Boron neutron capture therapy for recurrent pediatric sialoblastoma: the first clinical experience and dosimetric considerations for skeletal safety with 4-year follow-up.

Sialoblastoma is a rare, aggressive pediatric salivary gland tumor often refractory to conventional therapies, which carry significant risks of growth impairment in children. We report the 52-month follow-up of a 6-year-old girl with recurrent sialoblastoma treated with two sessions of boron neutron capture therapy (BNCT). She achieved a 23-month complete response after the first session and a sustained partial response following the second. Dosimetric analysis using a conservative α/β ratio of 2.0 Gy for late-responding tissues showed that the equivalent dose in 2-Gy fractions to the mandible area was approximately 4.3 Gy-Eq. This is substantially below the 15 Gy threshold recognized for skeletal impairment. Our findings suggest that BNCT is a highly selective salvage option that effectively controls refractory pediatric tumors while preserving craniofacial development.