Neoadjuvant Modified Short-course Radiotherapy for Stage IV Rectal Cancer.

BACKGROUND/AIM: This study aimed to assess the clinical outcomes of neoadjuvant modified short-course radiotherapy (mSC-RT) for rectal metastatic adenocarcinoma. PATIENTS AND METHODS: Data from 14 patients who underwent mSC-RT followed by surgery for primary tumors were retrospectively analyzed. Twelve patients received systemic chemotherapy for 18 weeks. A 2.5 Gy dose twice daily, up to a total dose of 25 Gy in 10 fractions, over 5 consecutive days was administered through mSC-RT. Surgery for primary tumor was performed five weeks (range=3-7 weeks) after mSC-RT. Nine patients underwent adjuvant chemotherapy. The median follow-up was 38.5 months. RESULTS: No patients developed grade ≥3 toxicities before surgery. Three patients developed local failures and 10 died during the follow-up period. The 1-, and 3-year local control rates were 91.7% and 71.3%, respectively. The median overall survival (OS) was 45.1 months. The 1-, and 3-year OS rates were 85.7% and 56.3%, respectively. Patients with stage IVA showed significantly better OS than those with stage IVB disease. CONCLUSION: mSC-RT followed by delayed surgery was well-tolerated and led to good local control in patients with rectal metastatic adenocarcinoma. mSC-RT could be a treatment option for patients with rectal metastatic adenocarcinoma as it is less likely to lead to cessation of systemic chemotherapy.

Neoadjuvant Modified Short-Course Radiotherapy Followed by Delayed Surgery for Locally Advanced Rectal Cancer.

This study aimed to assess the clinical outcomes and predictive factors of neoadjuvant modified short-course radiotherapy (mSC-RT) for locally advanced rectal cancer (LARC). Data from 97 patients undergoing mSC-RT followed by radical surgery for LARC were retrospectively analyzed. A 2.5 Gy dose twice daily up to a total dose of 25 Gy in 10 fractions was administered through mSC-RT, and this was delivered with oral chemotherapy in 95 (97.9%) patients. Radical surgery was performed 6 (range, 3-13) weeks after mSC-RT. The median follow-up among surviving patients was 43 (8-86) months. All patients completed neoadjuvant radiotherapy with no acute toxicity grade ≥ 3. Three- and five-year local control rates were 96.3% and 96.3%, respectively. Three- and five-year overall survival (OS) rates were 92.7% and 79.8%, respectively. Univariate analyses revealed that poor OS was associated with no concurrent administration of capecitabine, C-reactive-protein-to-albumin ratio ≥ 0.053, carcinoembryonic antigen ≥ 3.4 ng/mL, and neutrophil-to-lymphocyte ratio (NLR) ≥ 1.83 (P = 0.045, 0.001, 0.041, and 0.001, respectively). Multivariate analyses indicated that NLR ≥ 1.83 was independently associated with poor OS (p = 0.018). mSC-RT followed by delayed surgery for LARC was deemed feasible and resulted in good clinical outcomes, whereas poor OS was associated with high NLR.

A feasibility study of a hybrid breast-immobilization system for early breast cancer in proton beam therapy.

