Spot Scanning Proton Therapy for Sinonasal Malignant Tumors

Koichiro Nakajima; Hiromitsu Iwata; Yukiko Hattori; Kento Nomura; Shingo Hashimoto; Toshiyuki Toshito; Kensuke Hayashi; Yo Kuroda; Hideo Fukano; Hiroyuki Ogino; Yuta Shibamoto

doi:10.14338/IJPT-D-20-00043.1

Spot Scanning Proton Therapy for Sinonasal Malignant Tumors

Int J Part Ther. 2021 Jun 25;8(1):189-199. doi: 10.14338/IJPT-D-20-00043.1. eCollection 2021 Summer.

Authors

Koichiro Nakajima^{1

2}, Hiromitsu Iwata^{1

2}, Yukiko Hattori¹, Kento Nomura^{1

2}, Shingo Hashimoto², Toshiyuki Toshito³, Kensuke Hayashi⁴, Yo Kuroda⁵, Hideo Fukano⁶, Hiroyuki Ogino^{1

2}, Yuta Shibamoto²

Affiliations

¹ Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan.
² Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
³ Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya, Japan.
⁴ Department of Proton Therapy Technology, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan.
⁵ Department of Otorhinolaryngology, Nagoya City West Medical Center, Nagoya, Japan.
⁶ Department of Oral and Maxillofacial Surgery, Nagoya City West Medical Center, Nagoya, Japan.

Abstract

Purpose: Treatment of sinonasal malignant tumors is challenging, and evidence to establish a standard treatment is limited. Our objective was to evaluate the efficacy and safety of spot scanning proton therapy (SSPT) for sinonasal malignant tumors.

Patients and methods: We retrospectively analyzed patients with sinonasal malignant tumors (T1-4bN0-2M0) who underwent SSPT between May 2014 and September 2019. The prescription dose was typically either 60 GyRBE in 15 fractions or 60.8 GyRBE in 16 fractions for mucosal melanoma and 70.2 GyRBE in 26 fractions for other histologic subtypes. Endpoints included local control (LC), progression-free survival, overall survival (OS), and incidence of toxicity. Prognostic factors were analyzed using the Kaplan-Meier method and log-rank test.

Results: Of 62 enrolled patients, the common histologic subtypes were mucosal melanoma (35%), squamous cell carcinoma (27%), adenoid cystic carcinoma (16%), and olfactory neuroblastoma (10%). Locally advanced stages were common (T3 in 42% and T4 in 53%). Treatment-naïve tumors and postsurgical recurrent tumors accounted for 73% and 27%, respectively. No patient had previous radiotherapy. The median follow-up was 17 months (range, 6-66) for all patients and 21.5 months (range, 6-66) for survivors. The 2-year LC, progression-free survival, and OS rates of all patients were 92%, 50%, and 76%, respectively. Univariate analysis revealed histology as a prognostic factor for OS, being higher in adenoid cystic carcinoma and olfactory neuroblastoma than in other tumors. Sixteen grade ≥3 late toxicities were observed in 12 patients (19%), including 11 events resulting in visual impairment; the most common was cataract. There was 1 grade 4 toxicity, and there were no grade 5 toxicities.

Conclusion: SSPT was well tolerated and yielded good LC for sinonasal malignant tumors. Although we consider SSPT to be a leading treatment modality, further studies are required to establish its status as a standard treatment.

Keywords: proton therapy; sinonasal cancer; spot scanning.