ESTRO 2023 - Abstract Book

S942

Digital Posters

ESTRO 2023

.

Conclusion SABR in the management of oligometastatic and recurrent head and neck cancer provides a favorable local control and provide a chance to delay systemic therapy with favorable overall survival outcomes for this well-selected subset of patients.

PO-1178 Elective node irradiation and perineural invasion in salivary gland tumors: the MedAustron approach

A. Nachankar 1,3 , E. Hug 1 , P. Georg 1 , M. Pelak 1 , S. Tubin 1 , J. Gora 2 , A. Fraller 1 , P. Mozes 1 , P. Fossati 1,4

1 MedAustron Ion Therapy Center, Austria, Radiation Oncology, Wiener Neustadt, Austria; 2 MedAustron Ion Therapy Center, Austria, Medical Physics, Wiener Neustadt, Austria; 3 ACMIT Gmbh, Austria, Research and Development in Medical Technology, Wiener Neustadt, Austria; 4 Karl Landsteiner University of Health Sciences, Austria, Radiation Oncology, Krems an der Donau, Austria Purpose or Objective Purpose: Salivary gland cancers (SGCs) are uncommon malignancies with unique biology and natural course. In non resectable cases outcomes with photons-based RT or RT-CHT remain suboptimal as compared to squamous cell carcinoma. Carbon ions have shown promising results in non-resected SGCs in German and Japanese studies. In the German experience elective nodal irradiation (ENI) was routinely used in clinically node negative (cN0) SGCs, however Japanese centers never performed ENI and isolated neck recurrence were rare in their series. There is no consensus on need of ENI in SGCs. Perineural invasion (PNI) is at least as important as lymphatic spread in SGC. Risk of lymph node involvement and PNI in SGCs is highly variable across histologies, primary site and T stage. Here we propose recommendations for clinical target volume (CTV) with respect to ENI and PNI in cN0 SGCs. Materials and Methods Material/Methods: We stratified cN0, SGCs as per T stage, primary site and histologies. For ENI Tumor locations were classified into, very low risk, low risk, mid-high risk unilateral and mid-high risk bilateral groups for lymphatic spread (figure 1). SGC histologies were divided into highly lymphotropic- high and intermediate grade mucoepidermoid carcinoma, adenocarcinoma NOS and low lymphotropic- Adenoid-cystic carcinoma (ACC), salivary duct carcinoma, acinic-cell carcinoma, low grade mucoepidermoid carcinoma, papillary adenocarcinoma (figure 1). For PNI, tumors were grouped into cranial and caudal primary site (figure 1, 2) and ACC were classified as neurotropic and non-ACC as non-neurotropic histologies. Twenty-three patients with SGCs treated with CIRT +/- proton therapy at MedAustron from July 2019 to September 2022 were analysed. Prescription dose CIRT (n =20) was 57 .6 - 70.5 Gy [RBE]/12 -22 fractions, with 4-5 fractions/ week. Three patients received proton therapy 50-54 Gy [RBE]/ 25-27 fractions followed by CIRT boost 12- 20 Gy [RBE]/4-5 fractions, with 4-5 fractions/ week.