Liver resection is a surgical procedure that involves removing a diseased or damaged portion of the liver, most commonly performed to remove tumors. The question of how many times this can be done does not have a simple numerical answer. The feasibility of a repeat resection is determined not by the count of previous surgeries, but by the volume and quality of the remaining healthy liver tissue. Surgeons focus on ensuring that enough functional liver remains after the procedure to prevent the life-threatening complication of liver failure.
Understanding Liver Regeneration
The liver is unique among solid organs due to its remarkable capacity for regeneration. Following the surgical removal of a portion of the organ, the remaining liver tissue begins a complex biological process to restore the original mass and function. This regenerative response is not the growth of new liver segments, but rather the compensatory enlargement of the existing, healthy tissue.
The process is initiated by changes in blood flow and the release of signaling molecules, including growth factors like Hepatocyte Growth Factor (HGF). Hepatocytes, the main functional cells, respond by entering the cell cycle, leading to rapid cell division (hyperplasia). This cell multiplication, combined with the enlargement of individual cells (hypertrophy), allows the liver to restore its functional mass.
The regenerative process is tightly regulated, ensuring that the liver stops growing once a sufficient mass relative to the body’s needs is achieved. This capacity for regrowth is the foundational reason why a patient may safely undergo multiple, sequential resections over time. The success of any subsequent surgery depends on the complete and functional recovery of the remnant liver from the previous operation.
The Critical Limit: Future Liver Remnant (FLR)
For every liver resection, the primary concern is preventing Post-Hepatectomy Liver Failure (PHLF), which is directly related to the size of the liver tissue left behind. This remaining functional part is known as the Future Liver Remnant, or FLR. Surgeons use advanced imaging techniques, such as CT or MRI, to accurately calculate the volume of the FLR before the operation.
The FLR is typically standardized by calculating its volume as a percentage of the patient’s estimated total liver volume, which is often derived from body surface area. This calculation provides an individualized metric for assessing surgical safety. The minimum percentage of FLR required varies significantly based on the health and functional quality of the tissue.
For a patient with an entirely healthy liver, a standardized FLR of at least 20% is considered sufficient to tolerate a major resection safely. However, this threshold increases markedly for patients with underlying liver disease or those who have undergone prior treatments that compromise liver health.
When the liver is compromised, a larger volume of tissue must be preserved to ensure adequate function post-surgery. For example, patients with steatosis (fatty liver disease) or extensive prior chemotherapy generally require the FLR to be raised to at least 30%. Patients with cirrhosis, characterized by significant scarring, require an even larger remnant, often set at 40% or more to mitigate the high risk of PHLF. This necessity for a larger FLR limits the extent of tissue removal and the possibility of repeat resections.
Underlying Factors Affecting Resection Safety
The functional quality of the liver tissue is as important as its physical volume in determining the safety of a resection. Underlying liver diseases severely compromise the ability of the remnant liver to regenerate effectively. Cirrhosis, for instance, replaces healthy, functional liver cells with scar tissue, significantly impairing the organ’s overall reserve and regenerative capacity.
Steatosis, or the accumulation of fat within the liver cells, is a known risk factor for complications following liver surgery. A fatty liver is more fragile and prone to injury and its cells are less capable of proliferating post-operatively. This condition, which may be caused by metabolic issues or specific chemotherapies, necessitates a more conservative surgical approach and a larger FLR.
Prior systemic chemotherapy, a common treatment for liver metastases, can induce damage to the liver cells, known as chemotherapy-associated steatohepatitis. Chemotherapy, particularly regimens containing oxaliplatin or irinotecan, can reduce the liver’s ability to regenerate and increase the risk of Post-Hepatectomy Liver Failure. For patients who have received long courses of chemotherapy, the surgical team must anticipate this reduced reserve and demand a higher FLR percentage for a safe operation.
Techniques to Increase Resectability
When the FLR is predicted to be below the safe threshold, surgeons can employ specialized techniques to intentionally increase the volume of the healthy future remnant before the main operation. These strategies are designed to induce hypertrophy in the lobe that will remain, thereby converting an initially unresectable tumor into a resectable one. This allows a greater number of patients to safely undergo curative surgery.
Portal Vein Embolization (PVE) is a minimally invasive technique where the blood supply to the part of the liver containing the tumor is blocked. This redirection of portal blood flow stimulates the healthy lobe to rapidly grow, or hypertrophy, over several weeks. PVE is a standard method used to boost the FLR and increase the safety margin for major resections.
Another, more aggressive staged surgical approach is Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy (ALPPS). This procedure involves two stages: first, the ligation of the portal vein and the physical division of the liver parenchyma. This dual manipulation induces an extremely rapid and substantial increase in the FLR volume, often within one to two weeks, though this technique carries a higher risk of complications.