Tumor volume and tumor absorbed dose are significant predictors of the time to tumor progression in intrahepatic cholangiocarcinoma (CCA), according to a new study by Italian researchers.
According to first author Tommaso Depalo from the Regional Center of Nuclear Medicine at the University Hospital of Pisa in Italy and the coauthors of the study, knowing the radiobiological parameters can help to determine the administered activity of radioembolization and improve the outcome of treatment. Radioembolization can be used as an alternative option to treat patients with unresectable intrahepatic CCA.
Absorbed dose calculation can have an impact on the clinical outcome of the treatment. Another parameter that can affect the outcome is the variable radiosensitivity of different tumors and hepatic tissue.
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Knowing these parameters could help improve the planning of radiation therapy to achieve better clinical outcomes.
Read more about cholangiocarcinoma prognosis
In the present study, published in Scientific Reports, the researchers retrospectively calculated specific tumor radiosensitivity in a series of patients with unresectable intrahepatic CCA who underwent radioembolization. They analyzed 21 therapeutic procedures in 15 patients.
They calculated tumor absorbed doses by processing the post-therapeutic yttrium-90-positron emission tomography (PET)/computed tomography (CT) images and the pretreatment contrast-enhanced CT scans. They also calculated the α and α3D parameters using tumor absorbed dose and tumor volumes before and after treatment.
They found that the median tumor average absorbed dose was 93 Gy. Its correlation with the residual tumor mass was statistically significant. The median α and α3D parameters were 0.005 and 0.007 Gy−1, respectively.
“The knowledge of these radiobiological parameters would enable further advances in the field of personalized dosimetry for [selective internal radiation therapy], by calculating the tumor absorbed dose given the tumor specific radiosensitivity and the desired final mass of the treated lesion,” the researchers concluded.
Selective internal radiation therapy consists of an intra-arterial injection of micron-sized particles loaded with yttrium-90. Pretreatment SPECT/CT and post-treatment yttrium-90-PET/CT allow for 3-dimensional (3D) dosimetry to be performed by taking into account the 3D distribution of yttrium-90 activity within the targeted liver and tumor.
Reference
Depalo T, Traino AC, Bargellini I, et al. Assessment of radiation sensitivity of unresectable intrahepatic cholangiocarcinoma in a series of patients submitted to radioembolization with yttrium-90 resin microspheres. Sci Rep. 2021;11(1):19745. doi:10.1038/s41598-021-99219-7
