Impact of primary tumor side on clinical outcomes of first-line cetuximab plus FOLFOX-4 in RAS wild-type metastatic colorectal cancer.

Aim: To examine the impact of tumor sidedness on clinical outcomes in Chinese patients with metastatic colorectal cancer treated with folinic acid/fluorouracil/oxaliplatin (FOLFOX-4) ± cetuximab in the TAILOR trial. Patients & methods: Clinical data from 391 patients were evaluated for tumor sidedness. Results: Patients with left-sided tumors who received cetuximab plus FOLFOX-4 had a significantly longer overall survival (medians: 22.0 vs 18.3 months; p = 0.007) and progression-free survival (medians: 9.3 vs 7.9 months; p = 0.006) compared with FOLFOX-4 alone. Overall survival (medians: 11.5 vs 9.4 months; p = 0.664) and progression-free survival (medians: 7.4 vs 4.5 months; p = 0.068) also improved in patients with right-sided tumors. Conclusion: Adding cetuximab to first-line FOLFOX-4 in patients with metastatic colorectal cancer improved clinical outcomes irrespective of primary tumor side.