Treatment-Related Complications and Functional Results after Ruthenium-106 Brachytherapy in Small to Medium Size Uveal Melanomas (Part 2)

PURPOSE

To analyze the treatment-related complications after ruthenium-106 brachytherapy in patients with uveal melanoma in terms of radiation-induced optic neuropathy, maculopathy and retinopathy, radiation-related vitreous hemorrhage, and retinal detachment, as well as secondary glaucoma and radiogenic cataract. In addition, the course of visual acuity was analyzed.

PATIENTS/METHODS AND MATERIALS

This retrospective study included 608 patients treated with ruthenium-106 brachytherapy between January 2008 and December 2010 at the Department of Ophthalmology, University Hospital Essen. The follow-up time was 11 years. The occurrence of the radiation-induced complications was analyzed using the Kaplan-Meier method. Cox regression was used for univariate and multivariate risk factor analyses. Hazard ratios were calculated for each variable.

RESULTS

Regarding the complications, 34% (N = 207) of the patients had no reported side effects or complications during follow-up. Radiation optic neuropathy was observed in 18.8% (N = 114) of the patients, with a median time to onset of 16 months (range: 3 - 78 months). Radiation maculopathy occurred in 8.2% (N = 50) after a median time of 17 months (range: 3 - 67 months). Radiation retinopathy was observed in 20.1% (N = 122), with a median time to onset of 21 months (range: 6 - 67 months). Secondary glaucoma developed in 9.7% of the patients (N = 53) and radiogenic cataract in 46.8% (N = 227). Vitreous hemorrhage (11.8%, N = 72) and scleral necrosis (2.1%, N = 13) occurred relatively rarely.

CONCLUSION

The observed radiogenic complication rate is comparable with that reported in previous studies.

Tumor- and Radiation-Related Complications after Ruthenium-106 Brachytherapy in Small to Medium Uveal Melanomas (Part 1)

PURPOSE

The purpose of this study was to analyze tumor-related complications after ruthenium-106 brachytherapy in patients with uveal melanoma, with respect to local tumor control, insufficient radiation response, enucleation, and metastasis rate.

PATIENTS/METHODS AND MATERIALS

This retrospective study included 608 patients treated consecutively with ruthenium-106 brachytherapy between January 2008 and December 2010 at the Department of Ophthalmology, University Hospital Essen. The occurrence of radiation-induced results was analyzed by estimating the risk by applying the Kaplan-Meier method, i.e., the "time to event" analysis. The Cox model test was used for the univariate and multivariate risk factor analyses. The median follow-up was 51 months after primary treatment.

RESULTS

Tumor recurrence was found in 21 patients (3.5%) and repeated treatment due to insufficient effect after the initial ruthenium-106 brachytherapy was performed in 40 patients (6.6%). The 5-year cumulative risk of recurrence was 4.0% and that of insufficient effect was 7.3%. Thirteen patients (2.1%) underwent a secondary enucleation; 8 because of a local recurrence and 5 because of severe post-brachytherapy complications. The cumulative enucleation risk was 2.3% after 5 years and 2.9% after 10 years, corresponding to eye preservation of 97.7 and 97.1%, respectively. In forty-two patients (7.2%), metastatic disease was diagnosed during the follow-up. The metastatic rate as calculated by the Kaplan-Meier method was 9.0, and 13.1% at 5 and 10 years, respectively.

CONCLUSION

Our study demonstrated that ruthenium-106 brachytherapy is an excellent treatment option for achieving local tumor control and eye preservation in well-selected patients. The metastatic rate is in agreement with that of previous studies analyzing small to medium size uveal melanomas.

Long-Term Follow-Up of Patients with Conjunctival Lymphoma after Individualized Lens-Sparing Electron Radiotherapy: Results from a Longitudinal Study

Irradiation with electrons is the primary treatment regime for localized conjunctival low-grade lymphomas. However, radiation-induced cataracts are a major cause of treatment-related morbidity. This study investigates whether lens-sparing electron irradiation produces sufficient disease control rates while preventing cataract formation. All consecutive patients with strictly conjunctival, low-grade Ann Arbor stage IE lymphoma treated with superficial electron irradiation between 1999 and 2021 at our department were reviewed. A total of 56 patients with 65 treated eyes were enrolled with a median follow-up of 65 months. The median dose was 30.96 Gy. A lens-spearing technique featuring a hanging rod blocking the central beam axis was used in 89.2% of all cases. Cumulative incidences of 5- and 10-year infield recurrences were 4.3% and 14.6%, incidences of 5- and 10-year outfield progression were 10.4% and 13.4%. We used patients with involvement of retroorbital structures treated with whole-orbit photon irradiation without lens protection-of which we reported in a previous study-as a control group. The cumulative cataract incidence for patients treated with electrons and lens protection was significantly lower (p = 0.005) when compared to patients irradiated without lens protection. Thus, electrons are an effective treatment option for conjunctival low-grade lymphomas. The presented lens-sparing technique effectively prevents cataract formation.

30 years of ocular proton therapy, the Nice view

PURPOSE

Radiotherapy with protons (PT) is a standard treatment of ocular tumors. It achieves excellent tumor control, limited toxicities, and the preservation of important functional outcomes, such as vision. Although PT may appear as one homogenous technique, it can be performed using dedicated ocular passive scattering PT or, increasingly, Pencil Beam Scanning (PBS), both with various degrees of patient-oriented customization.

