Preliminary evaluation of mucosal melanoma of the head and neck with carbon ion radiotherapy
PO-1200
Abstract
Preliminary evaluation of mucosal melanoma of the head and neck with carbon ion radiotherapy
Authors: Azusa Hasegawa1, Teruki Teshima1, Osamu Suzuki1, Makoto Anzai1, Hirofumi Uchida1, Jiro Fujimoto1, Takashi Fujii2
1Osaka Heavy Ion Therapy Center, Radiation therapy, Osaka, Japan; 2Osaka International Cancer Institute, Head and Neck Surgery, Osaka, Japan
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Purpose or Objective
This report aims to evaluate preliminary results of carbon ion radiotherapy (CIRT) in patients (pts) with mucosal melanoma of the head and neck (MMHN).
Material and Methods
Between October 2018 and April 2022, a total of 41 pts with MMHN were treated with CIRT. None of these patients had either regional lymph node or distant metastasis before CIRT and had previous history of radiotherapy for same lesion. The prescribed tumor doses were 57.6 or 64.0 Gy (RBE) in 16 fractions over 4 weeks. Twenty-seven of 41 pts (66%) received immune checkpoint inhibitors (ICIs) to prevent metastases after CIRT. Local response within 6 months and toxicity were respectively evaluated using RECIST and CTCAE v.4.0 criteria. Local control (LC), overall survival (OS), and progression-free survival (PFS) rates were determined using the Kaplan-Meier method. All survival times were calculated from the first day of CIRT.
Results
The patients consisted of 15 males and 26 females aged from 37 to 92 years with a median age of 76 years. Tumor site was nasal and/or paranasal sinus in 40 cases and oral cavity in one. Thirty-five pts (85%) were irradiated with 64.0 Gy (RBE) and 6 pts (15%) were with 57.6 Gy (RBE). Median follow-up period was 15.3 months (range, 2.0-42.6 months). Tumor response using RECIST was complete response (CR) for 16 pts (39%), partial response (PR) for 18 pts (44%) and stable disease (SD) for 7 pts (17%), with the effective rate (CR + PR) being 83%. The 1-year and 2-year LC rates were 92.3% (95% confidence interval [CI] 72.5%-98.0%), respectively. In-field recurrence was observed in 3 pts. LC period from the start of CIRT to recurrence in these pts was 10.6, 11.5, and 32.1 months, respectively. None of these pts received ICIs after CIRT. The 1- and 2-year PFS rates were 59.5% (95% CI 42.4%-73.0%) and 20.8% (95% CI 4.5%-45.1%), respectively. Of 23 pts (56%) who developed recurrence, the initial recurrence pattern was distant metastasis in 12 pts, regional recurrence in 7, regional plus distant metastases in 2, local recurrence in one, and local plus regional recurrence in one. The 1- and 2-year OS rates were 84.4% (95% CI 68.4%-92.7%) and 53.4% (95% CI 25.3%-75.0%), respectively. The median PFS and OS were 16.4 and 28.4 months. The 2-year OS rates of CIRT with and without ICIs were 88.2% (95% CI 67.5%-96.1%) and 24.1% (95% CI 4.0%-53.2%), respectively. Mucositis during/at the end of treatment was G1 and G2 for 16 pts (39%) and 25 pts (61%), respectively. No G2 or higher acute mucositis and dermatitis within 3 months was observed. G3 or higher late toxicities were observed in 2 patients (5%). One patient developed ipsilateral blindness (G4), and one developed G3 visual impairment.
Conclusion
Our preliminary data of CIRT has shown acceptable toxicities and excellent local control for MMHN. However, a larger series of patients and a longer follow-up are needed to better investigate outcomes.