Evaluation of therapeutic potential of heavy ion therapy for patients with locally advanced prostate cancer

Production and distribution of chromosome aberrations in human lymphocytes by particle beams with different LET

We investigated induction of chromosome aberrations (CA) in human lymphocytes when exposed to 150 MeV and spread out Bragg peak (SOBP) proton beams, and 199 MeV/u carbon beam which are currently widely used for cancer treatment and simultaneously are important components of cosmic radiation. For a comparison, the boron ions of much lower energy 22 MeV/u and a 60Co γ rays were used. Dose-effect curves as well as the distributions of CA were studied using Poisson and Neyman type A statistics. Systematics of experimentally determined parameters, their dependence on applied doses and irradiation quality are presented.

Persistence of radiation-induced aberrations in patients after radiotherapy with C-ions and IMRT

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A follow-up of aberrations in lymphocytes of cancer patients was performed.

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The ratio of dicentrics to translocations declined indicating bone marrow damage.

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Bone marrow exposure was verified by examination of treatment plans.

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Clonal aberrations were also present before therapy and thus not radiation induced.

Background and purpose

Chromosomal aberrations in peripheral blood lymphocytes are a biomarker for radiation exposure and are associated with an increased risk for malignancies. To determine the long-term cytogenetic effect of radiotherapy, we analyzed the persistence of different aberration types up to 2.5 years after the treatment.

Materials and methods

Cytogenetic damage was analyzed in lymphocytes from 14 patients that had undergone C-ion boost + IMRT treatment for prostate cancer. Samples were taken immediately, 1 year and 2.5 years after therapy. Aberrations were scored using the multiplex fluorescence in situ hybridization technique and grouped according to their transmissibility to daughter cells.

Results

Dicentric chromosomes (non-transmissible) and translocations (transmissible) were induced with equal frequencies. In the follow-up period, the translocation yield remained unchanged while the yield of dicentrics decreased to ≈40% of the initial value (p = 0.011 and p = 0.001 for 1 and 2.5 years after compared to end of therapy). In 2 patients clonal aberrations were observed; however they were also found in samples taken before therapy and thus were not radiotherapy induced.

Conclusion

The shift in the aberrations spectrum towards a higher fraction of translocations indicates the exposure of hematopoietic stem and progenitor cells underlining the importance of a careful sparing of bone marrow during radiotherapy to minimize the risk for secondary cancers.

Carbon-ion radiation therapy for prostate cancer

In 1994, carbon-ion radiotherapy was started at the National Institute of Radiological Sciences using the Heavy-Ion Medical Accelerator in Chiba. Between June 1995 and March 2000, two phase I/II dose escalation studies (protocols 9402 and 9703) of hypofractionated carbon-ion radiotherapy for both early- and advance-stage prostate cancer patients had been carried out to establish radiotherapy technique and to determine the optimal radiation dose. To validate the feasibility and efficacy of hypofractionated carbon-ion radiotherapy, a phase II study (9904) was initiated in April 2000 using the shrinking field technique and the recommended dose fractionation (66 gray equivalents in 20 fractions over 5 weeks) obtained from the phase I/II studies, and was successfully completed in October 2003. The data from 175 patients in the phase II study showed the importance of an appropriate use of androgen deprivation therapy according to tumor risk group. Since November 2003, carbon-ion radiotherapy for prostate cancer was approved as "Highly Advanced Medical Technology" from the Ministry of Health, Labor, and Welfare, and since then approximately 1100 patients have received carbon-ion radiotherapy as of July 2011. In this review, we introduce our steps thorough three clinical trials carried out at National Institute of Radiological Sciences, and show the updated data of carbon-ion radiotherapy obtained from approximately 1000 prostate cancer patients. In addition, our recent challenge and future direction will be also described.

Acute toxicity of combined photon IMRT and carbon ion boost for intermediate-risk prostate cancer - acute toxicity of 12C for PC

BACKGROUND

Carbon ion ((12)C) therapy in the treatment of prostate cancer (PC) might result in an improved outcome as compared to low linear energy transfer irradiation techniques. In this study, we present the first interim report of acute side effects of the first intermediate-risk PC patients treated at the GSI (Gesellschaft für Schwerionenforschung) and the University of Heidelberg in an ongoing clinical phase I/II trial using combined photon intensity modulated radiation therapy (IMRT) and (12)C carbon ion boost.

