International Journal of Particle Therapy最新文献

Purpose: Recent single institution, phase II evidence has demonstrated the feasibility and efficacy of ultra-hypofractionated, preoperative photon therapy in 5 fractions for the treatment of soft tissue sarcoma (STS). Our purpose was to evaluate the dosimetric benefits of modern scanning beam proton therapy compared with conventional photon radiation therapy (RT) for the neoadjuvant treatment of adult extremity STS.

Materials and methods: Existing proton and photon plans for 11 adult patients with STS of the lower extremities previously treated preoperatively with neoadjuvant RT at our center were used to create proton therapy plans using Raystation Treatment Planning System v10.A. Volumes were delineated, and doses reported consistent with International Commission on Radiation Units and Measurements reports 50, 62, and 78. Target volumes were optimized such that 100% clinical target volume (CTV) was covered by 99% of the prescription dose. The prescribed dose was 30 Gy for PT and RT delivered in 5 fractions. For proton therapy, doses are reported in GyRBE = 1.1 Gy. The constraints for adjacent organs at risk (OARs) within 1 cm of the CTV were the following: femur V30Gy ≤ 50%, joint V30Gy < 50%, femoral head V30Gy ≤ 5 cm³, strip V12 ≤ 10%, and skin V12 < 50%. Target coverage goals, OAR constraints, and integral dose were compared by Student t test with P < .05 significance.

Results: A minimum 99% CTV coverage was achieved for all plans. OAR dose constraints were achieved for all proton and photon plans; however, mean doses to the femur (10.7 ± 8.5 vs 16.1 ± 7.7 GyRBE), femoral head (2.0 ± 4.4 vs 3.6 ± 6.4 GyRBE), and proximal joint (1.8 ± 2.4 vs 3.5 ± 4.4 GyRBE) were all significantly lower with PT vs intensity-modulated radiation therapy (IMRT) (all P < .05). Integral dose was significantly reduced for proton vs photon plans. Conformity and heterogeneity indices were significantly better for proton therapy.

Conclusion: Proton therapy maintained target coverage while significantly reducing integral and mean doses to the proximal organs at risk compared with RT. Further prospective investigation is warranted to validate these findings and potential benefit in the management of adult STS.

Purpose: To compare spatially fractionated radiation therapy (GRID) treatment planning techniques using proton pencil-beam-scanning (PBS) and photon therapy.

Materials and methods: PBS and volumetric modulated arc therapy (VMAT) GRID plans were retrospectively generated for 5 patients with bulky tumors. GRID targets were arranged along the long axis of the gross tumor, spaced 2 and 3 cm apart, and treated with a prescription of 18 Gy. PBS plans used 2- to 3-beam multiple-field optimization with robustness evaluation. Dosimetric parameters including peak-to-edge ratio (PEDR), ratio of dose to 90% of the valley to dose to 10% of the peak VPDR(D90/D10), and volume of normal tissue receiving at least 5 Gy (V5) and 10 Gy (V10) were calculated. The peak-to-valley dose ratio (PVDR), VPDR(D90/D10), and organ-at-risk doses were prospectively assessed in 2 patients undergoing PBS-GRID with pretreatment quality assurance computed tomography (QACT) scans.

Results: PBS and VMAT GRID plans were generated for 5 patients with bulky tumors. Gross tumor volume values ranged from 826 to 1468 cm³. Peak-to-edge ratio for PBS was higher than for VMAT for both spacing scenarios (2-cm spacing, P = .02; 3-cm spacing, P = .01). VPDR(D90/D10) for PBS was higher than for VMAT (2-cm spacing, P = .004; 3-cm spacing, P = .002). Normal tissue V5 was lower for PBS than for VMAT (2-cm spacing, P = .03; 3-cm spacing, P = .02). Normal tissue mean dose was lower with PBS than with VMAT (2-cm spacing, P = .03; 3-cm spacing, P = .02). Two patients treated using PBS GRID and assessed with pretreatment QACT scans demonstrated robust PVDR, VPDR(D90/D10), and organs-at-risk doses.

Conclusions: The PEDR was significantly higher for PBS than VMAT plans, indicating lower target edge dose. Normal tissue mean dose was significantly lower with PBS than VMAT. PBS GRID may result in lower normal tissue dose compared with VMAT plans, allowing for further dose escalation in patients with bulky disease.

Purpose: Treatment for bilateral breast cancer with radiation therapy is technically challenging. We evaluated the clinical and dosimetric outcomes of a small series of patients with synchronous bilateral breast cancer, including a photon dosimetric comparison, to identify optimal treatment planning approaches.

