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Resectability of colorectal liver metastases: an evolving definition.

However, several issues remain to be resolved, including that of how to properly identify candidates for curative resection. The liver surgeon is frequently presented with four categories of CLM patient: those who are easily resectable; those who are borderline resectable; those who are unresectable but may be converted to resectable, and patients who are unlikely ever to be resectable. Proceeding straight to surgery has been the paradigm for the first group and chemotherapy or other non-resection liver-directed therapies have been reserved for the fourth group. The second and third groups have more recently been managed with a trial of neoadjuvant chemotherapy intended to downstage the tumour, allow for parenchymal-sparing hepatectomy and increase the probability of a margin-negative resection. Evidence from the European Organization for Research and Treatment of Cancer (EORTC) Intergroup 40983 trial demonstrated that in patients who underwent resection of up to four metastatic liver lesions, perioperative chemotherapy with FOLFOX [folinic acid (leucovorin), 5-FU, oxaliplatin] increased 3-year progression-free survival by 9.2% compared with surgery alone. 7 Recent refinements in surgical technique incorporating ablative techniques, portal vein embolization, staged resections and hepatic arterial pump therapy have allowed the definition of resectable CLM to evolve beyond the parameters of size, location and number of tumours. Presently, in order for CLM to be considered resectable, it must be removable with a negative margin and allow for the preservation of at least two contiguous, functional liver segments with intact portal and arterial inflow, venous outflow and biliary drainage. Additionally, as the future liver remnant (FLR) depends critically on functional liver parenchyma, it can be as small as 20% of total liver volume (TLV) in a patient with a normal liver, but an FLR injured by chemotherapy may need to represent 30% of TLV and one with fibrosis from cirrhosis may be required to represent as much as 40% of TLV. 8