Management of rare primary liver cancers: combined hepato-cholangiocarcinoma and fibrolamellar hepatocellular carcinoma.

Fibrolamellar hepatocellular carcinoma (FLC) and combined hepatocellular-cholangiocarcinoma (cHCC-CCA) are rare primary liver cancers for which limited evidence is available to guide clinical management. cHCC-CCA could arises in the context of chronic liver disease and shares epidemiological and molecular features with both hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA), reflecting its intermediate biological and clinical position between these two entities. Its diagnosis remains challenging particularly when based on tumor biopsy specimens. Surgical resection remains the standard of care when feasible. Liver transplantation, trans-arterial chemoembolization, ablation, or selective internal radiation therapy have been used in selected cases. For advanced disease, systemic treatments commonly used for HCC or CCA have been applied in real-world practice, including platinum-based chemotherapy, tyrosine kinase inhibitors, and more recently immunotherapy. In addition, molecularly guided therapies have been explored, as targetable genetic alterations can be identified in a subset of cHCC-CCA. In contrast, FLC typically arises in non-cirrhotic livers of young patients and is frequently associated with metastatic disease, including lymph node involvement. At the molecular level, FLC is characterized by the presence of the DNAJB1-PRKACA fusion and by elevated serum procalcitonin secreted by the tumor. Surgical resection remains the cornerstone of treatment when feasible, but data guiding systemic therapy in unresectable cases are limited. Several regimens, including gemcitabine-oxaliplatin, lenvatinib, and immunotherapy, have been evaluated. More recently, clinical trials have reported antitumor activity with combinations of immunotherapy and vaccines targeting the DNAJB1-PRKACA fusion. To improve patient care, since cHCC-CCA and FLC are rare subtypes of liver cancer, we need to compile prospective samples and clinical data from the patients, including their response to any type of treatment at the national and international levels.