A method of assessing the metastatic status of a primary breast tumour from an individual, said method comprising detecting the expression of IRF7 and one or more genes of said tumour, which genes comprise an IRF7 binding site in their promoter, selected from the lists consisting of: (a) ABL2 CMTM1 FAM120A IL15RA ADAM17 COPS5 FAM125A IRF7 ADSS CREB3 FAM82A2 IRGM AGRN CSF1 FOSL1 ITGB1 AIM1 CSF3 GBP2 ITGB2 AKAP2 CSRNP1 GBP4 ITGB5 ANKRD1 CSRP1 GBP7 JAG1 ANLN CTSH GCH1 JUNB ANXA1 CX3CL1 GCLM KLC1 ANXA5 CXCL1 GEM KLF5 APRT CXCL10 GLRX KPNB1 ARG2 CXCL2 GMFB LACTB ATF3 CXCL3 GNA13 LAMB1 ATP2A2 DAB2 GRINA LAMP1 ATP6V0B DDX18 GSDMD LAMP2 ATP6V1A DDX3X GUSB LAP3 ATRIP DDX60 HBEGF LCOR ATXN10 DEGS1 HDLBP LGALS3BP AZI2 DGUOK HERC6 LIPA B2M DHX58 HMGA2 LPIN2 BLZF1 DNAJA1 HMOX1 LY96 BMI1 DNAJB1 HNRNPF MAFG BST2 DUSP6 HRAS MAP1B BTF3 E2F3 HSPD1 MAP2K1 BZW1 EFR3A IER3 MAPKAPK3 CASP7 EGR2 IFI16 MAPRE1 CASP8 EHD4 IFI35 MARCH5 CCL2 EIF2B1 IFI44 MCFD2 CCRL2 EIF2S1 IFIH1 MCL1 CD274 EIF5 IFIT1B METAP2 CD38 EIF5B IFIT2 MFSD10 CD44 ELK3 IFIT3 MGAT2 CD9 EMP2 IFITM1 MLF1 CDKN1A EPS8 IFITM2 MRPL19 CFLAR ERRFI1 IFITM3 MSMO1 CKLF ESD IGFBP4 MTHFD1 CKLF-CMTM1 EXTL2 IL11 NAMPT CMPK2 F3 IL13RA1 NAMPTL NEK2 PPM1B SAT1 UBE2N NMI PPP2R2A SDCBP UBE2V2 NRAS PPT1 SLC2A1 UQCRB NUB1 PRKAR1A SLC30A1 USP18 OAS1 PROCR SLC39A14 USP4 OASL PSMA4 SLC6A6 USP41 OGFR PSMB10 SLCO2A1 WARS P4HA1 PSMB2 SOCS3 WDFY1 PAFAH1B2 PSMB8 SPTLC2 WWP1 PAK2 PSMB9 SQLE XAF1 PALM2- PSMC1 SRSF3 YWHAZ AKAP2 PSMC2 SSR1 ZBTB41 PARP12 PSMC6 ST13 ZC3HAV1 PCGF5 PSME1 STAT1 ZFP36 PCMT1 PSME2 STK3 ZNFX1 PDGFRL PTGS1 TCEA1 ZWINT PDIA6 PTGS2 TIPARP ACSL4 PDXK PTPRK TK1 ARG1 PEAK1 PYHIN1 TLK2 ATP6V1B2 PEX19 RAB31 TLR3 CALD1 PGD RAB7A TM4SF1 CD86 PGK1 RAP1B TMA16 CFP PGS1 RASA4 TMEM106A CSDE1 PI4K2B RASA4B TNFAIP2 CTSS PITPNM1 RBBP4 TNFAIP3 CXCL9 PLAUR RCAN1 TOR3A HNMT PLEC RHOD TPM1 IFI202B PLOD2 RNF19B TPM4 LER3 PLS3 RNF2 TRAFD1 LGMN PLSCR1 RSAD2 TREX1 NIPA2 PLSCR2 RTP4 TRIOBP RUNX3 POLR2F RUNX1 TRIP12 TGIF1 PPID SAMHD1 TUBA3C THBS1 PPIH SAP18 TUBA3D or (b) ACSL4 CSF3 IFI44 LGMN ARG1 CTSS IFI44L NIPA2 ATP6V1B2 CXCL9 IFIT1 NIPAL1 BST2 DHX58 IFIT1B PYHIN1 CALD1 DSP IFIT3 RSAD2 CD86 GCH1 IL15 RTP4 CFP HNMT IRF7 RUNX3 CMPK2 IFI16 IRGM TGIF1 CSDE1 IFI202B LER3 THBS1 CSF2RB