Treatment strategies in colorectal cancer patients with initially unresectable liver-only metastases: The randomized phase III CAIRO5 study of the Dutch Colorectal Cancer Group.

TPS3622 Background: Colorectal cancer patients with unresectable liver-only metastases may be cured after downsizing of metastases by neoadjuvant systemic therapy. However, the optimal neoadjuvant induction regimen has not been defined, and the lack of consensus on criteria for (un)resectability complicates the interpretation of published results. Methods: CAIRO5 is a multicenter, randomized, phase III clinical study. Colorectal cancer patients with initially unresectable liver-only metastases are eligible, and will not be selected for potential resectability to avoid selection bias. The unresectability status is prospectively assessed by a central panel consisting of at least one radiologist and three liver surgeons, and defined as no radical resection possible in one session with resection only. Tumors of included patients will be tested for RAS and BRAF (for stratification purpose) mutation status. Patients with RAS wild type tumors are treated with doublet chemotherapy (FOLFOX/FOLFIRI, choice of inves...