Intrahepatic cholangiocarcinoma, often abbreviated ICC, is a primary malignancy of the liver that originates from the epithelial cells lining the intrahepatic bile ducts. It is the second most common primary hepatic malignancy, trailing only hepatocellular carcinoma, and its incidence has been rising in many parts of the world over recent decades. The clinical stakes of distinguishing ICC from hepatocellular carcinoma are considerable. Hepatocellular carcinoma, particularly when diagnosed early, can often be managed with established protocols ranging from ablation and resection to liver transplantation and, more recently, immunotherapy-based systemic regimens. Intrahepatic cholangiocarcinoma, by contrast, typically demands aggressive surgical resection with careful attention to lymph node status and biliary anatomy, and its response to treatments designed for hepatocellular carcinoma is generally poorer. When a liver mass cannot be definitively characterized before surgery, the surgical team may be forced to plan for both possibilities, and misclassification can lead to suboptimal operative strategy and delayed access to the most appropriate therapy.

Conventional tumor markers offer only partial help. Carbohydrate antigen 19-9, commonly known as CA19-9, and carcinoembryonic antigen, or CEA, are the most widely used serological markers in biliary tract malignancies, but neither is specific enough to reliably separate intrahepatic cholangiocarcinoma from hepatocellular carcinoma, particularly in patients who also have chronic hepatitis or cirrhosis, conditions in which these markers can be elevated for reasons unrelated to cancer. Imaging, too, has its limits; small tumors, atypical enhancement patterns, and underlying liver disease can all blur the radiological distinction. This diagnostic gray zone is precisely where the new study positions itself, asking whether the lipid composition of blood plasma might carry a signature specific enough to resolve what imaging and protein markers cannot.

The research team, led by Anrui Mao and Jie Yang, with corresponding authors Kun Tong and Hongkun Zhou, drew on clinical expertise from the Department of Hepatobiliary and Pancreatic Surgery at the First Hospital of Jiaxing and collaboration with Zhejiang Chinese Medical University. The investigators assembled three groups of participants: fifty healthy normal controls, fifty patients with hepatocellular carcinoma, and thirty patients with intrahepatic cholangiocarcinoma. Plasma samples were collected from each participant and subjected to untargeted lipidomic analysis, a technique that does not presuppose which lipids might be relevant but instead surveys the entire lipid complement of a sample in an unbiased fashion. This approach is powerful precisely because it allows the data to reveal which molecular species separate the groups, rather than testing a preselected hypothesis about a single candidate molecule.

The technology underlying this survey is liquid chromatography coupled to mass spectrometry, a workhorse of modern metabolomics. In essence, the lipid extracts from each plasma sample are separated on a chromatographic column according to their chemical properties and then ionized and weighed with extraordinary precision by the mass spectrometer. Each lipid species produces a characteristic retention time and mass-to-charge ratio, and with the aid of spectral databases, these features can be assigned to specific molecular identities, including the class of lipid, the total number of carbon atoms in its fatty acyl chains, the number of double bonds, and additional structural features such as oxygen substitutions. The resulting dataset, containing thousands of features per sample, is then interrogated with statistical tools to find species whose abundance differs significantly between diagnostic groups. It is a molecular census of the blood, conducted at a level of detail that was simply unattainable a generation ago.

What the census revealed was striking in its internal logic. When the researchers compared patients with intrahepatic cholangiocarcinoma to healthy controls, the lipid species that changed most prominently belonged to three classes: phosphatidylethanolamine, sphingomyelin, and ceramide. These are not random molecules. Phosphatidylethanolamine and sphingomyelin are major structural phospholipids of cellular membranes, and ceramide sits at the hub of sphingolipid metabolism, a pathway intimately involved in cell death, proliferation, and stress responses. Cancer cells are known to remodel their membrane lipid composition extensively to support rapid growth, altered signaling, and survival under hypoxic and nutrient-poor conditions. The fact that the cholangiocarcinoma signature concentrated in the sphingolipid pathway suggests that bile duct-derived tumors may rewire lipid metabolism in a fundamentally different way than hepatocyte-derived tumors do.