PURPOSE: We aimed to develop a new breast-immobilizing system for proton beam therapy (PBT) of early breast cancer (EBC) that would provide the optimum breast shape during the treatment as well as increased fixation reliability by reducing the influence of respiratory movement. METHODS: The breast-immobilizing system (HyBIS; hybrid breast-immobilizing system) consists of a whole body immobilization system (WBIS), position-converting device (to change patient position), photo-scanning system, breast cup (made using a three-dimensional printer), breast cup-fitting apparatus, breast cup-holding device (to ensure the breast remains lifted in the supine position), and dedicated stretcher fixed to the WBIS (to carry the patient). We conducted a phantom experiment to evaluate the effect of the HyBIS on breast immobilization during the respiratory cycle. Thirteen markers were embedded in the right breast of a female phantom that simulated respiratory thoracic movement at an amplitude of 15 mm, and their displacements on four-dimensional computed tomography were compared between conditions with and without immobilization by HyBIS. RESULTS: When immobilization was applied with the HyBIS, breast protrusion was maintained in the phantom in the supine treatment position. The mean values of the anteroposterior, superoinferior, lateral, and three-dimensional (3D) displacement of the markers were 2.7 ± 1.7, 0.3 ± 0.5, 0.9 ± 0.8, and 3.1 ± 1.6 mm with HyBIS, and 5.5 ± 2.9, 0.6 ± 0.8, 0.5 ± 0.4, and 5.6 ± 2.9 mm without HyBIS, respectively; thus, the anteroposterior (P = 0.014) and 3D (P = 0.007) displacements significantly improved with HyBIS. CONCLUSIONS: We demonstrated that the HyBIS can help retain the protruded breast shape in the supine position during treatment and can reduce the influence of respiratory movement. Thus, the HyBIS can help to reliably and precisely perform PBT for EBC.

Effect of Film Dressing on Acute Radiation Dermatitis Secondary to Proton Beam Therapy.

PURPOSE: Acute radiation dermatitis (ARD) is one of the most common adverse events of proton beam therapy (PBT), and there is currently no effective method to manage ARD. The purpose of this study was to examine the prophylactic effect of a film dressing using Airwall on PBT-induced ARD compared with standard skin managements. METHODS AND MATERIALS: A total of 271 patients with prostate cancer who were scheduled for PBT at our center were divided into 2 groups based on their own requests: 145 patients (53%) chose Airwall (group A) and 126 patients (47%) received standard treatments (group B). We evaluated irradiated skin every other day during PBT and followed up once a week for a month after completion of PBT. RESULTS: Grade 0, 1, 2, and 3 dermatitis were seen in 2, 122, 21, and 0 and 0, 65, 57, and 4 patients in groups A and B, respectively (P<.001). Numbers of days to grades 1 and 2 ARD development were 34.9 ± 14.3 and 54.7 ± 10.3 and 31.8 ± 11.3 and 54.4 ± 11.6 in groups A and B, respectively. There were no significant differences between the 2 groups. Eighteen patients (12%) in group A who experienced problems in the region covered with Airwall switched to standard skin care after peeling the film off. CONCLUSIONS: Film dressing using Airwall reduced the severity of ARD without delaying the response time of the skin to proton beam irradiation compared with standard skin management. Hence, film dressing is considered a promising measure for preventing ARD secondary to PBT.

Pacemaker malfunction associated with proton beam therapy: a report of two cases and review of literature-does field-to-generator distance matter?

It is well known that radiotherapy causes malfunctions of cardiac implantable electronic devices such as pacemaker (PM) and implantable cardioverter-defibrillator because of incidental neutron production. Here, we report our experience with two cases of PM reset among seven patients with PM who underwent proton beam therapy (PBT) from January 2011 to April 2015 at our centre. Our experience shows PM reset can occur also with abdominal PBT. In both cases, PM reset was not detected by electrocardiogram (ECG) monitoring but was rather discovered by post-treatment programmer analysis. Our cases suggest that PM malfunction may not always be detected by ECG monitoring and emphasize the importance of daily programmer analysis.

Particle therapy for clinically diagnosed stage I lung cancer: comparison with pathologically proven non-small cell lung cancer.