MATERAIAL AND METHODS

MEDICYC PT facility of Nice are detailed with respect to their technical, dosimetric, microdosimetric and radiobiological, patient and tumor-customization process of PT planning and delivery that are key. 6684 patients have been treated for ocular tumors (1991-2020). Machine characteristics (accelerator, beam line, beam monitoring) allow efficient proton extraction, high dose rate, sharp lateral and distal penumbrae, and limited stray radiation in comparison to beam energy reduction and subsequent straggling with high-energy PBS PT. Patient preparation before PT includes customized setup and image-guidance, CT-based planning, and ocular PT software modelling of the patient eye with integration of beam modifiers. Clinical reports have shown excellent tumor control rates (∼95%), vision preservation and limited toxicity rates (papillopathy, retinopathy, neovascular glaucoma, dry eye, madarosis, cataract).

RESULTS

Although demanding, dedicated ocular PT has proven its efficiency in achieving excellent tumor control, OAR sparing and patient radioprotection. It is therefore worth adaptations of the equipments and practice.

CONCLUSIONS

Some of these adaptations can be transferred to other PT centers and should be acknowledeged when using non-PT options.

A Review of Boron Neutron Capture Therapy: Its History and Current Challenges

Mechanism of Action

External beam, whether with photons or particles, remains as the most common type of radiation therapy. The main drawback is that radiation deposits dose in healthy tissue before reaching its target. Boron neutron capture therapy (BNCT) is based on the nuclear capture and fission reactions that occur when ¹⁰B is irradiated with low-energy (0.0025 eV) thermal neutrons. The resulting ¹⁰B(n,α)⁷Li capture reaction produces high linear energy transfer (LET) α particles, helium nuclei (⁴He), and recoiling lithium-7 (⁷Li) atoms. The short range (5-9 μm) of the α particles limits the destructive effects within the boron-containing cells. In theory, BNCT can selectively destroy malignant cells while sparing adjacent normal tissue at the cellular levels by delivering a single fraction of radiation with high LET particles.

History

BNCT has been around for many decades. Early studies were promising for patients with malignant brain tumors, recurrent tumors of the head and neck, and cutaneous melanomas; however, there were certain limitations to its widespread adoption and use.

Current Limitations and Prospects

Recently, BNCT re-emerged owing to several developments: (1) small footprint accelerator-based neutron sources; (2) high specificity third-generation boron carriers based on monoclonal antibodies, nanoparticles, among others; and (3) treatment planning software and patient positioning devices that optimize treatment delivery and consistency.

Ocular proton therapy, pencil beam scanning high energy proton therapy or stereotactic radiotherapy for uveal melanoma; an in silico study

PURPOSE

In radiotherapy, the dose and volumes of the irradiated normal tissues is correlated to the complication rate. We assessed the performances of low-energy proton therapy (ocular PT) with eye-dedicated equipment, high energy PT with pencil-beam scanning (PBS) or CyberKnife^R  -based stereotactic irradiation (SBRT).

MATERIAL AND METHODS

CT-based comparative dose distribution between external beam radiotherapy techniques was assessed using an anthropomorphic head phantom. The prescribed dose was 60Gy_RBE in 4 fractions to a typical posterior pole uveal melanoma. Clinically relevant structures were delineated, and doses were calculated using radiotherapy treatment planning softwares and measured using Gafchromic dosimetry films inserted at the ocular level.

RESULTS

Precision was significantly better with ocular PT than both PBS or SBRT in terms of beam penumbra (80%-20%: laterally 1.4 vs. ≥10mm, distally 0.8 vs. ≥2.5mm). Ocular PT duration was shorter, allowing eye gating and lid sparing more easily. Tumor was excellent with all modalities, but ocular PT resulted in more homogenous and conformal dose compared to PBS or SBRT. The maximal dose to ocular/orbital structures at risk was smaller and often null with ocular PT compared to other modalities. Mean dose to ocular/orbital structures was also lower with ocular PT. Structures like the lids and lacrimal punctum could be preserved with ocular PT using gaze orientation and lid retractors, which is easier to implement clinically than with the other modalities. The dose to distant organs was null with ocular PT and PBS, in contrast to SBRT.

CONCLUSIONS

ocular PT showed significantly improved beam penumbra, shorter treatment delivery time, better dose homogeneity, and reduced maximal/mean doses to critical ocular structures compared with other current external beam radiation modalities. Similar comparisons may be warranted for other tumor presentations.

Scleral necrosis after brachytherapy for uveal melanoma: Analysis of risk factors

BACKGROUND

Radiation-induced scleral necrosis (RISN) is a rare, but a serious complication of brachytherapy for uveal melanoma. We aimed at analysing the incidence, timing and risk factors associated with development of RISN in a large institutional series.

METHODS

All consecutive cases with brachytherapy for uveal melanoma treated by the Departments of Ophthalmology and Radiotherapy at University Hospital Essen between 1999 and 2016 were eligible. Development of RISN during the post-treatment follow-up was recorded. A 1:2 propensity score matched case-control study was performed for the evaluation of the prognostic value of different tumour- and treatment-associated parameters.

RESULTS

RISN was documented in 115 (2.9%) of 3960 patients with uveal melanoma included in the final analysis, and occurred at the mean 30.3 months (range: 1.26-226 months) after brachytherapy. In the whole cohort, younger age (p = 0.042), plaque type (p = 0.001) and ciliary body involvement (p < 0.0001) were independently associated with the RISN occurrence. In the case-control study, multivariable weighted proportional hazard analysis discovered the association of the following additional tumour- and treatment-associated characteristics with RISN: posterior tumour margin anterior to equatorial region (p = 0.0003), extraocular tumour extension (p = <0.0001), scleral contact dose (p = <0.0001), conjunctival dehiscence after therapy (p = 0.0001), disinsertion of the superior rectus muscle (p = 0.001) and the glaucoma medication (p = 0.014).

CONCLUSIONS

Our study confirms RISN as a rare complication, which might occur even years later after the brachytherapy for uveal melanoma. Alongside with scleral dose five other tumour and therapy related factors predict the risk of RISN after brachytherapy for uveal melanoma were established.

