Radiotherapy of retinoblastoma. A review of 63 children treated with different irradiation techniques

Prognostic Factors for Eye Globe Salvage by External Beam Radiation Therapy for Resistant Intraocular Retinoblastoma

PURPOSE:

To analyse the prognostic factors for eye salvage for eyes with intra-ocular retinoblastoma (RB) that is resistant to systemic chemotherapy and focal therapy by external beam radiation therapy (EBRT).

METHODS:

A retrospective analysis of 28 eyes with intra-ocular RB that was resistant for systemic chemotherapy and focal consolidation therapy and received EBRT. Outcome measures included tumor stage at diagnosis, stage migration, type of tumor seeds, treatment modalities, eye globe salvage, metastasis, and survival.

RESULTS:

Most of the patients (83%) had bilateral RB, and 42% were females. All eyes were treated initially by combination of systemic chemotherapy and focal consolidation therapy. The dose of EBRT was 45 Gy. The mean follow-up was 6.5 years, and the overall eye globe salvage rate post EBRT was 46%: 67% (2/3) for group B, 71% (5/7) for group C, and 33% (6/18) for group D. Patient's gender, tumor site, laterality, and tumor stage at diagnosis were not significant prognostic factors (p> 0.05) for final outcome. The significant poor prognostic factors were tumor stage migration during systemic chemotherapy (p= 0.03) and presence of vitreous seeds at time of EBRT (p=0.001). Post EBRT complication rate was 68% (19/28) including; retinal detachment (3), vitreous hemorrhage (4), neovascular glaucoma (1), cataract (16), radiation retinopathy (2), and second malignancy (2).

CONCLUSION:

EBRT is an alternative for enucleation when RB is resistant to combined chemoreduction/focal consolidation therapy in absence in vitreous seeds. The known risks for EBRT are not justified for patients with unilateral RB and for those who have functional vision in the other eye.

The role of external beam radiation therapy for retinoblastoma after failure of combined chemoreduction and focal consolidation therapy

Purpose: To study the role of external beam radiation therapy (EBRT) for the treatment of retinoblastoma eyes that were not cured by combined systemic chemotherapy and focal consolidation therapy.Methods and Materials: A retrospective case series of 28 eyes for 24 retinoblastoma patients treated by EBRT after the failure of tumor controlled by chemotherapy and focal therapy. The main outcome measures included: international intraocular retinoblastoma classification stage (IIRC) and Reese Ellsworth (RE) stage, tumor seeding, treatment modalities, eye salvage, and survival.Results: The median age at diagnosis was 11 months. There were 14 (58%) males and 20 (83%) bilateral cases. All eyes were treated initially by systemic chemotherapy (range; 6-8 cycles). The dose of radiation used for all eyes was 45 Gray (Gy).The mean follow-up was 75months, and the overall eye salvage rate after EBRT was 13 (46%) eyes: 67% (2/3) for IIRC group B, 71% (5/7) for group C, and 33% (6/18) for group D eyes. Vitreous seeds and tumor stage migration during management by chemotherapy were the most important significant predictive factors for tumor control (p = .001 and 0.033, respectively).Conclusion: Eyes with retinoblastoma that failed chemotherapy followed by focal therapy were controlled with EBRT. However, the presence of vitreous seeds, stage migration during the course of chemotherapy, as well as good vision in the other eye may not justify the known risks of EBRT.

Lens Dose-Response Prediction Modeling and Cataract Incidence in Patients With Retinoblastoma After Lens-Sparing or Whole-Eye Radiation Therapy

PURPOSE

We retrospectively assessed the incidence of cataracts in patients with retinoblastoma (Rb) treated with either lens-sparing radiation therapy (LSRT) or whole-eye radiation therapy (WERT). A secondary aim of this study was to model the dose-response risk of cataract.

