The present invention relates generally to a method of diagnosing, prognosing or monitoring the development or progress of metastatic cancer, more particularly bone metastatic cancer. The method of the present invention more particularly provides a method for detecting metastatic cancer, or a predisposition thereto, by screening for the differential expression of a panel of genes which comprise an IRF7 binding site. In a related aspect, the present invention provides a method of therapeutically or prophylactically treating metastatic cancer, in particular bone metastatic cancer. More particularly, the present invention provides a means of therapeutically or prophylactically treating metastatic cancer by upregulating type I IFN levels.