SIRFLOX: Randomised phase III trial comparing first-line mFOLFOX6 ± bevacizumab (bev) versus mFOLFOX6 ± bev + selective internal radiation therapy (SIRT) in patients with metastatic colorectal cancer (mCRC) - analysis by presence or absence of extra-hepatic metastases, bev treatment and site of first progression (#20)