METHODS AND MATERIALS

We reviewed 65 patients with Rb treated with radiation therapy (RT) at Children's Hospital, Los Angeles from 1997 to 2015. Eyes that were enucleated before RT or lacked follow-up eye examinations were excluded. All patients underwent computed tomography simulation, and mean lens dose data were collected. Follow-up ophthalmologic examinations and intraocular lens implant history were reviewed for cataracts. The primary event-free survival (EFS) outcome was cataract development. Eyes without cataracts were censored on the last date of eye examination or post-RT enucleation, if applicable. Kaplan-Meier estimates were used to compare EFS outcomes, and dose response was projected with Cox regression and logistic regression models.

RESULTS

Sixty-one patients (94 eyes) were analyzed with a median follow-up of 51.8 months. For eyes treated with WERT, cataracts developed in 71.7% versus 35.3% for LSRT. Median EFS for WERT and LSRT were 20.8 and 67.9 months, respectively. Compared with WERT, a significant EFS benefit was demonstrated for LSRT (P < .001). Mean lens dose had a significant effect on cataracts in both Cox regression and logistic regression models (P < .01). The mean lens dose of 7 Gy was projected to have a 5-year cataract incidence of 20% and 25% with the logistic and Cox regression models, respectively.

CONCLUSIONS

We report the first clinical data demonstrating significantly improved EFS in patients with Rb treated with LSRT. Through lens dose-response modeling, we validate a mean lens dose threshold of 7 Gy to keep cataract risk below 25%. Although RT is used less often for Rb owing to advances in chemotherapy delivery options, these findings are relevant for refining lens dose constraints, particularly in children who have received radiation dose near the orbit.

Ocular and Orbital Complications following the Treatment of Retinoblastoma

Purpose

To investigate the ocular and orbital complications observed in children treated for retinoblastoma.

Methods

We retrospectively studied 73 children (39 boys, 34 girls) suffering from retinoblastoma. Thirty-six had bilateral tumor and 37 unilateral disease for a total of 109 eyes affected. The follow-up was 6–180 months (median 36 months). Enucleation was the most common initial treatment approach in the unilateral group, and radiotherapy (by external beam) was the most common initial therapy in the bilateral group. Cryotherapy, photocoagulation, brachytherapy and/or systemic chemotherapy were used as adjuvant treatments when necessary. Ocular complications were recorded at the follow-up examinations.

Results

Cataract developed in 20% of the irradiated eyes. The mean time from irradiation until development of cataract was 28.5 months (6–64 months). Radiation retinopathy developed in 12% and was first detected 11–72 months (mean 37 months) after irradiation therapy. Mild transient keratopathy was observed in all eyes undergoing irradiation, and xerophthalmia in one eye. Complications after enucleation included: marked discharge from the socket (11.0%), extrusion of the implant (9.6%), and contraction of the socket (3.0%). No complications were observed after cryotherapy or laser photocoagulation of the tumor.

Conclusions

Ocular complications after treating children with retinoblastoma are common and may seriously affect the quality of life of children surviving the primary malignancy.

Salvage/adjuvant brachytherapy after ophthalmic artery chemosurgery for intraocular retinoblastoma

PURPOSE

To evaluate the efficacy and toxicity of brachytherapy after ophthalmic artery chemosurgery (OAC) for retinoblastoma.

METHODS AND MATERIALS

This was a single-arm, retrospective study of 15 eyes in 15 patients treated with OAC followed by brachytherapy at (blinded institution) between May 1, 2006, and December 31, 2012, with a median 19 months' follow-up from plaque insertion. Outcome measurements included patient and ocular survival, visual function, and retinal toxicity measured by electroretinogram (ERG).

RESULTS

Brachytherapy was used as adjuvant treatment in 2 eyes and as salvage therapy in 13 eyes of which 12 had localized vitreous seeding. No patients developed metastasis or died of retinoblastoma. The Kaplan-Meier estimate of ocular survival was 79.4% (95% confidence interval 48.7%-92.8%) at 18 months. Three eyes were enucleated, and an additional 6 eyes developed out-of-target volume recurrences, which were controlled with additional treatments. Patients with an ocular complication had a mean interval between last OAC and plaque of 2.5 months (SD 2.3 months), which was statistically less (P=.045) than patients without ocular complication who had a mean interval between last OAC and plaque of 6.5 months (SD 4.4 months). ERG responses from pre- versus postplaque were unchanged or improved in more than half the eyes.

