Metastatic colorectal cancer and liver referral

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Colorectal cancer reaches the liver through portal venous drainage, but hepatic metastasis does not by itself establish palliative intent. Resectability means that all visible disease can be cleared by resection or ablation while retaining a sufficiently perfused and drained functioning liver remnant. Lesion number alone cannot make that judgement, so suspected liver-limited disease should reach a hepatobiliary MDT early.

Contrast CT defines whole-body disease and dedicated liver MRI clarifies lesion count, segments and vascular relationships. Treatment may be bowel-first, liver-first, simultaneous or staged and may use systemic therapy to test biology or convert anatomy. RAS and BRAF V600E testing guides targeted systemic options, while MMR or MSI status identifies possible immunotherapy pathways; biomarkers complement rather than replace anatomical review. One concrete NICE-linked consequence is that encorafenib with cetuximab is an option for BRAF V600E mutation-positive metastatic colorectal cancer after previous systemic treatment.

Key points

Liver is the commonest metastatic site because portal venous drainage carries tumour cells from the colon.
Resectability depends on clearing all disease while preserving an adequate functioning liver remnant, not simply lesion number.
High-quality liver imaging defines segmental relationships to vessels and remaining parenchyma.
All suitable metastatic cancers require RAS and BRAF V600E testing to guide systemic options; mismatch-repair status is also relevant.
Synchronous primary and liver disease may be treated bowel-first, liver-first or simultaneously after joint planning.
Extrahepatic disease does not automatically preclude local treatment but requires realistic whole-disease assessment.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Haematogenous dissemination from a colorectal primary

Invasive tumour cells enter mesenteric venous channels, survive portal circulation and seed hepatic sinusoids, where selected clones establish metastatic deposits.

Metastatic tumour biology

RAS, BRAF, MMR and other clonal alterations influence growth, treatment sensitivity and prognosis; biology may differ between the primary and later metastatic sites.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Portal first-pass spread
Venous effluent from most of the colon and upper rectum traverses the liver, explaining why liver is a frequent first metastatic organ.
2
Parenchymal replacement and vascular proximity
Growing deposits replace functioning hepatocytes and may abut portal pedicles, hepatic veins or bile ducts, limiting clearance while preserving an adequate remnant.
3
Clonal response and resistance
Systemic treatment removes sensitive clones but may select resistant disease; interval response without new lesions provides biological information alongside technical downstaging.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Portal pattern of hepatic spread

Colonic and superior rectal venous drainage reaches the liver first, making hepatic metastases common; low rectal drainage can also favour early lung involvement.

Resectability is anatomical and physiological

The team must be able to clear all treatable disease while retaining adequate functioning liver volume, inflow, outflow and biliary drainage in a patient fit for the sequence.

Potentially convertible disease

Bilobar or vessel-adjacent metastases may become resectable after response, portal-vein embolisation, staged surgery or combined ablation, so an initial scan is not always a final verdict.

Primary-tumour symptoms affect sequence

Obstruction, perforation or major bleeding from the colorectal primary may require diversion, stenting or resection before a liver-directed plan that would otherwise take priority.

Whole-disease burden matters

Lung, peritoneal and nodal metastases do not automatically forbid local liver treatment, but every site must be mapped and judged controllable within one realistic treatment intent.

Red flags requiring action

Distension with vomiting and obstipation, jaundice with fever and rigors, or acute deterioration during systemic therapy needs same-day assessment rather than waiting for response imaging.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Contrast CT chest, abdomen and pelvisFirst step
Why
Stage the primary, liver, lung, peritoneum and nodes as one disease process.
Interpretation and limitations
Record synchronous sites and primary complications; small liver lesions or apparent vessel contact may need dedicated MRI before resectability is decided.
02
Liver MRI with hepatobiliary contrast
Why
Characterise and map hepatic lesions by segment and vascular or biliary relationship.
Interpretation and limitations
MRI can reveal CT-occult deposits and determine whether parenchymal-sparing resection, ablation, staged surgery or remnant augmentation is feasible.
03
RAS and BRAF V600E mutation testing
Why
Select people with metastatic colorectal cancer who may benefit from particular targeted systemic therapies.
Interpretation and limitations
A mutation affects drug choice and prognosis but cannot establish whether liver deposits are technically resectable.
04
Mismatch-repair or microsatellite-instability testing
Why
Identify dMMR or MSI-high biology relevant to Lynch assessment and immunotherapy options.
Interpretation and limitations
Interpret in the clinical and treatment-line context; MMR status is a biological result, not a map of tumour burden.
05
Serial cross-sectional imaging and CEA
Why
Assess response, progression and renewed resectability after each treatment phase.
Interpretation and limitations
CEA is useful only alongside symptoms and comparable imaging; a biochemical fall cannot prove margin clearance or absence of new lesions.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Simple cyst or haemangioma

Benign focal lesions may coexist with colorectal cancer; characteristic enhancement and hepatobiliary MRI features prevent incorrect metastatic staging.

Primary hepatobiliary malignancy

Cholangiocarcinoma and hepatocellular carcinoma have different risk factors, imaging patterns and pathology, so atypical lesions need hepatobiliary radiology review.

