SOCS-1 gene, are provided, as are reagents for practicing such methods.