Planned fractionated boron neutron capture therapy using epithermal neutrons for a patient with recurrent squamous cell carcinoma in the temporal bone: a case report.

Background: We describe the first case of extensive squamous cell carcinoma in the temporal bone recurring after surgery, conventional radiotherapy, and chemotherapy, which was treated using planned fractionated boron neutron capture therapy (BNCT).
Methods: A 42-year-old patient received BNCT twice with a 1-month interval to ensure neutron capture in the deep lesion. We used an epithermal neutron beam as the neutron source and boronophenylalanine as the boron compound. The total radiation doses in the tumor beneath the skin, at the deepest point of the tumor, and in the skin around the right auricle were estimated as 41.8, 36.9, and 15.8 Gy-Eq, respectively.
Results: Radiological studies performed 6 months after the first BNCT showed obvious tumor shrinkage and no evidence of residual tumor.
Conclusion: We believe that planned fractionated BNCT is an effective treatment option for patients with inoperative extended carcinomas in the temporal bone.