[Results of surgical and radiotherapeutic treatment of adenoid cystic carcinoma of the salivary glands]

Surgical treatment in patients with rare adenoid cystic carcinoma (ACC) of the salivary glands is considered to be the state of the art. With respect to an additional radiotherapy there are different approaches regarding the type of radiotherapy and timing. In this study the overall survival and recurrence-free survival in 52 individuals with salivary gland ACC who were treated at the University Hospital in Essen and received irradiation with fast neutrons and photons (mixed beam technique) either A) immediately following surgical treatment or B) only after the appearance of local recurrence were compared. Group A (n = 28, first diagnosis, FD September 1991-September 2009) received adjuvant radiotherapy immediately postoperative, group B (n = 24, FD June 1979-November 2001) underwent primarily surgical tumor resection according to the treatment regimen at that time and were irradiated only on the appearance of a local recurrence. In comparison to group B, patients in group A showed a lower recurrence rate and a significantly longer local relapse-free survival. Group B, however, showed a significantly higher overall survival. The frequency of distant metastasis occurred equally in both groups but the onset of distant metastasis was significantly earlier in group A. In general, overall survival was negatively influenced by distant metastasis. The local recurrence rate was very high after primary surgical treatment only. The immediate adjuvant high-linear energy transfer (LET) radiotherapy reduced the local recurrence rates. Irradiation after the appearance of a recurrence had a positive influence on overall survival. Overall, definitive high-LET radiotherapy in the mixed beam technique enabled high local control rates both primarily postoperative and also locoregional recurrences.

18 F-FDG PET/MRI vs MRI in patients with recurrent adenoid cystic carcinoma

OBJECTIVES

To evaluate and compare the diagnostic potential of ¹⁸ F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (¹⁸ FDG-PET/MRI) and MRI for recurrence diagnostics after primary therapy in patients with adenoid cystic carcinoma (ACC).

METHODS

A total of 32 dedicated head and neck ¹⁸ F-FDG PET/MRI datasets were included in this analysis. MRI and ¹⁸ F-FDG PET/MRI datasets were analyzed in separate sessions by two readers for tumor recurrence or metastases.

RESULTS

Lesion-based sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were 96%, 84%, 90%, 93%, and 91% for ¹⁸ F-FDG PET/MRI and 77%, 94%, 95%, 73%, and 84% for MRI, resulting in a significantly higher diagnostic accuracy of ¹⁸ F-FDG PET/MRI compared to MRI (P < .005).

CONCLUSION

¹⁸ F-FDG PET/MRI is superior to MRI in detecting local recurrence and metastases in patients with ACC of the head and neck. Especially concerning its negative predictive value, ¹⁸ F-FDG PET/MRI outperforms MRI.

Monte Carlo Simulation of the Treatment of Uveal Melanoma Using Measured Heterogeneous 106Ru Plaques

Background/Aims

Ruthenium plaques are used for the treatment of ocular tumors. The aim of this work is the comparison between simulated absorbed dose distributions tallied in an anthropomorphic phantom, obtained from ideal homogeneous plaques, and real eye plaques in which the actual heterogeneous distribution of ¹⁰⁶Ru was measured. The placement of the plaques with respect to the tumor location was taken into consideration to optimize the effectiveness of the treatment.

Methods

The generic CCA and CCB, and the specific CCA1364 and CCB1256 ¹⁰⁶Ru eye plaques were modeled with the Monte Carlo code PENELOPE. To compare the suitability of each treatment for an anterior, equatorial and posterior tumor location, cumulative dose-volume histograms for the tumors and structures at risk were calculated.

Results

Eccentric placements of the plaques, taking into account the inhomogeneities of the emitter map, can substantially reduce the dose delivered to structures at risk while maintaining the prescribed dose at the tumor apex.

Conclusions

The emitter map distribution of the plaque and the computerized tomography of the patient used in a Monte Carlo simulation allow an accurate determination of the plaque position with respect to the tumor with the potential to reduce the dose to sensitive structures.

Diagnostic accuracy of 18F-FDG PET/CT and MR imaging in patients with adenoid cystic carcinoma

Background

The aim of this study was to evaluate the value of 18F–FDG PET/CT (PET/CT) and MRI for local and/or whole-body restaging of adenoid cystic carcinoma of the head and neck (ACC).

Methods

Thirty-six patients with ACC underwent conventional MRI of the head and neck and a whole-body PET/CT and were analysed with regards to detection of a local tumor recurrence, lymph node or distant metastases. A consensus interpretation of all available imaging data was used as reference standard. Sensitivity, specificity, diagnostic accuracy, positive and negative predictive values were calculated for MRI and PET/CT.

Results

The sensitivity of PET/CT and MRI was 96% (89%), specificity 89% (89%), PPV 96% (96%), NPV 89% (73%) and accuracy 94% (89%) for detection of local tumors. Additionally, PET/CT revealed lymph node metastases in one patient and distant metastases in 9/36 patients. In three patients secondary primaries were found.

Conclusions

Whole-body PET/CT in addition to MRI of the head and neck improves detection of local tumour and metastastic spread in ACC.

Dose Distributions and Treatment Margins in Ocular Brachytherapy with 106Ru Eye Plaques

Brachytherapy with ¹⁰⁶Ru eye plaques is the most common treatment modality for small to medium-sized uveal melanomas in Europe. So far, no standardized or widely accepted dose prescription protocol for the irradiation of intraocular tumors with ¹⁰⁶Ru eye plaques has been defined. For ¹²⁵I plaques, the minimum dose required for tumor control should be at least 85 Gy. Concerning ¹⁰⁶Ru plaques, the dose prescriptions at the University Hospital of Essen foresees minimum doses of 700 Gy to the tumor base and 130 Gy to the tumor apex. These dose prescriptions are expected to ensure sufficient treatment margins. We apply these dose prescriptions to different eye plaque types and tumor sizes and discuss the resulting treatment margins. These investigations are based on Monte Carlo simulations of dose distributions of 3 different eye plaque types. The treatment margin in apical direction has an expansion of at least 0.8 mm for all investigated eye plaques. For symmetrically formed eye plaques, the treatment margin at the base of the tumor goes beyond the visible edge of the plaque. This study focuses on the shape of 85-Gy isodose lines and on treatment margins for different eye plaque types and tumor sizes and shall help exchange knowledge for ocular brachytherapy.

