Proton Therapy Reduces Treatment-Related Toxicities for Patients with Nasopharyngeal Cancer: A Case-Match Control Study of Intensity-Modulated Proton Therapy and Intensity-Modulated Photon Therapy

Abstract

Purpose: The physical properties of proton therapy allow for decreased dose delivery to nontarget structures. The purpose of this study was to determine if this translates into a clinical benefit by comparing acute and chronic morbidity between patients with nasopharyngeal carcinoma who are treated with intensity-modulated proton therapy (IMPT) and those treated with intensity-modulated radiation therapy (IMRT). Materials and Methods: Patients receiving IMPT for nasopharyngeal cancer from 2011-13 were matched in a 2:1 IMPT to IMRT ratio. Matching criteria were, in order, T-stage, N-stage, radiation dose, chemotherapy type, World Health Organization classification, sex, and age. Results: Ten patients treated with IMPT and 20 matched patients treated with IMRT were included. By the end of treatment, 2 IMPT-treated patients (20%) and 13 IMRTtreated patients (65%) required gastrostomy tube (GT) insertion (P ¼ .020). Patients receiving IMPT had significantly lower mean doses to the oral cavity, brainstem, whole brain, and mandible. Increased mean dose to the oral cavity was associated with a higher rate of GT placement (P , .001), but mean dose to the brainstem, whole brain, and mandible was not. Partitioning analysis showed that no patient required GT insertion if the mean oral cavity dose was ,26 Gy, but all patients with a mean oral cavity dose. 41.8 Gy required GT insertion. Treatment type (IMPT versus IMRT), induction chemotherapy (yes versus no), mean oral cavity dose, mean brainstem dose, and mean mandible dose were entered into the multivariable model. Only higher mean oral cavity dose remained significantly associated with higher GT rates on multivariable analysis http://theijpt.org

Dosimetric advantages of intensity-modulated proton therapy for oropharyngeal cancer compared with intensity-modulated radiation: A case-matched control analysis

“…33 It stands to reason that patients with OPC may similarly benefit, and, indeed, preliminary findings also show an approximately 50% reduction in feeding tube insertion rates for patients with OPC undergoing IMPT compared with historical control patients treated with IMRT. 34 Analyses are currently ongoing for a contemporary case-matched cohort study.…”

Dosimetric Comparison of Pencil-Beam Scanning and Photon-Based Radiation Therapy as a Boost in Carcinoma of Cervix

“…The average volume of PTV in the present study was 134.94 6 34.44 cm 3 . D 95% reported was 20.08 6 0.06 Gy, 20.1 6 0.04…”

“…While the opposed parallel pair geometry should help offset this uncertainty, the authors estimated variability by forcing the density of the bowel in the field to 0.5 g/cm 3 , which is a first-order estimate of the potential range of the different scenarios. Photon plans were designed on the Varian Eclipse Treatment Planning System, version 11.0 (Varian Medical System Inc, Palo Alto, California), with 6-MV flattening filter free photon beams from a Varian True Beam equipped with high definition multileaf collimator.…”

“…It has been reported to further reduce radiationinduced toxicities and to facilitate dose escalation [3]. Recently, pencil beam scanning (PBS), also known as intensitymodulated proton therapy and spot scanning, has become more widespread as a more advanced technique to deliver proton radiation therapy.…”

Quality of Life and Value Considerations in Head and Neck Proton Beam Therapy: The Holy Grail at Last, or the Quest Continues?

“…However, the toxicity story may not be that simple. For example, in a meta-analysis of observational studies in nasal cavity/paranasal sinus cancer, the rate of neurological toxicity was significantly higher with charged particle therapy than with photon therapy (0.2 vs 0.04, respectively, PZ.0002) (1), and the MD Anderson retrospective casecontrol study in nasopharyngeal cancer patients showed a doubling of temporal lobe necrosis with PBT versus that with photon therapy (2 of 10 vs 2 of 20 patients, respectively, P value not given) (2). Because coverage and avoidance compromises are required even in PBT planning, it is possible that PBT dose distributions may exchange certain toxicities related to the intensity modulated radiation therapy IMRT "low-dose bath" (eg, loss of hair or taste) for others related to increased dose heterogeneity (3) or planning and delivery inaccuracies at critical tissue interfaces.…”