Abscess or inflammatory lesion

Fever, inflammatory markers, recent infection and diffusion or enhancement pattern may suggest abscess, although necrotic metastasis can look similar and needs multidisciplinary interpretation.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Worked case: unilobar liver-limited metastasesPreserve curative options through joint colorectal and liver planningFirst stepA fit 62-year-old has a non-obstructing sigmoid adenocarcinoma and three colorectal metastases confined to liver segments V, VI and VII. CT shows no extrahepatic disease and bilirubin is normal.

1Complete colonoscopy, primary-tumour biopsy, CT staging and liver MRI, which confirms three right-sided deposits clear of the left inflow, outflow and biliary drainage.
2Obtain RAS, BRAF V600E and MMR results and discuss the same images at colorectal and specialist hepatobiliary MDTs before either team starts an irreversible treatment sequence.
3Agree systemic treatment followed by combined sigmoid resection and right hepatectomy because all disease is anatomically clearable and the left-liver remnant is adequate.
4After treatment, repeat CT and liver MRI confirm no new sites and persistent resectability; optimise nutrition, thrombosis prevention and operative fitness.
5Pathology confirms R0 removal of the sigmoid primary and all three liver metastases. Verify actual margin reports, postoperative liver function and the joint MDT’s further-treatment and surveillance plan.

02Bilobar disease considered for conversionReassess resectability after a defined systemic-treatment intervalA 55-year-old with resected colon cancer has six bilobar liver metastases, including one close to the right hepatic vein, and no disease outside the liver. The first local report calls the disease unresectable.

1Refer to a specialist hepatobiliary MDT with the diagnostic CT and dedicated liver MRI rather than using lesion count or a non-specialist report as the final decision.
2Map which deposits require resection or ablation and quantify the proposed future liver remnant; record the exact anatomical barrier to current clearance.
3Choose biomarker-informed systemic therapy with an explicit conversion aim and scheduled restaging rather than open-ended palliative labelling.
4After four cycles, MRI shows response without new disease. The MDT plans portal-vein embolisation followed by staged parenchymal-sparing resection and ablation.
5Verify remnant hypertrophy, imaging stability and pathology after each phase; if progression removes curative feasibility, record the revised non-curative intent honestly.

03Obstructing primary with synchronous metastasesControl the bowel emergency without abandoning whole-disease planningA 70-year-old with a stenosing descending-colon cancer and multiple liver lesions develops distension, faeculent vomiting, absolute constipation, pulse 120/min and lactate 3.8 mmol/L.

1Begin ABCDE resuscitation, keep nil by mouth, establish intravenous access, correct fluid and electrolyte loss, monitor urine output and provide nasogastric decompression for persistent vomiting.
2Obtain urgent contrast CT to define the transition point, perforation or ischaemia and to update metastatic burden; call colorectal surgery and anaesthesia while resuscitation continues.
3Choose stenting, diversion or resection according to left-sided anatomy, curative possibility, perforation risk and fitness; do not delay decompression for molecular results.
4After recovery, obtain tissue and RAS, BRAF V600E and MMR results and complete liver imaging so the joint MDT can set the subsequent liver and systemic-treatment plan.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Loss of resectability

New extrahepatic spread, vascular encasement or inadequate future liver remnant can remove a local curative option unless conversion or staged strategies succeed.

Primary-tumour obstruction or perforation

A synchronous primary may narrow or perforate during systemic treatment, forcing urgent diversion, stenting or resection and altering the planned sequence.

Biliary obstruction and infection

Central hepatic disease can compress bile ducts, causing jaundice and cholangitis that require urgent drainage and infection treatment before further anticancer therapy.

Post-hepatectomy liver failure

Insufficient functioning remnant produces coagulopathy, jaundice, lactate elevation and organ failure; careful volumetry and functional assessment reduce this risk.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Compare liver lesions by segment and size on the same imaging modality after each systemic-treatment phase and look actively for new extrahepatic disease.
Review blood count, renal and hepatic function, neuropathy, diarrhoea, mucositis, weight and performance status according to the chosen systemic regimen.
At every MDT reassessment, record whether disease is resectable, potentially convertible or not amenable to local treatment and state the anatomical reason.
After liver intervention, track bilirubin, INR, lactate, glucose, renal function, drain or bile-leak features and signs of sepsis, then verify every pathology margin.
During follow-up, interpret symptoms and CEA with scheduled cross-sectional imaging; investigate a rising marker rather than equating it automatically with unresectable recurrence.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Resectability is specialist judgement

Future liver remnant, distribution, vascular relationships, extrahepatic disease and response all matter.

Sequence protects options

Unplanned bowel or liver treatment can compromise later curative combinations.

Molecular testing is actionable

RAS and BRAF results affect targeted-therapy choice in metastatic disease.

Recurrence can remain treatable

Repeat liver resection or ablation may be considered after structured restaging.

11Common pitfallsFrequent interpretation and management errors.

01
Calling multiple liver lesions unresectable without hepatobiliary review can deny curative-intent treatment.
02
Starting systemic treatment before obtaining appropriate biomarkers may limit rational drug selection.
03
Focusing on liver disease while ignoring an obstructing primary can create an emergency during therapy.
04
Using CEA change alone to judge response ignores anatomical imaging and clinical status.

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