BACKGROUND: The purpose of the present study was to present the treatment outcomes of particle therapy for indeterminate pulmonary nodules (IPNs) diagnosed as stage I non-small cell lung cancer, including a comparative analysis involving pathologically proven lung cancer (PPLC). MATERIAL AND METHODS: A total of 54 patients (57 lesions) who underwent particle therapy for IPNs were enrolled in this study. Median patient age was 76 (range 52-87) years. T-classification was: T1a, 30; T1b, 16; and T2a, 11. Particle therapy using protons or carbon ions was delivered at total doses of 52.8-80 Gy equivalent in 4-26 fractions. The PPLC cohort included 111 patients. RESULTS: The median follow-up time was 41 (range 7-90) months. For all IPN patients, the three-year overall survival, progression-free survival, local control and distant progression-free survival rates were 90%, 72%, 94% and 79%, respectively. Grade 2 toxicities were radiation pneumonitis (19%), dermatitis (9%), rib fracture (2%), chest wall pain (2%) and neuropathy (2%). No ≥grade 3 toxicities were observed. In univariate analysis, the IPN group showed significantly better survival relative to the PPLC group. However, after adjustment for baseline imbalances between these two groups in multivariate analysis, pathological confirmation did not correlate with survival. CONCLUSIONS: Particle therapy for IPNs provided favorable outcomes with minimal toxicities, which may be comparable to those for PPLC patients. Further studies are needed to clarify the optimal management of IPN patients.

Treatment outcomes of particle radiotherapy using protons or carbon ions as a single-modality therapy for adenoid cystic carcinoma of the head and neck.

BACKGROUND AND PURPOSE: The aim of this study was to retrospectively analyse the outcomes of cases of adenoid cystic carcinomas (ACCs) of the head and neck that were treated at a single institution with particle therapy consisting of either protons or carbon ions. METHODS AND MATERIALS: Between February 2002 and March 2012, 80 patients were treated with proton therapy (PT) or carbon ion therapy (CIT) alone. PT and CIT were employed in 40 (50%) patients each, and more than half of the patients received 65.0 GyE in 26 fractions (n=47, 59%). RESULTS: The median duration of follow-up was 38 months (range, 6-115 months). For all patients, the 5-year for overall survival (OS) rate, progression-free survival (PFS) rate, and local control (LC) rate were 63%, 39%, and 75%, respectively. No significant differences between PT and CIT were observed. The 5-year LC rates for T4 and inoperable cases were 66% and 68%, respectively. Twenty-one patients (26%) experienced grade 3 or greater late toxicities, including three patients who developed grade 5 bleeding from nasopharyngeal ulcers. CONCLUSIONS: Particle radiotherapy for ACC achieves favourable LC, and its efficacy in inoperable or T4 cases is promising. There were no significant differences between PT and CIT in terms of OS, PFS and LC.

A retrospective comparison of proton therapy and carbon ion therapy for stage I non-small cell lung cancer.

BACKGROUND AND PURPOSE: This retrospective study aimed to compare the clinical outcomes and late toxicities of proton therapy (PT) with those of carbon ion therapy (CIT) for stage I non-small cell lung cancer (NSCLC). MATERIAL AND METHODS: A total of 111 patients who underwent particle therapy for stage I NSCLC between April 2003 and December 2009 were enrolled in this study. PT (n=70) and CIT (n=41) were delivered to total doses of 52.8-80 GyE in 4-26 fractions and 52.8-70.2 GyE in 4-26 fractions, respectively. The median follow-up time was 41 months. RESULTS: Differences in outcome between the PT and CIT groups regarding 3-year overall survival (72% and 76%, respectively), progression-free survival (44% and 53%, respectively), and local control (81% and 78%, respectively) were not statistically significant. In multivariate analysis, the type of treatment beam did not correlate with overall survival. The severity of late toxicities was comparable between the two groups. CONCLUSIONS: Clinical results in the PT group were comparable to those in the CIT group. However, this study was a retrospective analysis of a highly heterogeneous population. Consequently, more homogeneous prospective data, large multicentric databases and, ideally, randomized trials are warranted.

Long-term outcome of proton therapy and carbon-ion therapy for large (T2a-T2bN0M0) non-small-cell lung cancer.

