Criteria for Liver Metastasectomy in Rectal Cancer
Liver metastasectomy should be performed when complete R0 resection of all macroscopic disease with clear margins is technically feasible while maintaining adequate hepatic function (≥30% remnant liver volume or minimum 2 segments), the primary rectal tumor has been or can be resected with curative intent (R0), and no unresectable extrahepatic disease is present. 1
Core Technical Resectability Criteria
The fundamental requirements for proceeding with liver metastasectomy include:
- Complete R0 resection must be achievable - all macroscopic disease must be removable with negative margins, regardless of number, size, or bilobar distribution 1
- Adequate remnant liver volume - approximately one-third of standard liver volume or minimum of two segments must remain functional 1
- Primary tumor control - the rectal primary must have been resected for cure (R0) or be resectable with curative intent 1
- Medical fitness - patient must be able to tolerate major hepatic surgery as determined by the hepatobiliary surgeon and anesthesiologist 1
Disease Distribution Considerations
Number and location of metastases do not constitute absolute contraindications - patients with solitary, multiple, and bilobar disease are all candidates for resection if technical criteria are met 1. The 2025 EORTC consensus specifically emphasizes that resectability is not limited by traditional factors like number (<4) or size (>5 cm) 1.
Extrahepatic Disease Parameters
Limited extrahepatic disease does NOT preclude liver resection in select circumstances 1:
- Resectable/ablatable pulmonary metastases are acceptable 1
- Resectable isolated extrahepatic sites (spleen, adrenal, resectable local recurrence) are acceptable 1
- Oligometastatic disease defined as maximum 5 metastatic lesions amenable to resection/ablation in up to 2 different organs 1
- Local direct extension to diaphragm or adrenal that can be resected 1
Uncontrollable extrahepatic disease represents an absolute contraindication to liver resection 1.
Conversion to Resectability
For initially unresectable liver metastases, re-evaluation for resection should occur after 2 months of preoperative chemotherapy and every 2 months thereafter 1. The most active available induction treatment should be chosen, with chemotherapy selection based on molecular profile 1:
- pMMR/MSS, RAS/BRAF wild-type, left-sided tumors: chemotherapy plus anti-EGFR monoclonal antibody (doublet preferred over triplet) 1
- pMMR/MSS, RAS/BRAF wild-type, right-sided tumors: triplet chemotherapy (FOLFOXIRI or FOLFIRINOX) 1
- pMMR/MSS, RAS/BRAF mutant tumors: triplet chemotherapy plus bevacizumab 1
When hepatic metastatic disease is not optimally resectable based on insufficient remnant liver volume, approaches using preoperative portal vein embolization or staged liver resections can be considered 1.
Rectal Cancer-Specific Considerations
Timing and Sequencing
In patients with synchronous liver metastases from rectal cancer, pelvic radiotherapy should be considered if indicated by primary tumor stage to reduce local recurrence risk 1. The most threatening site guides treatment sequence 2.
If simultaneous resection is not feasible (poor performance status or requiring major surgery at both sites), resection/ablation of liver metastases followed by resection of the primary tumor (liver-first approach) should be preferred for patients with synchronous disease and no symptoms from the primary 1, 3.
Synchronous resection is generally not recommended outside high-volume centers, though management of accessible small metastases detected preoperatively may be discussed with the liver center for consideration of combined resection 1.
Perioperative Chemotherapy
For patients undergoing curative-intent resection following downsizing by <4 months of systemic chemotherapy, continue treatment for total duration of 6 months (including preoperative and postoperative) 1. Surgery should occur 5-10 weeks following full-dose neoadjuvant chemoradiation for the rectal primary 1.
Alternative and Adjunctive Approaches
Ablative techniques may be considered alone or in conjunction with resection when all original sites of disease are amenable to ablation or resection 1. If deemed medically unfit for surgery, patients should be considered for ablative therapy 1.
For bilobar disease, either one- or two-stage hepatectomy can be considered depending on size, location, number of lesions, and local expertise, with one-stage resection preferred whenever feasible 1.
Critical Pitfalls to Avoid
Debulking resection (less than R0) is not recommended - all macroscopic disease must be removable 1. Biopsy of hepatic lesions should not be performed without discussion with the regional hepatobiliary unit 1. Lesions discovered at operation should not be biopsied 1.
Complete metabolic response on PET-CT should not prevent surgical resection - lesions must still be removed based on original anatomical location to prevent relapse 4.
Re-resection can be considered in select patients with recurrent disease after prior curative-intent liver surgery 1.
Decision-Making Framework
All resectability determinations should be made by the regional hepatobiliary unit in multidisciplinary consultation including colorectal surgeons, hepatobiliary surgeons, medical oncologists, and radiologists 1, 3. The liver surgeon and anesthetist make the final clinical decision regarding fitness for surgery and technical feasibility 1.