CONCLUSIONS

Brachytherapy following OAC is effective, even in the presence of vitreous seeding; the majority of eyes maintained stable or improved retinal function following treatment, as assessed by ERG.

The effect of imatinib mesylate on the proliferation, invasive ability, and radiosensitivity of retinoblastoma cell lines

PURPOSE

Our aim was to evaluate the potential effect of imatinib mesylate (IM), a small molecule that specifically inhibits the tyrosine quinase receptors, on the proliferation and invasive abilities of two human retinoblastoma (Rb) cell lines. Furthermore, the ability of IM to radiosensitize Rb cells was evaluated. The potential targets of IM (C-kit, PDGRF-α and -β, and c-Abl) were also investigated in these cell lines.

METHODS

Two human Rb cell lines (WERI-RB-1 and Y79) were cultured under normal growth conditions. An MTT-based proliferation assay and a Matrigel invasion assay were performed with and without exposure to 10 μM of IM. The cells were also irradiated with graded dosages of 0, 2, 4, 6, 8, and 10 Gy with and without IM and their proliferations rates were analyzed. Western blot and immunocytochemical analysis of cytospins were performed to evaluate the expression of C-kit, PDGRF-α and -β, and c-Abl.

RESULTS

When IM was added to both cell lines a statistically significant (P<0.05) reduction in proliferation and invasive ability were observed. Exposure to IM also significantly increased the radiosensitivity of both Rb cell lines. The c-Abl expression was strongly positive, PDGRF-α and -β expression were also positive but the C-kit expression was negative in both cell lines.

CONCLUSIONS

These results indicate that Gleevec may be useful as an adjuvant treatment in Rb patients, specially those considered for radiation therapy.

Orbital retinoblastoma: Present status and future challenges - A review

Orbital retinoblastoma is a catastrophic event traditionally carrying a dismal prognosis. Although its incidence is less in the developed countries it continues to be one of the major diagnosis at presentation in the developing world. Orbital retinoblastoma encompasses a wide range of distinct clinical entities with varying tumor load. There are no standard treatment protocols as of now but the current preferred management is multimodal with a combination of initial high-dose chemotherapy, surgery, external beam radiotherapy and prolonged chemotherapy for twelve cycles. In spite of progress on all fronts including surgical, medical, diagnostic, genetic and rehabilitative with improving survival rates, however, lack of access to medical facilities, lack of education about the need for early medical attention and cultural resistance to enucleation continue to contribute to an epidemic of extra ocular disease at diagnosis in the developing world. This review introduces the various terminologies used in the spectrum of orbital retinoblastoma, discusses in details the clinical aspects and management protocols, current status and the future directions.

Toxicogenomics of nanoparticulate delivery of etoposide: potential impact on nanotechnology in retinoblastoma therapy

To develop a suitable formulation with high entrapment efficiency, etoposide-loaded poly(lactide-co-glycolide) nanoparticles (NPs) were formulated by single emulsion-solvent evaporation method by changing different formulation parameters such as drug loading, choice of organic solvent and percentage of emulsifier polyvinyl alcohol. The NPs showed higher entrapment efficiency, ~86% (with 15% (w/w) drug loading). The physicochemical parameters revealed smooth topology with size range (240–320 nm), a negative zeta potential (~19 mV) and in vitro sustained-release activity (~60% drug release in 40 days). Greater anti-proliferative activity ~100 times was observed with NPs (IC₅₀ = 0.002 μg/ml) than that of native etoposide (IC₅₀ = 0.2 μg/ml) in retinoblastoma cell line (Y-79). These NPs demonstrated greater (G1/S) blocking and decreased mitochondrial membrane potential as measured by flow cytometry. There was upregulation of apoptotic gene activity in NPs than native etoposide, as revealed through microarray analysis. However, this is the first ever report demonstrating the intricate modulation of genetic network affected by NPs. Collectively, these results suggest that etoposide-loaded NPs could be potentially useful as a novel drug delivery system for retinoblastoma in the future.

