Proton Therapy for Advanced Juvenile Nasopharyngeal Angiofibroma

Abstract

Purpose: To provide the first report on proton radiotherapy (PRT) in the management of advanced nasopharyngeal angiofibroma (JNA) and evaluate potential benefits compared to conformal photon therapy (XRT). Methods: We retrospectively reviewed 10 consecutive patients undergoing PRT for advanced JNA in a definitive or postoperative setting with a relative biological effectiveness weighted dose of 45 Gy in 25 fractions between 2012 and 2022 at the Heidelberg Ion Beam Therapy Center. Furthermore, dosimetric comparisons and risk estimations for short- and long-term radiation-induced complications between PRT plans and helical XRT plans were conducted. Results: PRT was well tolerated, with only low-grade acute toxicities (CTCAE I–II) being reported. The local control rate was 100% after a median follow-up of 27.0 (interquartile range 13.3–58.0) months. PRT resulted in considerable tumor shrinkage, leading to complete remission in five patients and bearing the potential to provide partial or complete symptom relief. Favorable dosimetric outcomes in critical brain substructures by the use of PRT translated into reduced estimated risks for neurocognitive impairment and radiation-induced CNS malignancies compared to XRT. Conclusions: PRT is an effective treatment option for advanced JNA with minimal acute morbidity and the potential for reduced radiation-induced long-term complications.

Helium Ion Therapy for Advanced Juvenile Nasopharyngeal Angiofibroma

“…Dosimetric advantages and subsequent reductions in NTCP were observed across all OAR, with the extent of the individual reductions depending on their proximity to the target volume. The relative differences in dose distribution between the two modalities were generally notable, while the absolute differences may appear relatively small for most OAR since PRT already presents a high degree of conformality [ 8 ] and the dose prescription of 45 Gy (RBE) is relatively low.…”

“…By performing risk assessments for radiation-induced secondary CNS malignancies, we found a mean relative risk of 1.4 for PRT over HRT. Taking into account our preliminary investigation comparing PRT and photon radiotherapy within the same cohort, the latter exhibits a relative risk of 2.95 compared to HRT [ 8 ]. However, the applied risk assessment model does not account for risks such as the induction of meningioma or the carcinogenic impact of secondary neutrons.…”

“…Delineation of the clinical target volume (CTV) and organs at risk (OAR) was performed according to the authors’ institutional guidelines, as previously reported [ 8 ]. Additional cerebral substructures were contoured for further evaluation of potential radiation-induced implications on neurocognitive functions according to previously published guidelines and landmarks [ 15 , 16 ].…”

“…The treatment plans were designed using two to four treatment beams, either for delivery at the isocentric gantry or the fixed beamline, depending on the positioning between OAR and target volumes. All proton plans were delivered for patient treatment as reported in Hoeltgen et al [ 8 ]. Treatment characteristics are summarized in Table 1 .…”

“…The first clinical report on proton radiotherapy (PRT) for advanced JNA has shown excellent local control and patient outcomes, with potentially reduced radiation-induced long-term complications compared to conventional radiotherapy [ 8 ]. The use of carbon ions in younger patients remains disputed.…”