That difference became even clearer when the hepatocellular carcinoma group was examined. Patients with this tumor type showed their most prominent lipid alterations in a different trio of classes: phosphatidylcholine, triglycerides, and acylcarnitines. Phosphatidylcholine is the counterpart membrane phospholipid to phosphatidylethanolamine, while triglycerides and acylcarnitines reflect fatty acid storage and mitochondrial fatty acid transport, respectively. Hepatocellular carcinoma arises from hepatocytes, the liver’s metabolic workhorses, and its lipid perturbations appear to echo the metabolic identity of the cell of origin. In other words, the two tumors leave distinct lipidological calling cards in the plasma, and the divergence is not merely a matter of degree but of pathway.

At the center of the study stands one molecule. Sphingomyelin (30:1; O2) was significantly upregulated in the plasma of patients with intrahepatic cholangiocarcinoma relative to healthy controls, but significantly downregulated in patients with hepatocellular carcinoma, with both differences reaching statistical significance at P less than 0.05. This bidirectional behavior is what gives the molecule its diagnostic power: it does not simply flag the presence of disease, it points toward one disease and away from the other. The nomenclature itself encodes the molecule’s structure, with 30:1 indicating thirty carbon atoms and one double bond across its acyl chains, and O2 denoting two additional oxygen atoms, features that define a specific and measurable molecular entity rather than a vague class of compounds.

The quantitative performance of this single lipid was remarkable. When the researchers constructed receiver operating characteristic analyses to test how well SM (30:1; O2) discriminated intrahepatic cholangiocarcinoma from the other groups, it achieved an area under the curve of 0.8793 with P less than 0.001, a level of diagnostic accuracy that exceeded the conventional markers CA19-9 and CEA in the same comparison. An area under the curve approaching 0.88 indicates substantially better-than-chance discrimination, and the fact that a single lipid species outperformed established protein biomarkers underscores the untapped diagnostic information carried in the plasma lipidome. Perhaps even more intriguingly, correlation analysis revealed that circulating levels of SM (30:1; O2) were strongly and significantly positively correlated with the TNM stage of intrahepatic cholangiocarcinoma, with a Spearman correlation coefficient of 0.721 and P less than 0.001. A correlation of that magnitude suggests that the lipid is not merely a passive bystander but tracks closely with tumor burden and progression, raising the possibility that it could eventually contribute not only to diagnosis but also to staging and monitoring.

The authors conclude that SM (30:1; O2) is a promising biomarker for intrahepatic cholangiocarcinoma, capable of effectively distinguishing it from hepatocellular carcinoma and providing valuable guidance for preoperative diagnosis and therapeutic decision-making. The study, which was approved by the Ethics Committee of the First Hospital of Jiaxing and conducted in accordance with the Declaration of Helsinki, was supported by the Key Medical Discipline of Jiaxing City in the hepatopancreatobiliary direction, the National Oncology Clinical Key Speciality, and the Zhejiang Provincial Medical and Health Science and Technology Projects. As with any biomarker discovery study, the findings will need validation in larger, independent, and multi-center cohorts before a sphingomyelin assay could enter routine clinical practice, and questions about how the lipid behaves in other liver diseases, such as cirrhosis, cholangitis, and steatohepatitis, will need careful answers. But the conceptual advance is clear and consequential: the metabolic identity of a liver tumor, written in the language of lipids, can be read from a simple blood draw. If subsequent studies confirm the performance of SM (30:1; O2), surgeons could one day walk into the operating room knowing, before the first incision, which cancer they are about to face, and patients could receive the right operation, the right therapy, and the right prognosis far earlier in their disease course.

Subject of Research: Lipidomic identification of sphingomyelin (30:1; O2) as a plasma diagnostic biomarker for intrahepatic cholangiocarcinoma

Article Title: Sphingomyelin (30:1; O2) as a novel lipid biomarker associated with the diagnosis of intrahepatic cholangiocarcinoma

Article References: Mao, A., Yang, J., Bian, C., Jia, Y., Tong, K., & Zhou, H. (2026). Sphingomyelin (30:1; O2) as a novel lipid biomarker associated with the diagnosis of intrahepatic cholangiocarcinoma. BMC Cancer. https://doi.org/10.1186/s12885-026-17142-4

Image Credits: AI Generated

DOI: 10.1186/s12885-026-17142-4

Keywords: intrahepatic cholangiocarcinoma, hepatocellular carcinoma, sphingomyelin, lipidomics, biomarker, liquid chromatography-mass spectrometry, CA19-9, CEA, liver cancer, sphingolipids, TNM stage, plasma diagnostics