Orbital growth retardation in retinoblastoma survivors: work in progress

Orbital Development in Children with Retinoblastoma: An Imaging-Based Study

PURPOSE

To examine whether children treated for Retinoblastoma (Rb) have impaired orbital development.

METHODS

A retrospective case series was performed among children with Rb treated at a single medical center from 2004 to 2020. Orbital volumes and measurements were assessed by 3-dimensional image processing software. The main outcome measures were differences in orbital growth between Rb and non-Rb eyes assessed at last follow-up.

RESULTS

Among 44 patients included (mean age 16.09 ± 18.01 months), a positive correlation between age and orbital volume was observed only in the uninvolved, healthy eyes (p = .03). In unilateral cases, orbital growth in the horizontal, vertical, and depth planes was smaller on the affected side compared to the healthy eyes (p < .05). Orbits that underwent enucleation showed decreased growth over time compared to those treated conservatively (p = .017).

CONCLUSIONS

Orbital growth rate is slower in the orbits of children treated for Rb compared to healthy orbits. Enucleation negatively affects orbital growth.

Impact of enucleation on adult retinoblastoma survivors' quality of life: A qualitative study of survivors' perspectives

OBJECTIVES

Retinoblastoma is the most common primary intraocular tumor of childhood with >95% survival rates in the US. Traditional therapy for retinoblastoma often included enucleation (removal of the eye). While much is known about the visual, physical, and cognitive ramifications of enucleation, data are lacking about survivors' perception of how this treatment impacts overall quality of life.

METHODS

Qualitative analysis of an open-ended response describing how much the removal of an eye had affected retinoblastoma survivors' lives and in what ways in free text, narrative form.

RESULTS

Four hundred and four retinoblastoma survivors who had undergone enucleation (bilateral disease = 214; 52% female; mean age = 44, SD = 11) completed the survey. Survivors reported physical problems (n = 205, 50.7%), intrapersonal problems (n = 77, 19.1%), social and relational problems (n = 98, 24.3%), and affective problems (n = 34, 8.4%) at a mean of 42 years after diagnosis. Three key themes emerged from survivors' responses; specifically, they (1) continue to report physical and intrapersonal struggles with appearance and related self-consciousness due to appearance; (2) have multiple social and relational problems, with teasing and bullying being prominent problems; and (3) reported utilization of active coping strategies, including developing more acceptance and learning compensatory skills around activities of daily living.

SIGNIFICANCE OF RESULTS

This study suggests that adult retinoblastoma survivors treated with enucleation continue to struggle with a unique set of psychosocial problems. Future interventions can be designed to teach survivors more active coping skills (e.g., for appearance-related issues, vision-related issues, and teasing/bullying) to optimize survivors' long-term quality of life.

Primary orbital polymethylmethacrylate implant following primary enucleation for retinoblastoma: a study of 321 cases

Purpose: To evaluate the outcome of primary orbital polymethylmethacrylate (PMMA) implant following the primary enucleation for retinoblastoma. Methods: Retrospective study of 321 retinoblastoma patients who underwent unilateral enucleation and PMMA implant for retinoblastoma by myoconjunctival technique. Outcome measures included implant centration and extrusion. Results: The mean age at the time of enucleation of patients with retinoblastoma was 35 months (median, 30 months; range, <1 to 449 months). After primary enucleation, primary orbital PMMA implant was used in all cases. The mean diameter of implant was 18 mm (median, 18 mm; range, 12-20 mm) and the mean horizontal diameter of the socket conformer was 24 mm (median, 24 mm; range, 18 mm-26 mm). Post-enucleation and implant, seven (2%) patients underwent orbital external beam radiotherapy owing to microscopic extrascleral tumor extension or tumor infiltration of optic nerve transection. Over a mean follow-up period of 40 months (median, 34 months; range, 4-129 months), implant migration was noted in 28 (9%) patients, implant extrusion in 9 (3%), and implant exposure in 5 (2%), and contracted socket in 5 (2%) patients including grade 1 contraction in 3 (1%), grade 2 in 1 (<1%), and grade 4 in 1 (<1%) patient. Implant exchange for an improved prosthesis fit was performed in 4 (1%) cases. Stable customized ocular prosthesis was achieved in all but one patient. Conclusion: Primary orbital PMMA implant following primary enucleation for retinoblastoma is associated with minimal complications and provides acceptable cosmetic outcomes.

