Abstract
PurposeAdvances in radiotherapy have improved tumor control and reduced toxicity in the management of nasopharyngeal carcinoma (NPC). Local failure remains a problem for some patients with advanced primary tumors, and toxicities are significant given the large treatment volume and tumor proximity to critical structures, even with modern photon-based radiotherapy. Proton therapy has unique dosimetric advantages, and recent technological advances now allow delivery of intensity-modulated proton therapy (IMPT), which can potentially improve the therapeutic ratio in NPC. We report our 2-year clinical outcomes with IMPT for NPC.Materials and MethodsWe retrospectively reviewed treatment records of patients with NPC treated with IMPT at our center. Demographics, dosimetry, tumor response, local regional control (LRC), distant metastasis, overall survival, and acute and late toxicity outcomes were reviewed. Analyses were performed with descriptive statistics and Kaplan-Meier method. Toxicity was graded per Common Terminology Criteria for Adverse Events (version 4.0).ResultsTwenty-six patients were treated from 2015 to 2020. Median age was 48 years (range, 19–73 years), 62% (n = 16) had T3-T4 disease, 92% (n = 24) were node positive, 92% (n = 24) had stage III-IV disease, and 69% (n = 18) had positive results for Epstein-Barr virus. Dose-painted pencil-beam IMPT was used. Most patients (85%; 22 of 26) were treated with 70 Gy(RBE) in 33 fractions once daily; 4 (15%) underwent hyperfractionated accelerated treatment twice daily. All received concurrent cisplatin chemotherapy; 7 (27%) also received induction chemotherapy. All patients (100%) completed the planned radiotherapy, and no acute or late grade 4 or 5 toxicities were observed. At median follow-up of 25 months (range, 4-60), there were 2 local regional failures (8%) and 3 distant metastases (12%). The Kaplan-Meier 2-year LRC, freedom from distant metastasis, and overall survival were 92%, 87%, and 85% respectively.ConclusionIMPT is feasible in locally advanced NPC with early outcomes demonstrating excellent LRC and favorable toxicity profile. Our data add to the growing body of evidence supporting the clinical use of IMPT for NPC.
Highlights
Nasopharyngeal carcinoma (NPC) is a relatively rare cancer that accounts for, 1% of all cancers worldwide [1]
We evaluated our initial experience with intensity-modulated proton therapy (IMPT) in the definitive management of NPC at our institution
Comprehensive treatment of neck target volumes can be delivered with IMPT alone, without combined approaches with photons to address the neck or complex match techniques that were necessary with PS-Proton beam therapy (PT) techniques [13, 14, 25]
Summary
Nasopharyngeal carcinoma (NPC) is a relatively rare cancer that accounts for , 1% of all cancers worldwide [1]. It is uncommon in North America, but the prevalence is significantly greater in certain regions of the world where it is endemic, including Southeast Asia, Northern Africa, and the Middle East. NPC is sensitive to both chemotherapy and radiation. Primary radiotherapy (RT) has long been the mainstay of treatment for NPC. Numerous clinical trials in patients with locally advanced disease established that the addition of chemotherapy to radiation therapy improves local regional control (LRC) and survival, and chemoradiation is the accepted standard of care in these patients [2, 3]
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