Liver anatomy and modern treatment options for secondary (metastatic) liver cancer

This update explains surgical anatomy (Couinaud segments), liver function and regenerative capacity, why the liver commonly hosts metastases, and modern options to treat secondary liver cancer: parenchymal-sparing resections, PVE, systemic chemotherapy, RFA/MWA, Y-90 radioembolization, and staged procedures. Outcomes are best in high-volume hepatobiliary centers, so early multidisciplinary referral matters.

Overview and anatomy

The liver is the body's largest internal organ. It sits under the right lower ribs in the right upper abdomen and spans toward the midline. About a quarter of the body's blood volume passes through the liver each minute, supplied arterially by the hepatic artery and venously by the portal vein (which carries nutrient-rich blood from the gut).

Functionally the liver is divided into right and left hemi-livers along the principal plane (Rex-Cantlie line). The Couinaud segmental system remains the surgical standard: eight segments (I-VIII), with the caudate lobe labeled segment I. Each segment has its own inflow (portal triad: portal vein, hepatic artery, bile duct) and can, in many cases, be resected independently.

Major hepatic veins (right, middle, left) run in the main fissures and drain sections of the liver to the inferior vena cava. Smaller accessory veins may also drain directly to the cava and are important to identify during surgery.

Key functions and regenerative capacity

The liver metabolizes nutrients, drugs, and toxins; synthesizes proteins and clotting factors; recycles red blood cells; and produces bile to aid fat digestion. The organ has a large functional reserve and substantial regenerative ability. In clinical practice it is generally possible to resect a large portion of liver tissue (commonly up to two thirds or more in selected patients) provided adequate remnant liver volume and function remain.

Why the liver is a common site for metastases

Venous drainage from the bowel flows to the liver via the portal vein. Cancer cells from colorectal and other gastrointestinal tumors commonly seed the liver and can grow as secondary (metastatic) tumours. Careful understanding of anatomy guides safe resection of these metastases.

Modern surgical and interventional treatments

Surgical resection remains the standard of care for resectable colorectal liver metastases and can offer long-term survival for well-selected patients. High-volume centers report low perioperative mortality and acceptable complication rates when resections are performed by experienced hepatobiliary teams.

Techniques that improve safety and expand resectability include:

• Parenchymal-sparing and segmental resections using devices such as the Cavitron Ultrasonic Surgical Aspirator (CUSA), energy devices, and stapling tools.

• Preoperative portal vein embolization (PVE) to induce hypertrophy of the future liver remnant over several weeks when planned resections would leave too little liver.

• Systemic chemotherapy (neoadjuvant and perioperative) to downstage disease and improve outcomes.

• Locoregional therapies: radiofrequency ablation (RFA) and microwave ablation (MWA) for small tumours; transarterial radioembolization (Yttrium-90) for selected patients; cryoablation is now used less commonly.

• Specialized staged procedures (for example, ALPPS) in highly selected cases, with careful consideration of risks and benefits.

Outcomes and referral

Five-year survival after curative liver resection for colorectal metastases depends on patient selection and adjunctive therapy; many contemporary series report substantial long-term survival in properly selected patients. Because outcomes are better in experienced centers, early referral to a hepatobiliary multidisciplinary team is important for patients with potentially resectable liver metastases.