MATERIAL AND METHODS

Fourteen patients (planned accrual: 31 pts) have been treated within this trial so far. IMRT is prescribed to the median PTV at a dose of 30 × 2 Gy; (12)C boost is applied to the prostate (GTV) at a dose of 6 × 3 GyE using raster scan technique. Safety margins added to the clinical target volume were determined individually for each patient based on five independent planning computed tomography (CT)-scans. Acute gastrointestinal (GI) and genitourinary (GU) toxicity was assessed and documented according to the CTCAE Version 3.0.

RESULTS

Radiotherapy was very well tolerated without any grade 3 or higher toxicity. Acute anal bleeding grade 2 was observed in 2/14 patients. Rectal tenesmus grade 1 was reported by three other patients. No further GI symptoms have been observed. Most common acute symptoms during radiotherapy were nocturia and dysuria CTC grade 1 and 2 (12/14). There was no severe acute GU toxicity.

CONCLUSION

The combination of photon IMRT and carbon ion boost is feasible in patients with intermediate-risk PC. So far, the treatment has been well tolerated. Acute toxicity rates were in good accordance with data reported for high dose IMRT alone.

Carbon ion radiotherapy performed as re-irradiation using active beam delivery in patients with tumors of the brain, skull base and sacral region

INTRODUCTION

To asses carbon ion radiation therapy (RT) performed as re-irradiation in 28 patients with recurrent tumors.

MATERIALS AND METHODS

Twenty-eight patients were treated with carbon ion RT as re-irradiation for recurrent chordoma and chondrosarcoma of the skull base (n=16 and n=2), one chordoma and one chondrosarcoma of the os sacrum, high-risk meningioma (n=3), adenoid-cystic carcinoma (n=4) as well as one SCCHN. All patients were treated using active raster scanning, and treatment planning was performed on CT- and MRI-basis. All patients were followed prospectively during follow-up.

RESULTS

In all patients re-irradiation could be applied safely without interruptions. For skull base tumors, local tumor control after re-irradiation was 92% at 24 months and 64% at 36 months. Survival after re-irradiation was 86% at 24 months, and 43% at 60 months. In all three meningiomas treated with C12 for re-irradiation, the tumor recurrence was located within the former RT-field. Two patients developed tumor progression at 6 months, and in one patient the tumor remained stable for 67 months. In patients with head-and-neck tumors, three patients developed local tumor progression at 12, 24 and 29 months after re-irradiation. Median local progression-free survival was 24 months. For sacral tumors, re-irradiation offered palliation with tumor control for 24 and 36 months.

CONCLUSION

Due to the physical characteristics particle therapy offers a new treatment modality in cases with tumor recurrences. With carbon ions, the additional biological benefits may be exploited for long-term tumor control. Further evaluation in a larger patients' cohort will be performed in the future.

De novo detrusor underactivity after laparoscopic radical prostatectomy

OBJECTIVE

The aim of this study was to investigate bladder function following laparoscopic radical prostatectomy, with a focus on de novo detrusor underactivity.

METHODS

Records on pre- and postoperative urodynamic studies were retrospectively investigated in 110 patients who underwent laparoscopic radical prostatectomy. Patients exhibiting de novo detrusor underactivity were selected on the basis of an overt strain voiding pattern during the postoperative pressure flow study with detrusor pressure at a maximum flow rate <10 cm H(2)O accompanied by an increase in abdominal pressure. In these patients, a follow-up urodynamic study was performed to assess subsequent long-term changes in the bladder function.

RESULTS

Of the 110 patients, 10 (9.1%) were observed to exhibit de novo detrusor underactivity during the postoperative urodynamic study. During the voiding phase of the pre- and postoperative pressure flow study in these 10 patients, the mean detrusor pressure at maximum flow rate showed a significant decrease postoperatively from 57.6 to 3.0 cm H(2)O (P < 0.001), although the mean abdominal pressure at maximum flow rate significantly increased from 23.1 to 102.5 cm H(2)O (P < 0.001). The follow-up urodynamic study performed on seven patients at 36 months following surgery revealed no significant change in each urodynamic parameter. De novo detrusor underactivity persisted even over the long term following surgery, and no improvement in bladder function was observed.

CONCLUSIONS

Detrusor contractility may be impaired during radical prostatectomy. Postoperative detrusor underactivity following radical prostatectomy seems to be an irreversible phenomenon persisting even over the long term.