INTRODUCTION: : Although many reports have shown the safety and efficacy of stereotactic body radiotherapy (SBRT) for T1N0M0 non-small-cell lung cancer (NSCLC), it is rather difficult to treat T2N0M0 NSCLC, especially T2b (>5 cm) tumor, with SBRT. Our hypothesis was that particle therapy might be superior to SBRT in T2 patients. We evaluated the clinical outcome of particle therapy for T2a/bN0M0 NSCLC staged according to the 7th edition of the International Union Against Cancer (UICC) tumor, node, metastasis classification. METHODS: : From April 2003 to December 2009, 70 histologically confirmed patients were treated with proton (n = 43) or carbon-ion (n = 27) therapy according to institutional protocols. Forty-seven patients had a T2a tumor and 23 had a T2b tumor. The total dose and fraction (fr) number were 60 (Gray equivalent) GyE/10 fr in 20 patients, 52.8 GyE/4 fr in 16, 66 GyE/10 fr in 16, 80 GyE/20 fr in 14, and other in four patients, respectively. Toxicities were scored according to the Common Terminology Criteria for Adverse Events, Version 4.0. RESULTS: : The median follow-up period for living patients was 51 months (range, 24-103). For all 70 patients, the 4-year overall survival, local control, and progression-free survival rates were 58% (T2a, 53%; T2b, 67%), 75% (T2a, 70%; T2b, 84%), and 46% (T2a, 43%; T2b, 52%), respectively, with no significant differences between the two groups. The 4-year regional recurrence rate was 17%. Grade 3 pulmonary toxicity was observed in only two patients. CONCLUSION: : Particle therapy is well tolerated and effective for T2a/bN0M0 NSCLC. To further improve treatment outcome, adjuvant chemotherapy seems a reasonable option, whenever possible.

A phase I/II study of gemcitabine-concurrent proton radiotherapy for locally advanced pancreatic cancer without distant metastasis.

PURPOSE: We conducted the study to assess the feasibility and efficacy of gemcitabine-concurrent proton radiotherapy (GPT) for locally advanced pancreatic cancer (LAPC). MATERIALS AND METHODS: Of all 50 patients who participated in the study, 5 patients with gastrointestinal (GI)-adjacent LAPC were enrolled in P-1 (50 Gy equivalent [GyE] in 25 fractions) and 5 patients with non-GI-adjacent LAPC in P-2 (70.2 GyE in 26 fractions), and 40 patients with LAPC regardless of GI-adjacency in P-3 (67.5 GyE in 25 fractions using the field-within-a-field technique). In every protocol, gemcitabine (800 mg/m(2)/week for 3 weeks) was administered concurrently. Every patient received adjuvant chemotherapy including gemcitabine after GPT within the tolerable limit. RESULTS: The median follow-up period was 12.5 months. The scheduled GPT was feasible for all except 6 patients (12%) due to acute hematologic or GI toxicities. Grade 3 or greater late gastric ulcer and hemorrhage were seen in 5 patients (10%) in P-2 and P-3. The one-year freedom from local-progression, progression-free, and overall survival rates were 81.7%, 64.3%, and 76.8%, respectively. CONCLUSION: GPT was feasible and showed high efficacy. Although the number of patients and the follow-up periods are insufficient, the clinical results seem very encouraging.

Clinical results and risk factors of proton and carbon ion therapy for hepatocellular carcinoma.

BACKGROUND: The objective of this study was to evaluate the clinical outcome of proton and carbon ion therapy for hepatocellular carcinoma (HCC). METHODS: In total, 343 consecutive patients with 386 tumors, including 242 patients (with 278 tumors) who received proton therapy and 101 patients (with 108 tumors) who received carbon ion therapy, were treated on 8 different protocols of proton therapy (52.8-84.0 gray equivalents [GyE] in 4-38 fractions) and on 4 different protocols of carbon ion therapy (52.8-76.0 GyE in 4-20 fractions). RESULTS: The 5-year local control and overall survival rates for all patients were 90.8% and 38.2%, respectively. Regarding proton and carbon ion therapy, the 5-year local control rates were 90.2% and 93%, respectively, and the 5-year overall survival rates were 38% and 36.3%, respectively. These rates did not differ significantly between the 2 therapies. Univariate analysis identified tumor size as an independent risk factor for local recurrence in proton therapy, carbon ion therapy, and in all patients. Multivariate analysis identified tumor size as the only independent risk factor for local recurrence in proton therapy and in all patients. Child-Pugh classification was the only independent risk factor for overall survival in proton therapy, in carbon ion therapy, and in all patients according to both univariate and multivariate analyses. No patients died of treatment-related toxicities. CONCLUSIONS: Proton and carbon ion therapies for HCC were comparable in terms of local control and overall survival rates. These therapies may represent innovative alternatives to conventional local therapies for HCC.

