EGFR and neoplasm: A previous study investigating 144 RAS wild-type mCRC patients found that of the 21 patients with primary and paired metastasis, in 38% of cases examined both the primary tumour and related metastasis were EGFR-negative (staining present in less than 5% of tumour cells or staining intensity of 0) and 48% (10/21) of patients had discordance in the expression of wtEGFR in the primary tumours and related metastasis [93].