Ion beam radiobiology and cancer: time to update ourselves

High-energy protons and carbon ions exhibit an inverse dose profile allowing for increased energy deposition with penetration depth. Additionally, heavier ions like carbon beams have the advantage of a markedly increased biological effectiveness characterized by enhanced ionization density in the individual tracks of the heavy particles, where DNA damage becomes clustered and therefore more difficult to repair, but is restricted to the end of their range. These superior biophysical and biological profiles of particle beams over conventional radiotherapy permit more precise dose localization and make them highly attractive for treating anatomically complex and radioresistant malignant tumors but without increasing the severe side effects in the normal tissue. More than half a century since Wilson proposed their use in cancer therapy, the effects of particle beams have been extensively investigated and the biological complexity of particle beam irradiation begins to unfold itself. The goal of this review is to provide an as comprehensive and up-to-date summary as possible of the different radiobiological aspects of particle beams for effective application in cancer treatment.

Motion compensation with a scanned ion beam: a technical feasibility study

Background

Intrafractional motion results in local over- and under-dosage in particle therapy with a scanned beam. Scanned beam delivery offers the possibility to compensate target motion by tracking with the treatment beam.

Methods

Lateral motion components were compensated directly with the beam scanning system by adapting nominal beam positions according to the target motion. Longitudinal motion compensation to mitigate motion induced range changes was performed with a dedicated wedge system that adjusts effective particle energies at isocenter.

Results

Lateral compensation performance was better than 1% for a homogeneous dose distribution when comparing irradiations of a stationary radiographic film and a moving film using motion compensation. The accuracy of longitudinal range compensation was well below 1 mm.

Conclusion

Motion compensation with scanned particle beams is technically feasible with high precision.

Influence of multiple genetic polymorphisms on genitourinary morbidity after carbon ion radiotherapy for prostate cancer

PURPOSE

To investigate the genetic risk of late urinary morbidity after carbon ion radiotherapy in prostate cancer patients.

METHODS AND MATERIALS

A total of 197 prostate cancer patients who had undergone carbon ion radiotherapy were evaluated for urinary morbidity. The distribution of patients with dysuria was as follows: Grade 0, 165; Grade 1, 28; and Grade 2, 4 patients. The patients were divided (2:1) consecutively into the training and test sets and then categorized into control (Grade 0) and case (Grade 1 or greater) groups. First, 450 single nucleotide polymorphisms (SNPs) in 118 candidate genes were genotyped in the training set. The associations between the SNP genotypes and urinary morbidity were assessed using Fisher's exact test. Then, various combinations of the markers were tested for their ability to maximize the area under the receiver operating characteristics (AUC-ROC) curve analysis results. Finally, the test set was validated for the selected markers.

RESULTS

When the SNP markers in the SART1, ID3, EPDR1, PAH, and XRCC6 genes in the training set were subjected to AUC-ROC curve analysis, the AUC-ROC curve reached a maximum of 0.86. The AUC-ROC curve of these markers in the test set was 0.77. The SNPs in these five genes were defined as "risk genotypes." Approximately 90% of patients in the case group (Grade 1 or greater) had three or more risk genotypes.

CONCLUSIONS

Our results have shown that patients with late urinary morbidity after carbon ion radiotherapy can be stratified according to the total number of risk genotypes they harbor.

Radiobiological characterization of human tumor cell multilayers after conventional and particle irradiation

The goal of this study was to establish planar multilayers from human tumor cells (WiDr and SiHa) as a model for irradiation of solid tumors. In addition to using conventional X rays (250 kV) as a reference standard, multilayers were tested for their suitability in cell survival studies with heavy-ion irradiation ((12)C(6+)) in the plateau and the extended Bragg peak with a scanned ion beam. Multilayers of both cell lines showed decreased survival compared to the corresponding monolayers after both X and heavy-ion irradiation. This multicellular sensitization effect is in contrast to the multicellular resistance or contact effect commonly described in the literature. Flow cytometry measurements showed an arrest of irradiated SiHa cells in G(2)/M phase. In contrast to the transient arrest of the monolayers, the multilayers stayed in a prolonged arrest. After Bragg-peak irradiation of monolayers, the arrest time was increased by 12-24 h, and more cells were arrested than with X rays. For multilayers, there were no differences between G(2) arrest after X rays and heavy ions for the entire observation period.

Particle therapy in prostate cancer: a review

While dose escalation is proving important to achieve satisfactory long-term outcomes in prostate cancer, the optimal radiation modality to deliver the treatment is still a topic of debate. Charged particle beams can offer improved dose distributions to the target volume as compared to conventional 3D-conformal radiotherapy, with better sparing of surrounding healthy tissues. Exquisite dose distributions, with the fulfillment of dose-volume constraints to normal tissues, however, can also be achieved with photon-based intensity-modulated techniques. This review summarizes the literature on the use of particle therapy in prostate cancer and attempts to put in perspective its relative merits compared to current photon-based radiotherapy.