The effect of enucleation on orbital growth in patients with retinoblastoma

PURPOSE

To measure orbital volume using serial magnetic resonance imaging (MRI) scans to determine the effect of enucleation on orbital growth over time.

METHODS

The medical records of patients who underwent unilateral enucleation for retinoblastoma with a minimum of 2 MRIs were retrospectively reviewed. Orbital asymmetry was calculated using MRI measurements. Nonlinear and linear mixed effect regression models were used to predict the effect of age at time of enucleation on degree of orbital asymmetry.

RESULTS

A total of 27 patients were included (mean age at enucleation, 2 years; range, 2.5 months to 5 years). Age at scan (P = 0.046) and age at enucleation (P = 0.0006) were found to have a significant effect on orbital asymmetry. Change in orbital asymmetry over time was more pronounced after enucleation in children enucleated at <1 (P < 0.0001) or <2 years of age (P = 0.0109). Younger age at enucleation was associated with a greater degree of asymmetry over time, although this effect was extinguished for patients enucleated after the age of 3 years.

CONCLUSIONS

In patients with retinoblastoma, enucleation with orbital implant before 3 years of age has a significant effect on orbital volume asymmetry. After the age of 3, this effect appears to be less detrimental to the degree of orbital asymmetry.

Biphasic growth of orbital volume in Chinese children

Objective

The aim of this study was to map out the developmental curve of the orbital volume of Chinese children aged 1–15 years.

Methods

CT scanning was performed on 109 children and the orbital volume, interlateral orbital rim distance (IORD), and extent of exophthalmos were measured on the CT images and plotted against age.

Results

The development of the orbit structure followed a biphasic pattern. The first growth phase was before 3 years and the second growth phase was between 7 years and 12 years of age. The growth speed in the first phase was about 3 times that of the second one (first vs second phase: 2.28 cm³/year vs 0.67 cm³/year for orbital volume, 5.01 mm/year vs 1.57 mm/year for IORD, 1.29 mm/year vs 0.42 mm/year for the exophthalmos). During development, there was no significant difference between the left and right orbits. There was no significant difference between boys and girls before 12 years of age. However, after 12 years of age, boys had significantly larger orbital volumes (22.16±2.28 cm³/year vs 18.57±1.16 cm³/year, p<0.001) and a greater IORD (96.29±3.18 mm/year vs 91.00±4.54 mm/year, p<0.001) than girls.

Conclusions

In Chinese children, the development of orbital volume follows a biphasic pattern and a sex difference becomes significant after the age of 12 years.

Chronic medical conditions in adult survivors of retinoblastoma: Results of the Retinoblastoma Survivor Study

BACKGROUND

Limited data are available regarding long-term morbidity in adult survivors of retinoblastoma (Rb).

METHODS

The Retinoblastoma Survivor Study is a retrospective cohort of adult survivors of Rb diagnosed between 1932 and 1994. Participants completed a comprehensive questionnaire adapted from the Childhood Cancer Survivor Study surveys. Chronic conditions were classified using the National Cancer Institute's Common Terminology Criteria for Adverse Events (version 4.03). Multivariate Poisson regression was used to compare survivors of Rb with 2377 non-Rb controls, consisting of the Childhood Cancer Survivor Study sibling cohort and survivors with bilateral versus unilateral disease.

