Conversely, PFS (PFS after treatment with cetuximab for left-sided lesions was 12 months versus 7.7 months for right-sided lesions) and OS (OS after treatment with cetuximab for left-sided lesions was 37.5 months versus 16.4 months for right-sided lesions) were shorter in KRAS wt patients with right-sided primary CRC who were treated with cetuximab [43]. The gene discussed is KRAS; the disease is colorectal carcinoma.