Monte Carlo Estimation of Absorbed Dose Distributions Obtained from Heterogeneous 106Ru Eye Plaques

BACKGROUND

The distribution of the emitter substance in ¹⁰⁶Ru eye plaques is usually assumed to be homogeneous for treatment planning purposes. However, this distribution is never homogeneous, and it widely differs from plaque to plaque due to manufacturing factors.

METHODS

By Monte Carlo simulation of radiation transport, we study the absorbed dose distribution obtained from the specific CCA1364 and CCB1256 ¹⁰⁶Ru plaques, whose actual emitter distributions were measured. The idealized, homogeneous CCA and CCB plaques are also simulated.

RESULTS

The largest discrepancy in depth dose distribution observed between the heterogeneous and the homogeneous plaques was 7.9 and 23.7% for the CCA and CCB plaques, respectively. In terms of isodose lines, the line referring to 100% of the reference dose penetrates 0.2 and 1.8 mm deeper in the case of heterogeneous CCA and CCB plaques, respectively, with respect to the homogeneous counterpart.

CONCLUSIONS

The observed differences in absorbed dose distributions obtained from heterogeneous and homogeneous plaques are clinically irrelevant if the plaques are used with a lateral safety margin of at least 2 mm. However, these differences may be relevant if the plaques are used in eccentric positioning.

Validation of Blood Volume Fraction Quantification with 3D Gradient Echo Dynamic Contrast-Enhanced Magnetic Resonance Imaging in Porcine Skeletal Muscle

The purpose of this study was to assess the accuracy of fractional blood volume (v_b) estimates in low-perfused and low-vascularized tissue using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The results of different MRI methods were compared with histology to evaluate the accuracy of these methods under clinical conditions. v_b was estimated by DCE-MRI using a 3D gradient echo sequence with k-space undersampling in five muscle groups in the hind leg of 9 female pigs. Two gadolinium-based contrast agents (CA) were used: a rapidly extravasating, extracellular, gadolinium-based, low-molecular-weight contrast agent (LMCA, gadoterate meglumine) and an extracellular, gadolinium-based, albumin-binding, slowly extravasating blood pool contrast agent (BPCA, gadofosveset trisodium). LMCA data were evaluated using the extended Tofts model (ETM) and the two-compartment exchange model (2CXM). The images acquired with administration of the BPCA were used to evaluate the accuracy of v_b estimation with a bolus deconvolution technique (BD) and a method we call equilibrium MRI (EqMRI). The latter calculates the ratio of the magnitude of the relaxation rate change in the tissue curve at an approximate equilibrium state to the height of the same area of the arterial input function (AIF). Immunohistochemical staining with isolectin was used to label endothelium. A light microscope was used to estimate the fractional vascular area by relating the vascular region to the total tissue region (immunohistochemical vessel staining, IHVS). In addition, the percentage fraction of vascular volume was determined by multiplying the microvascular density (MVD) with the average estimated capillary lumen, π(d2)2, where d = 8μm is the assumed capillary diameter (microvascular density estimation, MVDE). Except for ETM values, highly significant correlations were found between most of the MRI methods investigated. In the cranial thigh, for example, the v_b medians (interquartile range, IQRs) of IHVS, MVDE, BD, EqMRI, 2CXM and ETM were v_b = 0.7(0.3)%, 1.1(0.4)%, 1.1(0.4)%, 1.4(0.3)%, 1.2(1.8)% and 0.1(0.2)%, respectively. Variances, expressed by the difference between third and first quartiles (IQR) were highest for the 2CXM for all muscle groups. High correlations between the values in four muscle groups—medial, cranial, lateral thigh and lower leg - estimated with MRI and histology were found between BD and EqMRI, MVDE and 2CXM and IHVS and ETM. Except for the ETM, no significant differences between the v_b medians of all MRI methods were revealed with the Wilcoxon rank sum test. The same holds for all muscle regions using the 2CXM and MVDE. Except for cranial thigh muscle, no significant difference was found between EqMRI and MVDE. And except for the cranial thigh and the lower leg muscle, there was also no significant difference between the v_b medians of BD and MVDE. Overall, there was good v_b agreement between histology and the BPCA MRI methods and the 2CXM LMCA approach with the exception of the ETM method. Although LMCA models have the advantage of providing excellent curve fits and can in principle determine more physiological parameters than BPCA methods, they yield more inaccurate results.

In Vivo Visualization of Prostate-Specific Membrane Antigen in Adenoid Cystic Carcinoma of the Salivary Gland

As the prostate-specific membrane antigen (PSMA) is overexpressed in the neovasculature of several malignancies, it might serve as a target in oncology. Ga-PSMA PET/CT and PET/MRI were performed in a female who developed pulmonary metastases from an adenoid cystic carcinoma of the right sublingual salivary gland after incomplete resection of the primary tumor and radiotherapy. Uptake of Ga-PSMA in tumors was observed, indicating PSMA expression. Moreover, a new cerebral metastasis was detected. Potentially, Ga-PSMA PET might be used for noninvasive assessment of adenoid cystic carcinoma to evaluate whether patients apply for PSMA-based radiotherapy when no further treatment options are available.