The effectiveness of particle radiotherapy for hepatocellular carcinoma associated with inferior vena cava tumor thrombus.

BACKGROUND: The prognosis of patients who have hepatocellular carcinoma (HCC) associated with inferior vena cava tumor thrombus (IVCTT) is very poor, and effective treatment modalities are extremely limited. The objective of this study was to determine the therapeutic efficacy of particle radiotherapy for HCC with IVCTT. METHODS: Between June 2001 and January 2009, 16 evaluable patients who had HCC with IVCTT were treated with particle radiotherapy. They were divided into 2 groups: 6 were treated with curative intent; 10 with palliative intent. The local tumor control rates, overall survival rates, and toxicities were evaluated. RESULTS: All tumors treated with particle radiotherapy remained controlled without local recurrence at the last follow-up. The overall survival rates for the 16 patients at 1 and 3 years were 61.1 and 36.7%, respectively. We observed a significant difference in the survival rates according to treatment policy. The median survival time was 25.4 months for patients treated with curative intent and 7.7 months for those treated with palliative intent. The one-year survival rates were 100.0 and 33.3%, respectively. No Grade 3 or higher treatment-related toxicities were observed. CONCLUSIONS: Particle radiotherapy is thought to be potentially effective and safe for HCC with IVCTT. Considering the current lack of effective and less-invasive local therapy for HCC with IVCTT, particle radiotherapy may therefore be an attractive new therapeutic approach for this type of HCC.

Multi-institutional Phase II study of proton beam therapy for organ-confined prostate cancer focusing on the incidence of late rectal toxicities.

PURPOSE: Proton beam therapy (PBT) is theoretically an excellent modality for external beam radiotherapy, providing an ideal dose distribution. However, it is not clear whether PBT for prostate cancer can clinically control toxicities. The purpose of the present study was to estimate prospectively the incidence of late rectal toxicities after PBT for organ-confined prostate cancer. METHODS AND MATERIALS: The major eligibility criteria included clinical Stage T1-T2N0M0; initial prostate-specific antigen level of ≤20 ng/mL and Gleason score ≤7; no hormonal therapy or hormonal therapy within 12 months before registration; and written informed consent. The primary endpoint was the incidence of late Grade 2 or greater rectal toxicity at 2 years. Three institutions in Japan participated in the present study after institutional review board approval from each. PBT was delivered to a total dose of 74 GyE in 37 fractions. The patients were prospectively followed up to collect the data on toxicities using the National Cancer Institute-Common Toxicity Criteria, version 2.0. RESULTS: Between 2004 and 2007, 151 patients were enrolled in the present study. Of the 151 patients, 75, 49, 9, 17, and 1 had Stage T1c, T2a, T2b, T2c, and T3a, respectively. The Gleason score was 4, 5, 6, and 7 in 5, 15, 80 and 51 patients, respectively. The initial prostate-specific antigen level was <10 or 10-20 ng/mL in 102 and 49 patients, respectively, and 42 patients had received hormonal therapy and 109 had not. The median follow-up period was 43.4 months. Acute Grade 2 rectal and bladder toxicity temporarily developed in 0.7% and 12%, respectively. Of the 147 patients who had been followed up for >2 years, the incidence of late Grade 2 or greater rectal and bladder toxicity was 2.0% (95% confidence interval, 0-4.3%) and 4.1% (95% confidence interval, 0.9-7.3%) at 2 years, respectively. CONCLUSION: The results of the present prospective study have revealed a valuable piece of evidence that PBT for localized prostate cancer can achieve a low incidence of late Grade 2 or greater rectal toxicities.