RESULTS

Survivors of Rb (53.6% with bilateral disease) and non-Rb controls had a mean age of 43.3 years (standard deviation, 11 years) and 37.6 years (SD, 8.6 years), respectively, at the time of study enrollment. At a median follow-up of 42 years (range, 15-75 years), 86.6% of survivors of Rb had at least 1 condition and 71.1% had a severe/life-threatening (grade 3-4) condition. The adjusted relative risk (RR) of a chronic condition in survivors compared with non-Rb controls was 1.4 (95% confidence interval [95% CI], 1.3-1.4; P<.01); for a grade 3 to 4 condition, the RR was 7.6 (95% CI, 6.4-8.9; P<.01). Survivors were at an excess risk regardless of laterality. After stratifying by laterality and excluding ocular conditions and second malignant neoplasms (SMNs), only those with bilateral disease were found to be at an increased risk of any nonocular, non-SMN condition (RR, 1.2; 95% CI, 1.1-1.2) and for grade 3 to 4 nonocular, non-SMN conditions (RR, 1.7; 95% CI, 1.2-2.5).

CONCLUSIONS

Survivors of Rb have an increased risk of chronic conditions compared with non-Rb controls. After excluding ocular conditions and SMNs, this excess risk was found to persist only for those with bilateral disease. Cancer 2016;122:773-781. © 2016 American Cancer Society.

Long-Term Outcomes of Group B Eyes in Patients with Retinoblastoma Treated with Short-Course Chemoreduction: Experience from Children's Hospital Los Angeles/University of Southern California

BACKGROUND/AIMS

Chemoreduction protocols for retinoblastoma vary widely across institutions. Herein, we compare a 3- versus 6-cycle chemotherapy approach for group B retinoblastoma.

METHODS

A nonrandomized, retrospective review of patients diagnosed with group B retinoblastoma from 1991-2011 at Children's Hospital Los Angeles was performed. A total of 72 eyes of 63 patients were analyzed. Mean follow-up time was 82 months (range 6-272 months). Main outcome measures were globe salvage and need for external beam radiation.

RESULTS

Forty-six patients (55 eyes) were treated upfront with 3 cycles of carboplatin, etoposide, and vincristine; 17 patients (17 eyes) received 6 cycles. Thirty-seven eyes (67%) in the 3-cycle group were cured with initial chemoreduction alone. An additional 10 eyes with persistent or recurrent tumors were rescued with 3 more cycles for a total salvage rate of 85% (47/55 eyes). In the 6-cycle group, 16 of 17 eyes (94%) avoided radiation and enucleation.

CONCLUSION

The initial recurrence rate was higher for the 3-cycle group (p = 0.03). However, eyes failing short-course chemoreduction were rescued with 3 additional cycles and achieved a similar overall event-free survival rate (p = 0.16). In our cohort, this short-course approach spared 63% (29/46) of patients with group B retinoblastoma the extra 3 cycles of systemic chemotherapy.

Bony orbital maldevelopment after enucleation

One common belief in ophthalmology is that enucleation at an early age will result in bony orbital maldevelopment and facial asymmetry. However, the age range in which enucleation is associated with risk of orbital maldevelopment and the extent of asymmetry remains controversial. In this study, patients who had undergone unilateral enucleation at different ages without orbital implantation were analysed to investigate bony orbital development after enucleation. A total of 87 Chinese adult patients were included. Their bony orbital volume and orbital aditus area were measured using three-dimensional reconstructive models based on patients' computer tomography scans. The ratio of the parameter values of the affected orbit to the unaffected orbit was calculated and described as the orbital symmetry index. The results showed that the bony orbit grew until approximately 18 years old. Enucleation after that age did not affect the orbit, whereas enucleation before that age led to significant orbital maldevelopment. The relative reduction ranged up to 20% in orbital volume and 17% in the orbital aditus area. The extent of orbital maldevelopment was correlated to the age of enucleation. The symmetry index of orbital volume = -0.0003x(2)  + 0.0159x + 0.8112 (x = the age of enucleation). The symmetry index of the orbital aditus area = -0.0002x(2)  + 0.0119x + 0.8504 (x = the age of enucleation). The regression formulae were used to predict the severity of orbital asymmetry after unilateral enucleation, and evaluate the necessity and efficacy of interventions following enucleation.