Incidence of second cancers after radiotherapy and systemic chemotherapy in heritable retinoblastoma survivors: A report from the German reference center

BACKGROUND

Survivors of heritable retinoblastoma carry a high risk to develop second cancers. Eye-preserving radiotherapy raises this risk, while the impact of chemotherapy remains less defined.

PROCEDURE

This population-based study characterizes the impact of all treatment modalities on second cancers incidence and type after retinoblastoma treatment in Germany. Data on second cancer incidence in 648 patients with heritable retinoblastoma treated between 1940 and 2008 at the German national reference center for retinoblastoma were analyzed to identify associations with treatment.

RESULTS

The cumulative incidence ratio (per 1,000 person years) of second cancers was 8.6 (95% confidence interval 7.0-10.4). Second cancer incidence was influenced by type of retinoblastoma treatment but not by the year of diagnosis or by sex. Radiotherapy and systemic chemotherapy increased the incidence of second cancers (by 3.0- and 1.8-fold, respectively). While radiotherapy was specifically associated with second cancers arising within the periorbital region in the previously irradiated field, chemotherapy was the strongest risk factor for second cancers in other localizations. Soft tissue sarcomas and osteosarcomas were the most prevalent second cancers (standardized incidence ratio 179.35 compared to the German population).

CONCLUSIONS

Second cancers remain a major concern in heritable retinoblastoma survivors. Consistent with previous reports, radiotherapy increased second cancer incidence and influenced type and localization. However, chemotherapy was the strongest risk factor for second malignancies outside the periorbital region. Our results provide screening priorities during life-long oncological follow-up based on the curative therapy the patient has received and emphasize the need for less-detrimental therapies for children with heritable retinoblastoma.

[Operative therapy and irradiation of conjunctival melanoma]

BACKGROUND

Radiotherapy of conjunctival melanoma has gained in importance in recent years compared to less invasive therapeutic approaches. This is due to the high recurrence rates achieved by omitting adjuvant therapy and to the increasing availability of suitable radiotherapeutic methods, so that tumors formerly not amenable to organ-preserving therapy can now be treated.

OBJECTIVE

This article presents the current radiotherapeutic options for conjunctival melanoma. The aim is to describe the diagnostic and therapeutic strategies and the course of therapy of malignant conjunctival melanoma. It is the authors' intention to justify the necessity of the adjuvant therapy of conjunctival melanoma and to emphasize the need for interdisciplinary cooperation during the course of tumor therapy.

METHODS

The article is based on results published in the literature as well as on data collected and experience gained in our centre.

Identification and Tumour-Binding Properties of a Peptide with High Affinity to the Disialoganglioside GD2

Neuroectodermal tumours are characterized by aberrant processing of disialogangliosides concomitant with high expression of GD2 or GD3 on cell surfaces. Antibodies targeting GD2 are already in clinical use for therapy of neuroblastoma, a solid tumour of early childhood. Here, we set out to identify peptides with high affinity to human disialoganglioside GD2. To this end, we performed a combined in vivo and in vitro screen using a recombinant phage displayed peptide library. We isolated a phage displaying the peptide sequence WHWRLPS that specifically binds to the human disialoganglioside GD2. Binding specificity was confirmed by mutational scanning and by comparative analyses using structurally related disialogangliosides. In vivo, significant enrichment of phage binding to xenografts of human neuroblastoma cells in mice was observed. Tumour-specific phage accumulation could be blocked by intravenous coinjection of the corresponding peptide. Comparative pharmacokinetic analyses revealed higher specific accumulation of 68Ga-labelled GD2-binding peptide compared to 111In-labelled peptide in xenografts of human neuroblastoma. In contrast to 124I-MIBG, which is currently evaluated as a neuroblastoma marker in PET/CT, 68Ga-labelled GD2-specific peptide spared the thyroid but was enriched in the kidneys, which could be partially blocked by infusion of amino acids.In summary, we here report on a novel tumour-homing peptide that specifically binds to the disialoganglioside GD2, accumulates in xenografts of neuroblastoma cells in mice and bears the potential for tumour detection using PET/CT. Thus, this peptide may serve as a new scaffold for diagnosing GD2-positive tumours of neuroectodermal origin.

Pediatric Survivors of Retinoblastoma Are at Risk for Altered Bone Metabolism After Chemotherapy Treatment Early in Life

Survivors of childhood cancer frequently suffer from endocrine late effects, which are, at least partly, attributed to toxic effects of chemotherapy. Treatment of retinoblastoma typically involves chemotherapy at a very young age. The authors conducted a cross-sectional study to assess bone health in a pediatric cohort of 33 survivors of retinoblastoma (mean age: 4.4 years) who had undergone chemotherapy treatment at an especially young age (mean age: 0.76 years). Of these patients, 14 had unilateral and 19 bilateral retinoblastoma. Polychemotherapy consisted of treatment with cyclophosphamide, etoposide, vincristine, and carboplatin. Ten patients had undergone external beam radiotherapy. Clinical and biochemical parameters of growth, pubertal development, and bone health were obtained. A vitamin D deficiency was found in 51.7% of the patients, and 13.7% of patients displayed severe vitamin D deficiency. Secondary hyperparathyroidism and altered readings for bone formation or resorption markers were present in 15%. Nine percent reported bone pain or experienced fractures of the long bones after primary diagnosis. No difference between children with bilateral and unilateral disease or irradiated versus nonirradiated children was observed. The parameters of thyroid function, growth, and pubertal development were within age-appropriate norms in almost all children. In conclusion, altered parameters of bone health can be present in survivors of retinoblastoma at a young age and warrant regular follow-up in these children. The endocrine hypothalamic-pituitary axes, however, were not impaired at this early age in this group of survivors of retinoblastoma.

