Intrahepatic cholangiocarcinoma (iCCA) may be hidden in patients with cancers of unknown primary origin, according to a new study published in the British Journal of Cancer.

The researchers found that 34% of a cohort of patients with cancer of unknown primary with liver involvement met the criteria for a diagnosis of iCCA.

“The diagnosis of iCCA is difficult to differentiate pathologically from other tumor types, such as pancreatic and upper gastrointestinal carcinomas, due to the lack of specific immunohistochemical biomarkers,” the authors said.

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“However, there are distinct radiological appearances that can be used for iCCA diagnosis. In this study, we sought to identify patients with clinicopathological features in keeping with iCCA from a cohort of patients provisionally diagnosed with [cancer of unknown primary].”

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The research team conducted a retrospective study on 228 patients diagnosed with a provisional diagnosis of cancer of unknown primary between 2017 and 2020. The patients were classified into “liver involvement” (72 patients) and “no liver involvement,” and after a retrospective radiological review of all of those with liver involvement, an iCCA cohort was established.

Of the 72 with liver involvement, 24 were ultimately diagnosed with iCCA. These patients were more likely to be women, to be younger, and to have a poorer Eastern Oncology Cooperative Group performance status. Given the encouraging recent clinical trial results of new multiple targeted therapies for patients with iCCA, there is an increased need to identify these patients and perform appropriate molecular testing to determine the optimal treatment approach.

In addition, recent reports indicated that up to 90% of cancer of unknown primary tumors harbor mutations that are potential treatment targets, further emphasizing the importance of molecular profiling for these patients. The authors recommend introducing a new “liver-dominant” cancer of unknown primary profile into current guidelines, to facilitate prompt identification of patients with iCCA.


Conway AM, Morris GC, Smith S, et al. Intrahepatic cholangiocarcinoma hidden within cancer of unknown primary. Br J Cancer. Published online April 28, 2022. doi:10.1038/s41416-022-01824-4