Recommendations for post-adaption care of an ocular prosthesis: A review

An ocular prosthesis must be maintained in a suitable state of cleanliness, fit and preservation. Otherwise its functioning may be compromised, leading to a variety of diseases. However, there is a lack of consensus on the care of such prostheses. This review assembles and attempts to update existing knowledge in this area and discusses the most appropriate care regimes.

Worldwide enucleation techniques and materials for treatment of retinoblastoma: an international survey

Purpose

To investigate the current practice of enucleation with or without orbital implant for retinoblastoma in countries across the world.

Methods

A digital survey identifying operation techniques and material used for orbital implants after enucleation in patients with retinoblastoma.

Results

We received a response of 58 surgeons in 32 different countries. A primary artificial implant is routinely inserted by 42 (72.4%) surgeons. Ten (17.2%) surgeons leave the socket empty, three (5.2%) decide per case. Other surgeons insert a dermis fat graft as a standard primary implant (n=1), or fill the socket in a standard secondary procedure (n=2; one uses dermis fat grafts and one artificial implants). The choice for porous implants was more frequent than for non-porous implants: 27 (58.7%) and 15 (32.6%), respectively. Both porous and non-porous implant types are used by 4 (8.7%) surgeons. Twenty-five surgeons (54.3%) insert bare implants, 11 (23.9%) use separate wrappings, eight (17.4%) use implants with prefab wrapping and two insert implants with and without wrapping depending on type of implant. Attachment of the muscles to the wrapping or implant (at various locations) is done by 31 (53.4%) surgeons. Eleven (19.0%) use a myoconjunctival technique, nine (15.5%) suture the muscles to each other and seven (12.1%) do not reattach the muscles. Measures to improve volume are implant exchange at an older age (n=4), the use of Restylane SQ (n=1) and osmotic expanders (n=1). Pegging is done by two surgeons.

Conclusion

No (worldwide) consensus exists about the use of material and techniques for enucleation for the treatment of retinoblastoma. Considerations for the use of different techniques are discussed.

Dermis fat graft implantation after unilateral enucleation for retinoblastoma in pediatric patients

PURPOSE

To evaluate the efficacy of dermis fat graft (DFG) as a primary implant technique in pediatric patients requiring unilateral enucleation due to retinoblastoma.

METHODS

A retrospective chart review of 14 consecutive pediatric patients who underwent dermis fat graft implantation after unilateral enucleation for retinoblastoma by 1 surgeon (E.A.S.) was performed to evaluate graft efficacy with regard to orbital volume growth and any associated morbidity. Patients who received chemotherapy or external beam radiation were excluded. Demographic information was recorded. Serial MRIs were used to measure orbital volumes to compare the surgical and contralateral orbits over time. The main outcome measure was the difference in bony orbital volume between enucleated and contralateral, uninvolved orbits. Mann-Whitney U test was used to compare orbital volume measurements between surgical and nonsurgical orbits. Correlation testing was performed to determine the effect of age, sex, and follow-up time on the orbital volume changes.

RESULTS

There was no statistical difference between the MRI volume measured for surgical and nonsurgical orbits over time. This was the case at all measured time points and for all ages and genders. All patients were under the age of 4 years at the time of surgery. The median difference in orbital volumes between surgical and nonsurgical orbits was -0.095 cm (range -1.26 to 1.01 cm; quartiles -0.32 to 0.07 cm; mean ± SD, -0.144 ± 0.0522 cm; 95% confidence interval, -0.247 to -0.0419 cm). The median follow-up time from surgery date to the most recent clinical examination was 38.5 months (range, 13 to 70 months; quartiles, 28.75 to 45.5 months; mean ± standard deviation [SD], 38.43 ± 17.21 months; 95% confidence interval, 29.41 to 47.45 months).

CONCLUSIONS

In pediatric patients below 4 years of age with unilateral retinoblastoma treated with enucleation and primary dermis fat graft implantation, there was no statistically significant difference in bony orbital volume between the surgical and nonsurgical orbits during the follow-up period.

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.