Materials and methods: We reviewed a registry of patients (simultaneously) diagnosed with synchronous bilateral breast cancers who underwent postoperative definitive adjuvant proton therapy at our institution between 2012 and 2021. All patients were treated with double-scattered proton or pencil-beam scanning therapies. For comparison, intensity-modulated radiation therapy photon plans optimized for organ sparing and coverage were generated after treatment.

Results: Six patients were included. The median patient age was 66 years; all were female with no history of breast cancer or radiation therapy. Two (33%) patients received breast/chest wall-only treatments, 1 (17%) required breast plus level I axillary treatment to one side and breast plus regional nodal irradiation (RNI) to the other, and 3 (50%) received bilateral breast/chest plus RNI; dosimetric results are reported for each group's median. Analysis showed clinical target coverage was comparable between proton and photon techniques (V95% of 96.4% with proton, 97.8% with photon). However, protons could deliver superior organ sparing at clinically relevant dose metrics for virtually all structures: a 6.7 Gy absolute reduction in the mean heart dose (7.5 Gy with photons to 0.7 Gy with protons), a 47% to 57% relative reduction in D_0.1cm3 to coronary arteries, a 54% relative reduction in lung V20 Gy, and an absolute 7.6 Gy reduction to the brachial plexus. There was also greater esophagus and spinal cord sparing. The overall survival rate was 100% at 1.5 years of median follow-up (0.5-4.9), and all patients were free of disease. For toxicity, all patients had some form of acute side effects: 66% experienced grade 2 breast/chest pain or soreness; 100% had grade 2 radiation dermatitis or skin induration; 33% had grade 2 fatigue; and 17% had grade 2 esophagitis (per the Common Terminology Criteria for Adverse Events [CTCAE] version 5.0; US National Cancer Institute, Bethesda, Maryland). Subacute toxicity (within 6 months) was observed for 17% of patients with delayed onset of grade 3 dermatitis in the setting of preexisting lupus, 17% with a delayed surgical wound complication, and 17% with grade 2 soft tissue fibrosis. No grade 4 or 5 events were observed.

Conclusions: Substantial dose reductions to multiple organs at risk while maintaining target coverage make proton the preferred modality for bilateral breast cancer treatment when available.

Purpose: To compare Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE) in patients with endometrial cancer receiving adjuvant pelvic radiation therapy with proton beam therapy (PT) versus intensity-modulated radiation therapy (IMRT).

Materials and methods: Patients with uterine cancer treated with curative intent who received either adjuvant PT or IMRT between 2014 and 2020 were identified. Patients were enrolled into a prospective registry using a gynecologic-specific subset of PRO-CTCAE designed to assess symptom impact on daily living. Questions included gastrointestinal (GI) symptoms of diarrhea, flatulence, bowel incontinence, and constipation in addition to other pertinent gynecologic, urinary, and other general symptoms. Symptom-based questions were on a 0- to 4-point scale, with grade 3+ symptoms occurring frequently or almost always. Patient-reported toxicity was analyzed at baseline, end of treatment (EOT), and at 3, 6, 9, and 12 months after treatment. Unequal variance t tests were used to determine if treatment type was a significant factor in baseline-adjusted PRO-CTCAE.

Results: Sixty-seven patients met inclusion criteria. Twenty-two received PT and 45 patients received IMRT. Brachytherapy boost was delivered in 73% of patients. Median external beam dose was 45 Gy for both PT and IMRT (range, 45-58.8 Gy). When comparing PRO-CTCAE, PT was associated with less diarrhea at EOT (P = .01) and at 12 months (P = .24) than IMRT. Loss of bowel control at 12 months was more common in patients receiving IMRT (P = .15). Any patient reporting grade 3+ GI toxicity was noted more frequently with IMRT (31% versus 9%, P = .09).

Discussion: Adjuvant PT is a promising treatment for patients with uterine cancer and may reduce patient-reported GI toxicity as compared with IMRT.

Purpose: Radiation therapy is an independent risk factor for adverse sequelae to the oral cavity and dentition in childhood cancer survivors. However, dental toxicities after radiation therapy often are underreported and there are minimal published data on disturbances in tooth development after proton beam therapy (PBT). We present the long-term clinical and radiographic dental findings 8 years after treatment completion for a patient treated with PBT and chemotherapy for rhabdomyosarcoma.

Materials and methods: Clinical follow-up data of patients treated with PBT within the Proton Overseas Programme (POP) is stored in a National Database and curated by a dedicated outcomes unit at the Christie NHS PBT center. This case report was identified from the extraction and analysis of data for pediatric head and neck cancer patients in this database for a service evaluation project.