IFI35 LGALS3BP TLR3 wherein a decreased level of expression of IRF7 and one or more genes relative to the level of expression of said IRF7 and one or more genes in a corresponding non-metastatic breast tumour is indicative of a metastatic phenotype of said tumour. (a) ABL2 CMTM1 FAM120A IL15RA ADAM17 COPS5 FAM125A IRF7 ADSS CREB3 FAM82A2 IRGM AGRN CSF1 FOSL1 ITGB1 AIM1 CSF3 GBP2 ITGB2 AKAP2 CSRNP1 GBP4 ITGB5 ANKRD1 CSRP1 GBP7 JAG1 ANLN CTSH GCH1 JUNB ANXA1 CX3CL1 GCLM KLC1 ANXA5 CXCL1 GEM KLF5 APRT CXCL10 GLRX KPNB1 ARG2 CXCL2 GMFB LACTB ATF3 CXCL3 GNA13 LAMB1 ATP2A2 DAB2 GRINA LAMP1 ATP6V0B DDX18 GSDMD LAMP2 ATP6V1A DDX3X GUSB LAP3 ATRIP DDX60 HBEGF LCOR ATXN10 DEGS1 HDLBP LGALS3BP AZI2 DGUOK HERC6 LIPA B2M DHX58 HMGA2 LPIN2 BLZF1 DNAJA1 HMOX1 LY96 BMI1 DNAJB1 HNRNPF MAFG BST2 DUSP6 HRAS MAP1B BTF3 E2F3 HSPD1 MAP2K1 BZW1 EFR3A IER3 MAPKAPK3 CASP7 EGR2 IFI16 MAPRE1 CASP8 EHD4 IFI35 MARCH5 CCL2 EIF2B1 IFI44 MCFD2 CCRL2 EIF2S1 IFIH1 MCL1 CD274 EIF5 IFIT1B METAP2 CD38 EIF5B IFIT2 MFSD10 CD44 ELK3 IFIT3 MGAT2 CD9 EMP2 IFITM1 MLF1 CDKN1A EPS8 IFITM2 MRPL19 CFLAR ERRFI1 IFITM3 MSMO1 CKLF ESD IGFBP4 MTHFD1 CKLF-CMTM1 EXTL2 IL11 NAMPT CMPK2 F3 IL13RA1 NAMPTL NEK2 PPM1B SAT1 UBE2N NMI PPP2R2A SDCBP UBE2V2 NRAS PPT1 SLC2A1 UQCRB NUB1 PRKAR1A SLC30A1 USP18 OAS1 PROCR SLC39A14 USP4 OASL PSMA4 SLC6A6 USP41 OGFR PSMB10 SLCO2A1 WARS P4HA1 PSMB2 SOCS3 WDFY1 PAFAH1B2 PSMB8 SPTLC2 WWP1 PAK2 PSMB9 SQLE XAF1 PALM2- PSMC1 SRSF3 YWHAZ AKAP2 PSMC2 SSR1 ZBTB41 PARP12 PSMC6 ST13 ZC3HAV1 PCGF5 PSME1 STAT1 ZFP36 PCMT1 PSME2 STK3 ZNFX1 PDGFRL PTGS1 TCEA1 ZWINT PDIA6 PTGS2 TIPARP ACSL4 PDXK PTPRK TK1 ARG1 PEAK1 PYHIN1 TLK2 ATP6V1B2 PEX19 RAB31 TLR3 CALD1 PGD RAB7A TM4SF1 CD86 PGK1 RAP1B TMA16 CFP PGS1 RASA4 TMEM106A CSDE1 PI4K2B RASA4B TNFAIP2 CTSS PITPNM1 RBBP4 TNFAIP3 CXCL9 PLAUR RCAN1 TOR3A HNMT PLEC RHOD TPM1 IFI202B PLOD2 RNF19B TPM4 LER3 PLS3 RNF2 TRAFD1 LGMN PLSCR1 RSAD2 TREX1 NIPA2 PLSCR2 RTP4 TRIOBP RUNX3 POLR2F RUNX1 TRIP12 TGIF1 PPID SAMHD1 TUBA3C THBS1 PPIH SAP18 TUBA3D or (b) ACSL4 CSF3 IFI44 LGMN ARG1 CTSS IFI44L NIPA2 ATP6V1B2 CXCL9 IFIT1 NIPAL1 BST2 DHX58 IFIT1B PYHIN1 CALD1 DSP IFIT3 RSAD2 CD86 GCH1 IL15 RTP4 CFP HNMT IRF7 RUNX3 CMPK2 IFI16 IRGM TGIF1 CSDE1 IFI202B LER3 THBS1 CSF2RB IFI35 LGALS3BP TLR3