A multidisciplinary approach for ocular rehabilitation following surgical treatment of retinoblastoma: One year follow-up

Retinoblastoma is a highly malignant neoplasm. Most of the cases are usually advanced at the time of detection, requiring enucleation to salvage the child's life. Just treating the patient for cancer is not enough; the cosmetic rehabilitation of these patients is equally important and it should always be an integral part of their treatment, to help them re-integrate in the aesthetic conscious society. Rehabilitating such patients require a multidisciplinary approach involving the combined and timely efforts of an ophthalmologist, paediatric oncologist and a skilled maxillofacial prosthodontist. This paper presents a case of 3½-year-old girl who had enucleation of her right eye due to retinoblastoma along with chemotherapy and radiotherapy at the age of 3 years. The patient was recalled regularly for follow-up at 3 month intervals for ophthalmic examinations and she was rehabilitated cosmetically with customised ocular prosthesis during the various stages of her developmental growth.

A palliative approach for rehabilitation of a pediatric patient with retinoblastoma

Retinoblastoma is a highly malignant neoplasm. Most of the cases are usually far advanced at the time of detection, requiring enucleation to salvage the child's life. However, the cosmetic rehabilitation of these patients should always be an integral part of their treatment, which helps in their re-integration in the society. This paper presents a case of 5-year-old patient who had undergone enucleation of her left eye due to retinoblastoma. A multidisciplinary approach, including ophthalmologist, psychotherapist, and a prosthodontist, was adopted to meet her physical, psychological, functional, emotional, social, and cosmetic demands. The patient was rehabilitated cosmetically with precisely fabricated ocular prosthesis. An ocular prosthesis is a highly positive and non-invasive approach to improve the cosmetic appearance and psychological well-being of patient.

Long-term outcomes of Group D eyes in bilateral retinoblastoma patients treated with chemoreduction and low-dose IMRT salvage

BACKGROUND

To evaluate outcomes of Group D eyes of bilateral retinoblastoma patients treated with primary chemoreduction and external beam radiation as salvage.

PROCEDURE

Retrospective chart review of patients diagnosed with bilateral retinoblastoma and designated Group D in at least one eye from January 1, 2000 to December 31, 2009. Overall, 62 Group D eyes of 49 patients were included; 13 had bilateral Group D disease. Primary chemoreduction with vincristine, etoposide, and carboplatin with local consolidation was administered, followed by external beam radiation in the form of intensity-modulated radiation therapy (IMRT) as salvage for recurrent tumor. Primary outcome measure was globe salvage.

RESULTS

Of 62 Group D eyes, 7 were enucleated primarily; 55 were treated with systemic chemoreduction, and local therapy. Chemoreduction cured 26 of 55 eyes (47%). Recurrences were found in 29 eyes; 5 underwent enucleation and 24 were treated with IMRT at a dose of 24 Gy (2 eyes) or 36 Gy (22 eyes). Of the 24 irradiated eyes, 19 (79%) were salvaged and 5 required enucleation. Final visual acuity ranged from 20/20 to light perception with 10 eyes having 20/80 or better visual acuity. Average follow-up was 54.2 months.

CONCLUSION

Kaplan-Meier estimates of eye survival of Group D eyes in bilateral patients at 12 months is 82% (95% confidence interval [CI] 70.1-89.7%); at 60 months eye survival is estimated to be 68% (95% confidence interval [CI] 55.4-82.8%). Systemic treatment for retinoblastoma demonstrated a high rate of globe preservation with acceptable complications and many eyes retaining functional vision.