Results: The permanent dentition in this patient aged 3.5 years at the time of treatment was severely affected with abnormal dental development first observed 3.5 years after treatment completion. PBT delivered mean doses of 30 Gy(RBE = 1.1) to the maxilla and 25.9 Gy(RBE = 1.1) to the mandible.

Conclusion: Significant dental development abnormalities occurred in this pediatric patient, despite doses in areas being lower than the proposed thresholds in the literature. Improved descriptions of dental toxicities and routine contouring of the maxilla and mandible are needed to correlate dosimetric data. The dose to teeth should be kept as low as reasonably possible in younger patients until the dose thresholds for dental toxicities are known.

Purpose: Photon radiation therapy (RT) is important in the treatment of many brain tumors but can negatively affect neurocognition. Proton therapy (PT) can reduce doses to normal brain structures. We compared photon and proton plans to estimate the potential benefit in cognition if the patient were treated with PT.

Materials and methods: We analyzed 23 adult patients with proton and photon plans for the treatment of a primary brain tumor. Cognitive outcomes were predicted using converted equivalent dose (EQD2) with an α/β ratio of 3 to left temporal lobe and normal brain tissue. Risks of cognitive decline on 2 specific tests, the Controlled Oral Word Association Test (COWAT [letter S], a test of verbal fluency) and the Wechler Adult Intelligence Scale (WAIS-IV Coding Test, a test of processing speed) were derived from a previously published model.

Results: Dose reductions to left temporal lobe and normal brain tissue translated into lower estimated probabilities of impairment in specific neurocognitive test scores after PT. With a mean dose reduction from 1490 to 1092 cGy in EQD2 to the left temporal lobe (P < .001), there was reduction in probability of impairment in the COWAT (Letter S) test from 6.8% to 5.4%. Similar results were seen with the normal brain (750 to 451 cGy in EQD2, P < .001), with reduction in probability of impairment in the WAIS-IV Coding test from 5% to 4.1%. Other structures experiencing dose reduction with PT included each cochlea, posterior fossa, each temporal lobe, and each hippocampus.

Conclusion: We confirmed an association between PT and lower doses to brain substructures, which is expected to result in a modest decrease in probability of impairment in neurocognitive test scoring. These findings should be confirmed in prospective cohorts of patients treated with PT.

Introduction: Proton radiation therapy (PBT) may reduce cardiac doses in breast cancer treatment. Limited availability of proton facilities could require significant travel distances. This study assessed factors associated with travel distances for breast PBT.

Materials and methods: Patients receiving breast PBT at the University of Pennsylvania from 2010 to 2021 were identified. Demographic, cancer, and treatment characteristics were summarized. Straight-line travel distances from the department to patients' addresses were calculated using BatchGeo. Median and mean travel distances were reported. Given non-normality of distribution of travel distances, Wilcoxon rank sum or Kruskal-Wallis test was used to determine whether travel distances differed by race, clinical trial participation, disease laterality, recurrence, and prior radiation.

Results: Of 1 male and 284 female patients, 67.8% were White and 21.7% Black. Median travel distance was 13.5 miles with interquartile range of 6.1 to 24.8 miles, and mean travel distance was 13.5 miles with standard deviation of 261.4 miles. 81.1% of patients traveled less than 30 and 6.0% more than 100 miles. Black patients' travel distances were significantly shorter than White patients' and non-Black or non-White patients' travel distances (median = 4.5, 16.5, and 11.3 miles, respectively; P < .0001). Patients not on clinical trials traveled more those on clinical trials (median = 14.7 and 10.2 miles, respectively; P = .032). There was no difference found between travel distances of patients with left-sided versus right-sided versus bilateral disease (P = .175), with versus without recurrent disease (P = .057), or with versus without prior radiation (P = .23).

Conclusion: This study described travel distances and demographic and clinicopathologic characteristics of patients receiving breast PBT at the University of Pennsylvania. Black patients traveled less than White and non-Black or non-White patients and comprised a small portion of the cohort, suggesting barriers to travel and PBT. Patients did not travel further to receive PBT for left-sided or recurrent disease.

Primary adenoid cystic carcinoma of the trachea (ACC-T) is an extremely rare cancer of the central bronchial system. It is usually associated with an excellent prognosis. Surgery is the standard treatment for resectable tumors, while radiation therapy is used for unresectable tumors or medically inoperable patients. Radiation therapy can be delivered with photons, protons, or carbon ion therapy. In this report, we review a case of unresectable ACC-T in a middle-aged female patient who was treated with radiation therapy and review the potential benefits of the different types of radiation therapy.