Surgical spacer placement and proton radiotherapy for unresectable hepatocellular carcinoma.

Few potentially curative treatment options exist apart from hepatic resection for patients with huge hepatocellular carcinoma (HCC). Proton radiotherapy is a promising new modality which has an inherent anti-tumor effect against HCC. However, the application of proton radiotherapy for tumors adjacent to the gastrointestinal tract is restricted because the tolerance dose of the intestine is extremely low. A novel two-step treatment was developed with surgical spacer placement and subsequent proton radiotherapy to administer proton radiotherapy with curative intent. This report presents a case of a patient with a huge unresectable HCC treated by this method who achieved disease-free survival of more than 2 years. This new strategy may potentially be an innovative and standard therapy for unresectable HCC in the near future.

High-dose proton therapy and carbon-ion therapy for stage I nonsmall cell lung cancer.

BACKGROUND: A study was undertaken to evaluate the clinical outcome of particle therapy for stage I nonsmall cell lung cancer (NSCLC). METHODS: From April 2003 to April 2007, 80 patients with stage I NSCLC were treated with proton therapy or carbon-ion therapy (57 with proton therapy and 23 with carbon-ion therapy) using 3 treatment protocols. In the first protocol, 80 gray equivalents (GyE) of proton therapy was given in 20 fractions, and the second proton therapy protocol used 60 GyE in 10 fractions. For carbon-ion therapy, 52.8 GyE was given in 4 fractions. After achieving promising preliminary results for the first protocol, the authors started to use the second proton therapy protocol to shorten the overall treatment time. Carbon-ion therapy was started in 2005, and thereafter, both proton and carbon-ion therapy plans were made for each patient, and the 1 that appeared superior was adopted. Patient age ranged from 48 to 89 years (median, 76 years). Thirty-seven patients were medically inoperable, and 43 refused surgery. Forty-two patients had T1 tumors, and 38 had T2 tumors. RESULTS: The median follow-up period for living patients was 35.5 months. For all 80 patients, the 3-year overall survival, cause-specific survival, and local control rates were 75% (IA: 74%; IB: 76%), 86% (IA: 84%; IB: 88%), and 82% (IA: 87%; IB: 77%), respectively. There were no significant differences in treatment results among the 3 protocols. Grade 3 pulmonary toxicity was observed in only 1 patient. CONCLUSIONS: Proton therapy and carbon-ion therapy are safe and effective for stage I NSCLC. Further investigation of particle therapy for stage I NSCLC is warranted.

[Particle beam radiotherapy with a surgical spacer placement for unresectable sacral chordoma].

Sacral chordomas constitute more than half of all chordomas and have a slower local growth than other bone malignant tumors. Although complete radical resection produces a longer local control and disease-free survival at the initial visit, chordomas are already often too large for complete resection to be possible. Particle radiotherapy consisting of proton and carbon-ion is a promising new modality which has an inherent anti-tumor effect against many types of malignancies. However, the application of particle radiotherapy for tumors adjacent to the gastrointestinal tract like sacral chordoma is restricted because the tolerance dose of the intestine is extremely low. A novel two-step treatment was developed with surgical spacer placement and subsequent proton radiotherapy to administer particle radiotherapy with curative intent. This report presents a case of a patient with a huge sacral chordoma treated by this method. This new strategy may potentially be an innovative and standard therapy for unresectable sacral chordoma in the near future.

[Current status and future of particle radiotherapy at the Hyogo Ion Beam Medical Center].

