ESTRO 2024 - Abstract Book

S1290

Clinical - Head & neck

ESTRO 2024

Keywords: Adaptive RT, Synthetic-CT, Dose calculation

1413

Digital Poster

Can NRAS mutation status predict outcome in head and neck mucosal melanoma treated with carbon ions?

Sara Ronchi, Giulia Fontana, Maria Bonora, Rossana Ingargiola, Anna Maria Camarda, Sara Lillo, Eleonora Rossi, Stefania Russo, Barbara VIschioni, Ester Orlandi

National Center for Oncological Hadrontherapy (CNAO), Clinical Department, Pavia, Italy

Purpose/Objective:

Purpose of this study was to evaluate the impact of NRAS mutational status on oncological outcome in head and neck mucosal melanoma (HNMM) patients treated with carbon ion radiotherapy (CIRT).

Material/Methods:

Patients treated with CIRT after surgery or biopsy only for non-metastatic HNMM and available genetic profile information about NRAS gene were considered in the analysis. Data about oncological outcomes were prospectively collected and then retrospectively analyzed. Local Progression Free Survival (LPFS), Progression Free Survival (PFS), Distant Progression Free Survival (DPFS) and Overall Survival (OS) rates were calculated according to the Kaplan Meier Method. The impact of NRAS mutation was evaluated with Log-rank test and individually adjusted for the most relevant factors (surgery pre-CIRT, immunotherapy after CIRT, tumor status and tumor stage) with Cox regression model (α=0.05).

Results:

From June 2013 to September 2022, 56 consecutive patients received CIRT for HNMM at our institution. Information about NRAS genetic profile was available for 25 patients (44.6%). Among these 25 patients, 13 (52%) were male, 10 (48%) female; median age was 68 years (range 42 – 87 years). Primary tumor location was nasal cavity and paranasal sinuses in 23 and 2 patients, respectively. Tumor stage was T3 in 11 patients (44%) and T4 in 14 patients (56%). Tumor status was naïve and recurrent in 14 (56%) and 11 (44%) cases, respectively. Eighteen (72%) and 7 (28%) patients received surgery before CIRT or exclusive CIRT with radical intent, respectively. Among operated patients, macroscopic disease at pre-CIRT MRI was found in 15 cases (83.3%). In patients with macroscopic disease prior to CIRT (15 patients after surgery and 7 patients after biopsy only), median GTV was 80 cc (range 0.1 – 302.9 cc). Thirteen patients (52%) had NRAS gene mutation, 12 (48%) were NRAS-wild type. CIRT was delivered with a prescription dose ranging from 64 to 68.8 Gy(RBE) in 16 fractions, 4 fractions per week. Eighteen patients (72%) received immunotherapy after CIRT, mainly for distant progression during follow-up. After a median follow-up of 22.2 months, 2 year- LPFS, DPFS, PFS and OS rates were 79.5%, 36.2%, 21.8% and 84.7%, respectively (Kaplan- Meyer curves are shown in Figure 1).