How Eye-Preserving Therapy Affects Long-Term Overall Survival in Heritable Retinoblastoma Survivors

Purpose

Intraocular retinoblastoma is curable, but survivors with a heritable predisposition are at high risk for second malignancies. Because second malignancies are associated with high mortality, prognostic factors for second malignancy influence long-term overall survival. This study investigates the impact of all types of eye-preserving therapies on long-term survival in the complete German cohort of patients with heritable retinoblastoma.

Patients and Methods

Overall survival, disease staging using international scales, time period of diagnosis, and treatment type were analyzed in the 633 German children treated at the national reference center for heritable retinoblastoma.

Results

The 5-year overall survival of children diagnosed in Germany with heritable retinoblastoma between 1940 and 2008 was 93.2% (95% CI, 91.2% to 95.1%), but long-term mortality was increased compared with patients with nonheritable disease. Overall survival correlated with tumor staging, and 92% of patients were diagnosed with a favorable tumor stage (International Retinoblastoma Staging System stage 0 or I). Despite a 5-year overall survival of 97.4% (95% CI, 96.0% to 98.8%) in patients with stage 0 or I, only 79.5% (95% CI, 74.2% to 84.8%) of these patients survived 40 years after diagnosis. Long-term overall survival was reduced in children treated with eye-preserving radiotherapy compared with enucleation alone, and adding chemotherapy aggravated this effect.

Conclusion

The benefits of preserving vision must be balanced with the impact of eye-preserving treatments on long-term survival in heritable retinoblastoma, and the genetic background of the patient influences choice of eye-preserving treatment. Germline RB1 genetic analysis is important to identify heritable retinoblastoma among unilateral retinoblastoma cases. Eye-preserving radiotherapy should be carefully considered in patients with germline RB1 mutations. Life-long oncologic follow-up is crucial for all retinoblastoma survivors, and less detrimental eye-preserving therapies must be developed.

[Malignant tumours of the eye: Epidemiology, diagnostic methods and radiotherapy]

Malignant tumours of the eye are not common, barely representing 1 % of all cancers. This article aims to summarise, for each of the main eye malignant diseases, aspects of epidemiology, diagnostic methods and treatments, with a focus on radiation therapy techniques. The studied tumours are: eye metastasis, intraocular and ocular adnexal lymphomas, uveal melanomas, malignant tumours of the conjunctive, of the lids, and retinoblastomas. The last chapter outlines ocular complications of radiation therapy and their management.

Pediatric second primary malignancies after retinoblastoma treatment

BACKGROUND

Children with retinoblastoma carry a high risk to develop second primary malignancies in childhood and adolescence. This study characterizes the type of pediatric second primary malignancies after retinoblastoma treatment and investigates the impact of different treatment strategies and prognostic factors at presentation.

PROCEDURE

All national patients treated for retinoblastoma at the German referral center with a current age of 6-27 years were invited to participate in a study to characterize late effects.

RESULTS

Data on pediatric second primary malignancies were recorded from 488 patients. Ten developed a malignancy before the age of 18 years. For children with heterozygous oncogenic RB1 alteration (heritable retinoblastoma), the cumulative incidence to develop a second malignancy at the age of 10 years was 5.2% (95% CI 1.7; 8.7%). This results in an elevated risk for sarcoma (n = 4) (SIR 147.98; 95% CI 39.81; 378.87) and leukemia (n = 4) (SIR 41.38; 95% CI 11.13; 105.95). Neither the functional type of the RB1 alteration nor its origin showed a significant impact. Treatment modality influenced incidence, latency, and type of malignancy. Previous radiotherapy increased the risk for solid tumors and 3 of 91 children developed acute leukemia after chemotherapy. However, 2 of 10 malignancies were diagnosed in patients with heritable retinoblastoma but without previous chemotherapy or external beam radiotherapy.

CONCLUSIONS

Screening for second primary malignancy is an important part of pediatric oncological follow-up in patients with heritable retinoblastoma. For patients with sporadic unilateral retinoblastoma, genetic information influences treatment decisions and allows tailoring of follow-up schedules.

A geometrical model for the Monte Carlo simulation of the TrueBeam linac

Monte Carlo simulation of linear accelerators (linacs) depends on the accurate geometrical description of the linac head. The geometry of the Varian TrueBeam linac is not available to researchers. Instead, the company distributes phase-space files of the flattening-filter-free (FFF) beams tallied at a plane located just upstream of the jaws. Yet, Monte Carlo simulations based on third-party tallied phase spaces are subject to limitations. In this work, an experimentally based geometry developed for the simulation of the FFF beams of the Varian TrueBeam linac is presented. The Monte Carlo geometrical model of the TrueBeam linac uses information provided by Varian that reveals large similarities between the TrueBeam machine and the Clinac 2100 downstream of the jaws. Thus, the upper part of the TrueBeam linac was modeled by introducing modifications to the Varian Clinac 2100 linac geometry. The most important of these modifications is the replacement of the standard flattening filters by ad hoc thin filters. These filters were modeled by comparing dose measurements and simulations. The experimental dose profiles for the 6 MV and 10 MV FFF beams were obtained from the Varian Golden Data Set and from in-house measurements performed with a diode detector for radiation fields ranging from 3  ×  3 to 40  ×  40 cm(2) at depths of maximum dose of 5 and 10 cm. Indicators of agreement between the experimental data and the simulation results obtained with the proposed geometrical model were the dose differences, the root-mean-square error and the gamma index. The same comparisons were performed for dose profiles obtained from Monte Carlo simulations using the phase-space files distributed by Varian for the TrueBeam linac as the sources of particles. Results of comparisons show a good agreement of the dose for the ansatz geometry similar to that obtained for the simulations with the TrueBeam phase-space files for all fields and depths considered, except for the 40  ×  40 cm(2) field where the ansatz geometry was able to reproduce the measured dose more accurately. Our approach overcomes some of the limitations of using the Varian phase-space files. It makes it possible to: (i) adapt the initial beam parameters to match measured dose profiles; (ii) reduce the statistical uncertainty to arbitrarily low values; and (iii) assess systematic uncertainties (type B) by using different Monte Carlo codes. One limitation of using phase-space files that is retained in our model is the impossibility of performing accurate absolute dosimetry simulations because the geometrical description of the TrueBeam ionization chamber remains unknown.