The Hyogo Ion Beam Medical Center was established in May 2001, a leading project of the Hyogo Cancer Strategy . Its major feature is that both proton and carbon ion beams can be generated. Particle beam radiation therapy had been performed in 2,639 patients as of the end of March 2009. The diseases were prostate cancer, head and neck tumors, liver cancer, lung cancer, and bone soft tissue tumors, in decreasing order of frequency, and these 5 major diseases accounted for 87% of the cases. By beam-type therapy, 2,122 and 517 patients (80 and 20%) were treated with proton and carbon ion beams, respectively. The outcomes surpassed those of surgical therapy realizing cancer therapy without resection. Current problems of particle beam radiation therapy include the unclear effect of differential use of proton and carbon ion beams and the necessity of laying in large-scale equipment, which prevents its dissemination. We are now aiming at the development and clinical application of a laser-driven proton radiotherapy device in cooperation with the Japan Atomic Energy Agency.

Brain injury after proton therapy or carbon ion therapy for head-and-neck cancer and skull base tumors.

PURPOSE: To assess the incidence of early delayed or late morbidity of the brain after particle therapy for skull base tumors and head-and-neck cancers. METHODS AND MATERIALS: Between May 2001 and December 2005, 59 patients with cancerous invasion of the skull base were treated with proton or carbon ion therapy at the Hyogo Ion Beam Medical Center. Adverse events were assessed according to the magnetic resonance imaging findings (late effects of normal tissue-subjective, objective, management, analytic [LENT-SOMA]) and symptoms (Common Terminology Criteria for Adverse Events [CTCAE], version 3.0). Dose-volume histograms were used to analyze the relationship between the dose and volume of the irradiated brain and the occurrence of brain injury. The median follow-up time was 33 months. RESULTS: Of the 48 patients treated with proton therapy and 11 patients treated with carbon ion radiotherapy, 8 (17%) and 7 (64%), respectively, developed radiation-induced brain changes (RIBCs) on magnetic resonance imaging (LENT-SOMA Grade 1-3). Four patients (7%) had some clinical symptoms, such as vertigo and headache (CTCAE Grade 2) or epilepsy (CTCAE Grade 3). The actuarial occurrence rate of RIBCs at 2 and 3 years was 20% and 39%, respectively, with a significant difference in the incidence between the proton and carbon ion radiotherapy groups. The dose-volume histogram analyses revealed significant differences between the brain lobes with and without RIBCs in the actuarial volume of brain lobes receiving high doses. CONCLUSION: Particle therapies produced minimal symptomatic brain toxicities, but sequential evaluation with magnetic resonance imaging detected a greater incidence of RIBCs. Significant differences were observed in the irradiated brain volume between the brain lobes with and without RIBCs.

Physiologic reactions after proton beam therapy in patients with prostate cancer: significance of urinary autoactivation.

PURPOSE: Proton therapy is a sophisticated treatment modality for prostate cancer. We investigated how physiologic factors affected the distribution of autoactivation as detected by positron emission tomography (PET) after proton beam therapy. METHODS AND MATERIALS: Autoactivation was evaluated in 59 patients treated with a 210-MeV proton beam. Data acquisition for autoactivation by PET started 5 minutes after proton irradiation to assess activation. In the first 29 patients, five regions of interest were evaluated: planning target volume (PTV) center, urinary bladder inside the PTV, urinary bladder outside the PTV, rectum (outside the PTV), and contralateral femoral bone head (outside the PTV). In the remaining 30 patients, urine activity was measured directly. In a phantom study autoactivation and its diffusion after proton beam irradiation were evaluated with water or an ice block. RESULTS: Mean activities calculated by use of PET were 629.3 Bq in the PTV center, 555.6 Bq in the urinary bladder inside the PTV, 332.5 Bq in the urinary bladder outside the PTV, 88.4 Bq in the rectum, and 23.7 Bq in the femoral bone head (p < 0.001). Mean urine activity was 679.4 Bq, recorded 10 minutes after therapy completion, and the half-life for urine autoactivation was 4.5 minutes. CONCLUSIONS: Urine is a major diffusion mediator of autoactivation after proton beam therapy. Our results indicate that physiologic factors can influence PET images of autoactivation in the context of proton beam therapy verification.