Retinoblastoma: an overview

Retinoblastoma, the most common intraocular malignancy of childhood arises due to mutation of the retinoblastoma gene on chromosome 13q14. In the hereditary setting this mutation is present in all germ line cells and can occur as early as during development; however it requires a mandatory second "hit" or mutation of the remaining allele for retinoblastoma to develop. The non-hereditary form arises from spontaneous mutation affecting both alleles in a somatic cell of the retina. The tumor may present with leucocoria or strabismus. The diagnosis is best made by an ophthalmologist who examines the patient under sedation. Although tissue biopsy is not routinely performed, imaging studies like ultrasound and MRI scan can serve as useful adjuncts to help in establishing the diagnosis and also aid in staging. Group A tumors are smaller than 3 mm while group B tumors are >3 mm or those located in the macula. Groups C and D tumors are associated with localized and diffuse vitreous seeds respectively. Group E tumors occupy >50% of the globe and are generally not salvagable. Despite the fact that great advances have been made in the treatment of retinoblastoma in the last two decades, a large number patients undergo procedures associated with significant morbidity such as enucleation. We recommend large multi institutional studies using newer therapeutic models and targeting novel pathways to improve the outcome in advanced stage retinoblastoma.

Abnormal orbital growth in children submitted to enucleation for retinoblastoma treatment

Enucleation is typically performed for the treatment of advanced retinoblastoma in children. After enucleation, the orbit undergoes abnormal development. In this study, orbital asymmetry was calculated using computed tomography measurements obtained from patients who experienced enucleation for unilateral retinoblastoma. Influence factors analyzed included: type of treatment, use of orbital implants, and patient's age at diagnosis. A total of 42 children underwent enucleation with a mean follow-up period of 4.8 years. For 28 patients, treatment included enucleation alone, 14 patients received enucleation plus radiation therapy. Thirty patients kept orbital implants long term. The mean orbital volume asymmetry for treated versus contralateral orbits was 16.8%. Mean asymmetry in orbital volume was greater for patients who underwent enucleation combined to radiation therapy (23.7% vs. 13.3%, P=0.05) and for patients without long-term maintenance of the prosthetic implants (29.3% vs. 11.8%, P<0.01). In conclusion, orbital volume is abnormally affected in children after enucleation of 1 eye for the treatment of retinoblastoma, and computed tomography can precisely quantify the asymmetry that develops. Orbital implants improve volumetric growth after enucleation, with 2-fold greater orbital asymmetry achieved without an implant.

Strategies to manage retinoblastoma in developing countries

Survival of retinoblastoma is >90% in developed countries but there are significant differences with developing countries in stage at presentation, available treatment options, family compliance, and survival. In low-income countries (LICs), children present with advanced disease, and the reasons are socioeconomic and cultural. In middle-income countries (MICs), survival rates are better (>70%), but there is a high prevalence of microscopically disseminated extraocular disease. Programs for eye preservation have been developed, but toxicity-related mortality is higher. Although effective treatment of microscopically extraocular disease improved the outcome, worldwide survival will be increased only by earlier diagnosis and better treatment adherence.

Bilateral conjunctival extranodal marginal zone B-cell lymphoma

Extranodal marginal zone B-cell lymphomas (EMZLs), while relatively common in adults, are rare entities in the pediatric population. A subclass of the typically aggressive non-Hodgkin lymphomas, the few reported pediatric cases indicate that, as in adults, these tumors tend to be indolent. We present a case of EMZL arising in the conjunctivae in a 9-year-old male with bilateral disease. The patient was treated with surgical excision alone and has remained disease-free 6 years after the operation.

Preliminary experience in treatment of papillary and macular retinoblastoma: evaluation of local control and local complications after treatment with linear accelerator-based stereotactic radiotherapy with micromultileaf collimator as second-line or salvage treatment after chemotherapy

PURPOSE

To determine the local control and complication rates for children with papillary and/or macular retinoblastoma progressing after chemotherapy and undergoing stereotactic radiotherapy (SRT) with a micromultileaf collimator.

METHODS AND MATERIALS

Between 2004 and 2008, 11 children (15 eyes) with macular and/or papillary retinoblastoma were treated with SRT. The mean age was 19 months (range, 2-111). Of the 15 eyes, 7, 6, and 2 were classified as International Classification of Intraocular Retinoblastoma Group B, C, and E, respectively. The delivered dose of SRT was 50.4 Gy in 28 fractions using a dedicated micromultileaf collimator linear accelerator.

