Proton therapy and/or helical tomotherapy for locally advanced sinonasal skull base adenoid cystic carcinoma: Focus on experience of the Institut Curie and review of literature

Abstract

Background: Sinonasal adenoid cystic carcinomas (SNACC) have high propensity for skull base (SB) infiltration. Unresectability or incomplete surgical resection in such cases make radiotherapy treatment paramount. Curative dose escalation is challenging because of adjacent organs at risk, especially in locally advanced cases.Methods: Eighteen patients that had locally advanced SB SNACC with unresectable or incomplete surgical resection treated by proton therapy and/or helical tomotherapy at Institut Curie between 3/2010 and 8/2020 were retrospectively included. Results: After median follow-up of 52 months, 5-year OS, LRRFS, DMFS, DFS rates were, respectively, 47% (95%CI: 26-83), 50% (95%CI: 36-88), 39% (95%CI: 26-81), 33% (95%CI: 22-73). One patient had grade 4 late optic nerve disorder.Eight patients had grade 3 late toxicity including mainly hearing impairments. Conclusion:Proton therapy and helical tomotherapy are effective and safe methods for curative dose escalation of locally advanced SB SNACC, which are a poor prognosis subgroup. Available literature suggests carbon-ion therapy could be an efficient alternative.

Long-Term Outcomes Following Definitive or Adjuvant Proton Radiotherapy for Adenoid Cystic Carcinoma

“…Our current practice is to give concurrent chemotherapy for those with gross residual disease, which is supported in other modern series. 19 , 20 This finding was supportive for chemotherapy for advanced-stage ACC and highlights that this population tends to have a poor prognosis even with the addition of concurrent systemic therapy compared to those in which a gross total resection is achieved.…”