Current status of radiotherapy with proton and light ion beams

Several model studies have shown potential clinical advantages with charged particles (protons and light ions) compared with 3D-conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) in many disease sites. The newly developed intensity-modulated proton therapy (IMPT) often yields superior dose distributions to photon IMRT, with the added advantage of a significant reduction in the volume of healthy normal tissues exposed to low-to-medium doses. Initially, the major emphasis in clinical research for proton and light ion therapy was dose escalation for inherently radioresistant tumors, or for lesions adjacent to critical normal structures that constrained the dose that could be safely delivered with conventional x-ray therapy. Since the advent of IMRT the interest in particle therapy has gradually shifted toward protocols aimed at morbidity reduction. Lately the emphasis has mostly been placed on the potential for reduced risk of radiation-induced carcinogenesis with protons. Compared with 3D-CRT, a 2-fold increase has been theoretically estimated with the use of IMRT due to the larger integral volumes. In the pediatric setting, due to a higher inherent susceptibility of tissues, the risk could be significant, and the benefits of protons have been strongly emphasized in the literature. There is a significant expansion of particle therapy facilities around the world. Increasing public awareness of the potential benefits of particle therapy and wider accessibility for patients require that treating physicians stay abreast of the clinical indications of this radiotherapy modality. The article reviews the available literature for various disease sites in which particle therapy has traditionally been considered to offer clinical advantages and to highlight current lines of clinical research. The issue of radiation-induced second malignancies is examined in the light of the controversial epidemiological evidence available. The cost-effectiveness of particle therapy is also discussed.

Radiation Therapy With Charged Particles

Charged particle beams can offer an improved dose conformation to the target volume as compared with photon radiotherapy, with better sparing of normal tissue structures close to the target. In addition, beams of ions heavier than (4)He exhibit a strong increase of the linear energy transfer in the Bragg peak as compared with the entrance region. These physical and biological properties are much more favorable than in photon radiotherapy. As a consequence, particle therapy with protons and heavy ions has gained increasing interest worldwide, and many clinical centers are considering introducing radiation therapy with charged particles. This contribution summarizes the physical and technical principles of charged particle therapy with protons and heavy ions. It briefly reviews the clinical experience gathered so far with proton therapy and gives a more detailed summary of the recent results in carbon ion therapy of skull base tumors, head and neck tumors, non-small-cell lung cancer, hepatocellular carcinomas, bone and soft-tissue sarcomas, and prostate cancer.

Carbon ion radiation therapy for prostate cancer: results of a prospective phase II study

BACKGROUND AND PURPOSE

To determine the efficacy and feasibility of carbon ion radiotherapy (C-ion RT) for prostate cancer.

PATIENTS AND METHODS

Between April 2000 and November 2003, 175 patients received C-ion RT using a recommended dose fractionation (66.0 GyE/20 fractions) established from prior studies. C-ion RT alone was performed for 33 patients constituting a low-risk group (Stage < or =T2a and PSA <20 ng/ml and Gleason score < or =6); the remaining 142 high-risk patients received an additional androgen deprivation therapy (ADT).

RESULTS

The 4-year overall survival and bNED rates were 91% and 87%, respectively. Local control was achieved in all but one patient. The 4-year bNED rates were 87% in the low-risk group and 88% in the high-risk group. In very advanced diseases (Stage > or= T3a or PSA > or= 20 ng/ml or Gleason score > or =8), there was significant difference in the bNED rate according to period of ADT administration (ADT > or =24 months: 93%, ADT <24 months: 73%, p<0.01). Grade 2 late toxicities developed in 4 patients (2%) for the rectum and 9 patients (5%) for the genitourinary system but no Grade 3 or higher toxicity was observed.

CONCLUSIONS

The effectiveness of C-ion RT for prostate cancer has been well confirmed. Based on these results, new study of a C-ion RT modified for the administration strategy of ADT according to the patient risk has been started by dividing patients into 3 groups, high-risk, intermediate-risk, and low-risk.