RESULTS

The median follow-up was 20 months (range, 13-39). Local control was achieved in 13 eyes (87%). The actuarial 1- and 2-year local control rates were both 82%. SRT was well tolerated. Late adverse events were reported in 4 patients. Of the 4 patients, 2 had developed focal microangiopathy 20 months after SRT; 1 had developed a transient recurrence of retinal detachment; and 1 had developed bilateral cataracts. No optic neuropathy was observed.

CONCLUSIONS

Linear accelerator-based SRT for papillary and/or macular retinoblastoma in children resulted in excellent tumor control rates with acceptable toxicity. Additional research regarding SRT and its intrinsic organ-at-risk sparing capability is justified in the framework of prospective trials.

New developments in external beam radiotherapy for retinoblastoma: from lens to normal tissue-sparing techniques

Historically, retinoblastoma was treated with external beam radiotherapy (EBR) and for many years this was the accepted standard of care. With greater knowledge of radiation-induced morbidity and mortality, the trend over the past decade has shifted towards primary chemotherapy for most globe conservative treatments. Such a radical change in treatment modalities has restrained EBR to second-line and salvage indications with little consensus regarding dose, timing and techniques. New radiotherapy options now allow for more focused radiation to the globe with further sparing of adjacent structures in such a way that their role in the management of retinoblastoma need to be reappraised. In this perspective paper, first the historical techniques of using EBR primarily with linear accelerated photons are reviewed. Then modern approaches are described, such as stereotactic conformal radiotherapy using a micromultileaf collimator, and proton therapy using a fixed horizontal beam and tantalum localization, or a rotating ganthry with spot scanning. For the first time, to the authors' knowledge, the benefits of these new irradiation modalities over conventional EBR are illustrated with six successfully treated pilot cases. Finally, some guidelines are provided regarding indications to modern radiation therapy in patients requiring second-line or salvage treatment for intraocular retinoblastoma, as well as adjuvant therapy for orbital involvement.

Perspective on Orbital Enucleation Implants

The philosophy and design of orbital enucleation implants have evolved significantly over the past 50 years. Animal studies and improved imaging techniques have changed our understanding about the physiology and anatomy of the post-enucleation orbit. Changes in implant design and biomaterials have reduced complication rates. It is our impression that for many ophthalmic professionals in training, the rational behind the current thinking in implant design and biomaterials is unclear. This is in part related to the older literature on orbital enucleation implants, which is scattered and at times contradictory. This review aims to present the historical information in a coherent and concise form; provide evidence based review of changes in the practice patterns of enucleation; identify areas of continuing controversy; and highlight gaps in the scientific literature about orbital implants, in particular, the poor understanding of implant and prosthesis motility.

Proton radiation therapy for retinoblastoma: Comparison of various intraocular tumor locations and beam arrangements

PURPOSE

To study the optimization of proton beam arrangements for various intraocular tumor locations; and to correlate isodose distributions with various target and nontarget structures.

METHODS AND MATERIALS

We considered posterior-central, nasal, and temporal tumor locations, with straight, intrarotated, or extrarotated eye positions. Doses of 46 cobalt grey equivalent (CGE) to gross tumor volume (GTV) and 40 CGE to clinical target volume (CTV) (2 CGE per fraction) were assumed. Using three-dimensional planning, we compared isodose distributions for lateral, anterolateral oblique, and anteromedial oblique beams and dose-volume histograms of CTVs, GTVs, lens, lacrimal gland, bony orbit, and soft tissues.

RESULTS

All beam arrangements fully covered GTVs and CTVs with optimal lens sparing. Only 15% of orbital bone received doses > or =20 CGE with a lateral beam, with 20-26 CGE delivered to two of three growth centers. The anterolateral oblique approach with an intrarotated eye resulted in additional reduction of bony volume and exposure of only one growth center. No appreciable dose was delivered to the contralateral eye, brain tissue, or pituitary gland.

CONCLUSIONS

Proton therapy achieved homogeneous target coverage with true lens sparing. Doses to orbit structures, including bony growth centers, were minimized with different beam arrangements and eye positions. Proton therapy could reduce the risks of second malignancy and cosmetic and functional sequelae.