Living donor liver transplantation in transplant oncology: A disease-specific framework for access, timing, and donor risk

Living donor liver transplantation (LDLT) should not only be evaluated as an alternative graft source in transplant oncology; it should also be evaluated as a disease-specific intervention on access and oncologic time. By removing dependence on deceased-donor availability, LDLT can convert an uncertain wait into a planned operation-but that temporal advantage is not biologically neutral, and its consequences differ sharply by tumor type. In hepatocellular carcinoma, an abbreviated wait can reduce waitlist dropout but may also shorten the interval during which aggressive biology would otherwise declare itself; contemporary biology-based selection has reduced this concern in selected cohorts. In perihilar cholangiocarcinoma, LDLT solves organ scarcity, but the neoadjuvant and staging protocol-not the graft-must remain the actual selection mechanism, and irradiated recipient anatomy adds a distinct technical burden. In intrahepatic cholangiocarcinoma, LDLT remains investigational, justified only by durable response to systemic therapy in small, prospectively protocolized cohorts. In neuroendocrine liver metastases, direct living-donor evidence is too sparse to support a confident recommendation in either direction. In colorectal liver metastases, LDLT can be framed as a timing technology: transplantation is scheduled once sustained chemotherapy response suggests a temporarily favorable biological state, on the premise that an unpredictable wait might otherwise close that window. This narrative review deliberately isolates the living-donor evidence within each of these five diseases rather than treating LDLT as one intervention, and proposes a common framework-the oncologic clock, the strength of pre-transplant biological selection, and the donor risk that expected recipient benefit can justify-for interpreting it. We further argue that transplant benefit over the best nontransplant alternative, rather than post-transplant survival, should anchor these judgments; that left-lobe and two-stage (RAPID-type) grafting strategies offer a means to reduce donor risk; and that the appropriate metrics depend on whether LDLT operates within a deceased-donor-predominant or a living-donor-predominant health-care system. Across all five diseases, graft source itself appears to matter less than who is selected and when; the central task for the next generation of studies is to report outcomes from evaluation and donor exposure forward, not from transplantation alone.