Multifield Optimization Intensity Modulated Proton Therapy for Head and Neck Tumors: A Translation to Practice

Abstract

Summary The first fifteen consecutive patients treated with multi-field optimization intensity modulated proton therapy (MFO-IMPT) were able to complete treatment with no need for treatment breaks and no hospitalizations. Ten patients presented with SCC and 5 with ACC. There were no treatment-related deaths and with a median follow-up of 28 months, the overall clinical complete response rate was 93.3%. Early clinical outcomes warrant further investigation of proton therapy in the management of head and neck malignancies. Background We report the first clinical experience and toxicity of multi-field optimization (MFO) intensity-modulated proton therapy (IMPT) for patients with head and neck tumors. Methods Fifteen consecutive patients with head and neck cancer underwent MFO-IMPT with active scanning beam proton therapy. Patients with SCC had comprehensive treatment extending from the base of the skull to the clavicle. The dose for chemoradiation therapy and radiation therapy alone was 70 Gy and 66 Gy, respectively. The robustness of each treatment plan was also analyzed to evaluate sensitivity to uncertainties associated with variations in patient setup and the effect of uncertainties with proton beam range in patients. Proton beam energies during treatment ranged from 72.5 to 221.8 MeV. Spot sizes varied depending on the beam energy and depth of the target, and the scanning nozzle delivered the spot scanning treatment “spot-by-spot” and “layer-by-layer” Results Ten patients presented with squamous cell carcinoma (SCC) and 5 with adenoid cystic carcinoma (ACC). All 15 patients were able to complete treatment with MFO-IMPT with no need for treatment breaks and no hospitalizations. There were no treatment-related deaths and with a median follow-up of 28 months (range: 20-35), the overall clinical complete response rate was 93.3% (95%, confidence interval 68.1% to 99.8%). Xerostomia occurred in all 15 patients as follows; Grade 1 - ten patients, Grade 2 - four patients, and Grade 3 - one patient. Mucositis within the planning target volumes was seen during the treatment of all patients; Grade 1 - one patient, Grade 2 - eight patients, and Grade 3 - six patients. No patient experienced Grade 2 or higher anterior oral mucositis. Conclusions This is the first clinical report of MFO-IMPT for head and neck tumors. Early clinical outcomes are encouraging and warrant further investigation of proton therapy in prospective clinical trials.

Potential proton and photon dose degradation in advanced head and neck cancer patients by intratherapy changes

“…Only one delineated intra therapy CT was available here. However, it was taken after about 4 weeks, a time point that is associated with the largest dose increase in some OARs for IMPT22 and that was used earlier for adaptation in IMPT HNC treatment with encouraging clinical outcome for less advanced HNC 33. Similar to previous studies, we found for IMRT that target dose parameters changed significantly but remained mostly within requirements while OAR dose increase was partly critical, e.g.…”

What are the potential benefits of using proton therapy in Taiwanese cancer patients?

“…However, several recent publications not only showed the feasibility of using spot beam scanning technique in delivering IMPT in head and neck cancer [19][20][21] but also showed that the preliminary results are very promising. [3,22] The potential benefits of IMPT in head and neck cancer mainly are due to sparing of normal tissues from the radiation dose. For ipsilateral lesions such as tonsil or buccal cancers, IMPT has a significantly lower dose than intensity-modulated X-ray (IMRT) in contralateral submandibular and parotid gland, oral cavity, spinal cord, and brain stem.…”

“…Compared to IMRT, IMPT spares substantial dose to these regions [23] and preliminary results were very encouraging for using this technique. [22] The result of a recent study showed that the percentage of oropharyngeal cancer patients requiring nasogastric tube feeding during concurrent chemoradiotherapy (CCRT) was significantly reduced from 46% by IMRT to 19% by IMPT. [24] The clinical outcome of head and neck cancer patients treated by proton therapy, mainly by passive scattering technique, is summarized in Table 2.…”

Dose Comparison between Eclipse Dose Calculation and Fast Dose Calculator in Single- and Multi-Field Optimization Intensity-Modulated Proton Therapy Plans with Various Multi-Beams for Brain Cancer

“…In the present study, we evaluated dose differences of the TPS and the FDC in single-field optimization (SFO) and multi-field optimization (MFO) IMPT [20] for brain cancer with heterogeneity, in order to grasp current potential problems of dose error in IMPT plans designed by the TPS. Additionally, because a proton arc therapy with ultimate multi-fields has dosimetric benefit [21] [22], we wanted to know how the number of fields and beam angles affect the differences for IMPT plans.…”