[Molecular approaches to systemic therapy of adenoid cystic carcinoma of the head and neck area]

The adenoid cystic carcinoma (ACC) is a neurotropic salivary gland tumor with a high blood-borne metastasis tendency. The treatment of choice for localized disease consists of radical surgical resection and, depending on resection status, adjuvant radiotherapy. Due to the high recurrence rate with limited local therapeutic options and frequent occurrence of distant metastases, one is confronted inevitably with the search for an adequate systemic therapy. ACC shows little response to a variety of chemotherapeutic agents, partial or complete remissions are extremely rare. Beside classical chemotherapies, immunotherapeutics and targeted therapies with more favorable side effect profiles were tested in trials, but due to the small number of patients, a definitive statement on the effectiveness can be hardly made. This results in the need for prospective multicenter studies that allow clear recommendations for systemic therapy of the tumor. The present paper gives an overview of the sub-cellular and genetic characteristics of ACC, which represent possible targets for systemic therapies and have partly already been included in running clinical trials.

An indirect in vivo dosimetry system for ocular proton therapy

Secondary radiation, particularly neutron radiation, is a cause of concern in proton therapy. However, one can take advantage of its presence by using it to retrieve useful information on the primary proton beam. At the Centre Antoine Lacassagne the secondary radiation in the treatment room has been studied in function of the beam modulation. A strong correlation was found between the secondary ambient dose equivalent per proton dose H*(10)/D and proton dose rate D/MU. A large volume ionisation chamber fixed on the wall at 2.5 m from the nozzle was used with an in-house computer interface to retrieve the value of D/MU derived from the measurement of photon H*(10) integrated over treatment time, using the correlation curve. This system enables the verification of D and D/MU to be made independently of the monitoring of the primary beam and represents a first step towards an alternative in vivo dosimetry in proton therapy.

Monte Carlo Simulation of the Treatment of Eye Tumors with (106)Ru Plaques: A Study on Maximum Tumor Height and Eccentric Placement

BACKGROUND/AIMS

Ruthenium plaques are used for the treatment of ocular tumors. There is, however, a controversy regarding the maximum treatable tumor height. Some advocate eccentric plaque placement, without a posterior safety margin, to avoid collateral damage to the fovea and optic disc, but this has raised concerns about marginal tumor recurrence. There is a need for quantitative information on the spatial absorbed dose distribution in the tumor and adjacent tissues. We have overcome this obstacle using an approach based on Monte Carlo simulation of radiation transport.

METHODS

CCA and CCB (106)Ru plaques were modeled and their geometry embedded in a computerized tomography scan of the eye of a patient. Different tumor sizes and locations were simulated with the general-purpose Monte Carlo code PENELOPE.

RESULTS

Cumulative dose-volume histograms were obtained for the tumors and the tissues at risk considered. Plots of isodose lines for both plaques were obtained in a computerized tomography study.

CONCLUSIONS

Ruthenium eye plaques are an adequate treatment option for tumors up to around 5 mm in height. According to our results, assuming a correct placement of the plaque, a tumor of 6.5 mm apical height is about the maximum size that can be treated safely with the large CCB plaque.

Monte Carlo study for designing a dedicated "D"-shaped collimator used in the external beam radiotherapy of retinoblastoma patients

PURPOSE

Retinoblastoma is the most common intraocular malignancy in the early childhood. Patients treated with external beam radiotherapy respond very well to the treatment. However, owing to the genotype of children suffering hereditary retinoblastoma, the risk of secondary radio-induced malignancies is high. The University Hospital of Essen has successfully treated these patients on a daily basis during nearly 30 years using a dedicated "D"-shaped collimator. The use of this collimator that delivers a highly conformed small radiation field, gives very good results in the control of the primary tumor as well as in preserving visual function, while it avoids the devastating side effects of deformation of midface bones. The purpose of the present paper is to propose a modified version of the "D"-shaped collimator that reduces even further the irradiation field with the scope to reduce as well the risk of radio-induced secondary malignancies. Concurrently, the new dedicated "D"-shaped collimator must be easier to build and at the same time produces dose distributions that only differ on the field size with respect to the dose distributions obtained by the current collimator in use. The scope of the former requirement is to facilitate the employment of the authors' irradiation technique both at the authors' and at other hospitals. The fulfillment of the latter allows the authors to continue using the clinical experience gained in more than 30 years.

METHODS

The Monte Carlo code PENELOPE was used to study the effect that the different structural elements of the dedicated "D"-shaped collimator have on the absorbed dose distribution. To perform this study, the radiation transport through a Varian Clinac 2100 C/D operating at 6 MV was simulated in order to tally phase-space files which were then used as radiation sources to simulate the considered collimators and the subsequent dose distributions. With the knowledge gained in that study, a new, simpler, "D"-shaped collimator is proposed.

RESULTS

The proposed collimator delivers a dose distribution which is 2.4 cm wide along the inferior-superior direction of the eyeball. This width is 0.3 cm narrower than that of the dose distribution obtained with the collimator currently in clinical use. The other relevant characteristics of the dose distribution obtained with the new collimator, namely, depth doses at clinically relevant positions, penumbrae width, and shape of the lateral profiles, are statistically compatible with the results obtained for the collimator currently in use.

