Table 1.

Criteria used to define patients as initially unresectable

Study	Year of publication	Country	Setting	Study period	Criteria for initial unresectability of CLM	Criteria for selection for TSH
Turrini et al.25	2012	France	Retrospective	2000–2010	Specific criteria Inability to resect all CLM with tumour-free margins saving 25–30% of remnant liver volume	Not stated
Tsim et al.26	2011	UK	Prospective	2003–2006	Not stated	Bilobar CLM in which the left hemiliver can be cleared of metastases during stage 1 resection and in which 25% of functional liver volume can be preserved after right PVE and right/extended right hepatectomy
Narita et al.27	2011	France	Retrospective	1996–2009	Non-specific criteria Multiple and bilobar CLM in which it is impossible to remove all CLM with safe margins during a single hepatectomy procedure	Multiple and bilobar CLM in which: (i) clearance of the left hemiliver is feasible during stage 1; (ii) the left hepatic vein and pedicle are not invaded, and (iii) FLR volume before PVE is < 30–40% of total functional liver volume
Muratore et al.24	2011	Italy	Prospective	1997–2009	Non-specific criteria Bilobar CLM in which a radical resection by single hepatectomy is not possible	Not stated
Brouquet et al.23	2011	USA	Retrospective	2002–2010	Not stated	Chemotherapy-responsive bilobar CLM in which limited resection can clear the less affected side of the liver before the patient undergoes a planned extended contralateral liver resection
						Surgeon must be able to resect all CLM while preserving a sufficient FLR (20% of total liver volume) and adequate vascular inflow and outflow
Bowers et al.22	2011	UK	Retrospective	2004–2010	Specific criteria Not possible to resect all disease while retaining an FLR volume ≥ 0.5% of body weight with preserved vascular inflow and outflow and biliary drainage	Not stated
Tsai et al.21	2010	USA and Portugal	Retrospective	1994–2008	Specific criteria Not possible to resect all CLM while: (i) sparing two adjacent liver segments; (ii) preserving vascular inflow and outflow, and (iii) maintaining adequate remnant liver volume	Not stated
Wicherts et al.20	2008	France	Prospective	1992–2007	Specific criteria Inability to resect all CLM with tumour-free margins and save 25–30% of liver volume	Non-specific criteria indicating that complete removal of CLM is possible in two sequential resections
Pamecha et al.19	2008	UK	Prospective	1999–2005	Specific criteria Bilobar CLM in which it is impossible to remove all CLM while leaving remnant liver of 30%	Non-specific criteria indicating that resection of CLM with clear margins can be achieved leaving sufficient FLR volume
Tanaka et al.18	2007	Japan	Retrospective	1992–2004	Specific criteria with Yamanaka prediction scorea	Specific criteria with Yamanaka prediction score of > 60

^aYamanaka prediction score = − 84.6 + 0.933A + 1.11B + 0.999C, where A = resection fraction (%) calculated from computed tomography volumetry; B = indocyanine green retention rate at 15 minutes, and C = the age of the patient.

CLM, colorectal liver metastasis; PVE, portal vein embolization; FLR, future liver remnant; TSH, two-stage hepatectomy.