Comparison of the Biological Response of a Head and Neck Carcinoma and a Glioblastoma Cell Line Under Neutron Irradiation with BPA Administration

Background and objective: In Boron Neutron Capture Therapy, treatment planning is based on a weighted dose in which dose components are weighted with different biological effectiveness (RBE) factors. The most important one for the tumor dose is the compound dependent biological effectiveness (CBE) factor which weighs the boron dose. This was established for brain tumors from radiobiological experiments and has been extrapolated to the more recent application of BNCT to head and neck cancers. The purpose of this work is to study the validity of this assumption. Methods: Two cell lines, CAL-33 (head and neck squamous cell carcinoma) and A172 (Glioblastoma Multiforme), were irradiated with a very pure thermal-equivalent neutron beam after BPA incubation, and the surviving fraction of cells after irradiation was determined by clonogenicity assays. Results: The Compound Biological Effectiveness of both cell lines is similar, although for head and neck carcinoma, 10% higher values are systematically found. In addition to this, radiobiological coefficients for the different dose components (photon, neutron and boron) of BNCT in both cell lines are provided.