CONCLUSIONS

The smaller field size delivered by the proposed collimator still fully covers the planning target volume with at least 95% of the maximum dose at a depth of 2 cm and provides a safety margin of 0.2 cm, so ensuring an adequate treatment while reducing the irradiated volume.

Quantification of dose perturbations induced by external and internal accessories in ocular proton therapy and evaluation of their dosimetric impact

PURPOSE

Proton scattering on beam shaping devices and protons slowing down on media with different densities within the treatment volume may produce dose perturbations and range variations that are not predicted by treatment planning systems. The aim of this work was to assess the dosimetric impact of elements present in ocular proton therapy treatments that may disturb the prescribed treatment plan. Both distal beam shaping devices and intraocular elements were considered.

METHODS

A wedge filter, tantalum fiducial marker, hemispherical compensator, two intraocular endotamponades (densities 0.97 and 1.92 g cm(-3)) and an intraocular eye lens (IOL) were considered in the study. For these elements, longitudinal dose distributions were measured and∕or calculated in water in beam alignment for a clinical spread-out Bragg peak. Under the same conditions, the unperturbed dose distributions were similarly measured and∕or calculated in the absence of the element. The dosimetric impact was assessed by comparison of unperturbed and perturbed dose distributions. Measurements and calculations were carried out with two methods. Measurements are based on EBT3 films with dedicated software, which makes use of a calibration curve and correction for the quenching effect. Calculations are based on the Monte Carlo (MC) code MCNPX and reproduce the experimental conditions. Both dose maps are obtained with a resolution of 300 dpi.

RESULTS

The degree of disturbance of distal beam shaping devices is low for the wedge filter (2% overdose ripple all along the central axis) and moderate for the hemispherical compensator (two bands of variable overdose of up to 10% downstream the compensator lateral edges and -5% underdose on the plateau at off-axis distance of 5 cm). Tantalum clips produce important dose shadows (-20% behind the clip parallel to the beam and range reduction of 1.1 mm) and bands of overdose (15%). The presence of endotamponades modifies the dose distribution very significantly (-5% underdose on the plateau and 3 mm range prolongation for the tamponade with density 0.97 g cm(-3) and -15% underdose on plateau and 8 mm range reduction for that with density 1.92 g cm(-3)). No dose perturbations were found for the IOL. The high performance of EBT3 film and MC tools used was confirmed and good agreement was found between them (percentage of pixels passing the gamma test >87%).

CONCLUSIONS

The degree of disturbance by external beam shaping devices remains low in ocular proton therapy and can be reduced by bringing accessories closer to the eye. Tantalum fiducial markers must be located in such a way that dose perturbation is not projected on the tumor. The treatment of patients with intraocular endotamponades must be carefully managed. It is fundamental that radiation oncologists and medical physicists are informed about the presence of such substances prior to the treatment.

Vascular and nerval damage after intraoperative radiation therapy of the liver hilum in a large animal model

It has been demonstrated that intraoperative radiotherapy is a therapeutic option for patients suffering from perihilar cholangiocarcinoma. Aim of our study was to investigate vascular and nerve damages after irradiation of the liver hilum in a pig model. Twenty-four pigs underwent central bile duct resection followed by biliodigestive anastomosis. Nine pigs underwent this surgical procedure alone (group 1). Ten pigs were treated with additional intraoperative radiation therapy (IORT) of 20Gy to the liver hilum (group 2). And five pigs received operation and IORT with 40Gy to the area of anastomosis (group 3). Six weeks after operation and treatment the animals were sacrificed and histopathological examination was performed. Histology showed no vascular or nerve damage in non-irradiated perihilar tissue. Significant changes of nerve structures occurred, as well as vascular damage in large and even more in small hilar arteries in the irradiated neighboring liver tissue. In detail for small hilar arteries: intima proliferation (p ≤ .0001), endothelial swelling (p ≤ .0001), fibrinoid arterial wall necrosis (p ≤ .0001), and arterial thrombosis (p = .0079) were detected. Venous vessels did not show significant dose dependant cell damage. Overall, 20Gy as a single dose application during operation showed similar damage to vessels and nerves compared to 40Gy. A radiation dosage of 20Gy seems to be sufficient to induce necrosis due to vascular and nerve damage in potential malignant liver tissue with acceptable damage to surrounding tissue. Perineural invaded tumor cells might be diminished due to IORT.

[Diagnosis and treatment of retinoblastoma: current strategies for effective tumour control and preservation of vision]

There are approximately 40 new cases of retinoblastoma in Germany per year. Children in whom the tumour is detected when still intraocular have an excellent overall survival rate (> 95%). However, the prognosis of metastasised retinoblastoma remains poor. About 40% of retinoblastoma patients have tumours in both eyes. For these children in particular it is important to save the eye and visual function as much as possible. There are several options for conservative treatment of localised retinoblastoma including laser coagulation, thermotherapy, cryotherapy, brachytherapy and chemotherapy. In recent years, systemic chemotherapy has become the established standard for primary treatment of intraocular retinoblastoma. In case series, intra-arterial, intravitreal and periocular applications of chemotherapy were also shown to be effective in treating intraocular retinoblastoma. Genetic testing is an integral part of the routine diagnostics of all patients. Mutation analysis of tumour material is invaluable for identification of somatic mutations including mutational mosaicism. Genetic testing also identifies children with heritable retinoblastoma, which represent 50% of cases. These children also have a predisposition for the development of tumours outside of the eye (second primary neoplasm). To adequately address these and other late effects in survivors of retinoblastoma, a multidisciplinary approach is needed that optimises therapy and long-term follow-up. Upcoming multicentre clinical trials will evaluate treatment concepts for localised and metastasised retinoblastoma to improve survival rates and quality of life of children with retinoblastoma. This article was translated and modified and was primarily published in Klin Padiatr 2012; 224: 339-347.