On the detector arrangement for in-beam PET for hadron therapy monitoring

In-beam positron emission tomography (in-beam PET) is currently the only method for an in situ monitoring of highly tumour-conformed charged hadron therapy. At the experimental carbon ion tumour therapy facility, running at the Gesellschaft für Schwerionenforschung, Darmstadt, Germany, all treatments have been monitored by means of a specially adapted dual-head PET scanner. The positive clinical impact of this project triggered the construction of a hospital-based hadron therapy facility, with in-beam PET expected to monitor more delicate radiotherapeutic situations. Therefore, we have studied possible in-beam PET improvements by optimizing the arrangement of the gamma-ray detectors. For this, a fully 3D, rebinning-free, maximum likelihood expectation maximization algorithm applicable to several closed-ring or dual-head tomographs has been developed. The analysis of beta(+)-activity distributions simulated from real-treatment situations and detected with several detector arrangements allows us to conclude that a dual-head tomograph with narrow gaps yields in-beam PET images with sufficient quality for monitoring head and neck treatments. For monitoring larger irradiation fields, e.g. treatments in the pelvis region, a closed-ring tomograph was seen to be highly desirable. Finally, a study of the space availability for patient and bed, tomograph and beam portal proves the implementation of a closed-ring detector arrangement for in-beam PET to be feasible.

Hypofractionated radiotherapy with carbon ion beams for prostate cancer

PURPOSE

Analysis of the results of hypofractionated conformal carbon ion radiotherapy for localized prostate cancer was performed, with special regard to normal tissue morbidity and biochemical relapse-free rate (bNED).

METHODS AND MATERIALS

Analysis was performed for 201 patients treated with the dose fractionation regimen established during three clinical trials performed between June 1995 and February 2004. Outcomes were measured in terms of toxicity, survival, freedom from local recurrence, and bNED.

RESULTS

No Grade 3 or higher toxicities were observed in either the rectum or genitourinary system, and the incidences of Grade 2 rectum or genitourinary morbidity were only 1.0% and 6.0%, respectively. The overall 5-year biochemical relapse-free survival was 83.2% without any local recurrence. Gleason score, initial PSA, and T stage were all significant prognostic factors for bNED, which was 97.1% in patients with Gleason score < or =7 and initial PSA <20 ng/mL.

CONCLUSION

Hypofractionated carbon ion radiotherapy with the established dose fractionation regimen yielded satisfactory bNED without local recurrence and with minimal morbidity. Long-term results are necessary to confirm the utility of carbon ion radiotherapy in the treatment of localized prostate cancer.

Fragmentation of water by heavy ions

Absolute cross sections for fragmentation of water molecules by C3+ and O5+ ions over an energy region where the Bragg peak maximizes were measured for ionization, electron capture, and electron loss channels. A collision regime where sigmaSigmaOq+> or =sigmaH2O+ was reached for the first time, producing large abundances of H+ and O+ fragments in comparison to proton impact. Our findings have straightforward implications in the subsequent fast chemistry at the ionization site and on the O production in the first stages of water radiolysis. An unexpected channel-independent relationship between the cross sections for the fragmentation products, which is also approximately independent of the particle type, energy, and charge state, is found. A model is presented to explain such behavior allowing the cross sections of all fragmentation products to be obtained from single and double electron removal cross sections.

Treatment planning for carbon ion radiotherapy in Germany: Review of clinical trials and treatment planning studies

The GSI carbon ion radiotherapy facility established the first completely active beam shaping system for heavy ions, using energy variation on the synchrotron and pencil beam scanning. The introduction of an active beam shaping system for carbon ions has considerable impact on the design of the treatment planning system (TPS). The TPS has to account for the capability of the beam delivery and the biological modelling, which is needed to calculate the RBE for the resulting varying depth dose modulation. The TPS used in clinical routine with carbon ions is described and its use in treatment planning studies are outlined. A clinical trial with carbon ion therapy as primary therapy for chordoma and chondrosarcoma of the base of skull has been completed in 2001. Currently, carbon ion therapy as a boost treatment together with conventional conformal photon therapy or IMRT is under investigation in clinical trials for adenoid cystic carcinoma, chordoma and chondrosarcoma of the cervical spine and sacrococcygeal chordoma. Treatment planning studies comparing carbon ion therapy with IMRT, using optimization of combination therapy, and optimization of beam-line design have already been completed. Analysis of uncertainties in treatment planning has been started with the investigation of range uncertainties stemming from CT imaging. Uncertainties coming from the beam delivery play only a minor role. An attempt to asses the uncertainties introduced in treatment plans by the biological modelling, was done, using phantom verification of calculated cell survival levels. The clinical trials and planning studies are of special importance for the upcoming new clinical ion facility of the Heidelberg university hospital.