Figure

Risk of cataract extraction among adult retinoblastoma survivors

OBJECTIVE

To investigate the risk of cataract extraction among adult retinoblastoma survivors.

DESIGN

A retrospective cohort study was performed on retinoblastoma survivors who received the diagnosis from 1914 to 1984 and were interviewed in 2000. Lens doses were estimated from radiotherapy records. The cumulative time interval to cataract extraction between dose groups was compared using the log-rank test and Cox regression.

RESULTS

Seven hundred fifty-three subjects (828 eyes) were available for analysis for an average of 32 years of follow-up. During this period, 51 cataract extractions were reported. One extraction was reported in an eye with no radiotherapy compared with 36 extractions in 306 eyes with 1 course of radiotherapy and 14 among 38 eyes with 2 or 3 treatments. The average time interval to cataract extraction in irradiated eyes was 51 years (95% confidence interval [CI], 48-54) following 1 treatment and 32 years (95% CI, 27-37) after 2 or 3 treatments. Eyes exposed to a therapeutic radiation dose of 5 Gy or more had a 6-fold increased risk (95% CI, 1.3-27.2) of cataract extraction compared with eyes exposed to 2.5 Gy or less.

CONCLUSIONS

The results emphasize the importance of ophthalmologic examination of retinoblastoma survivors who have undergone radiotherapy. The risk of cataract extraction in untreated eyes with retinoblastoma is comparable with the risk of the general population.

Radiation-induced craniofacial bone growth inhibition: efficacy of cytoprotection following a fractionated dose regimen

BACKGROUND

Severe craniofacial growth disturbances are noted in 66 to 100 percent of children with head and neck cancers who received radiotherapy during their growing years. The authors have previously demonstrated the prevention of radiation-induced craniofacial bone growth inhibition following single-dose orthovoltage radiation to the orbitozygomatic complex in an infant rabbit model through the administration of the cytoprotective agent amifostine (WR-2721) before radiation treatment. The purpose of this study was to investigate the efficacy of cytoprotection using a fractionated dose regimen that better approximates the clinical application of radiation therapy.

METHODS

Thirty 7-week-old male New Zealand rabbits were randomized into three groups (n = 10), each receiving six fractions of orthovoltage radiation to the right orbitozygomatic complex: group C, sham irradiation control; group F35, total dose of 35 Gy; and group F35A, total dose of 35 Gy with administration of amifostine 200 mg/kg intravenously 20 minutes before each fraction. Bone growth was evaluated up to skeletal maturity (age 21 weeks) with serial radiographs and computed tomography scans for cephalometric analysis, bone volume, and bone density measurements.

RESULTS

Fractionated radiation resulted in significant (p < 0.05) bone growth inhibition compared with sham radiation in 16 of 21 cephalometric parameters measured and significantly (p < 0.05) reduced bone volume of the rabbit orbitozygomatic complex. Pretreatment with amifostine before each radiation fraction prevented growth deformities in four cephalometric parameters and significantly (p < 0.05) attenuated these effects in another seven parameters compared with radiated animals. Bone volumes were also significantly (p < 0.05) improved in F35A animals compared with F35 animals.

CONCLUSIONS

This study establishes that fractionation of orthovoltage radiation does not prevent the development of growth disturbances of the rabbit craniofacial skeleton and also demonstrates that preirradiation administration of amifostine is highly effective in the prevention and attenuation of radiation-induced craniofacial bone growth inhibition.

The clinical spectrum and treatment outcome of retinoblastoma in Indian children

PURPOSE

To study the clinical spectrum and treatment outcome of retinoblastoma in Indian children.

PATIENTS AND METHODS

This retrospective study analyzed 488 eyes of 355 retinoblastoma patients treated at a tertiary care ophthalmic hospital in southern India during a 14-year period.

RESULTS

Retinoblastoma involved one eye in 177 (50%) and both eyes in 178 (50%) patients. Mean age at presentation was 23.98 +/- 23.37.

Retinoblastoma: review of 30 years' experience with external beam radiotherapy

A review of the experience at the Peter MacCallum Cancer Centre (Peter Mac), Melbourne, Australia in treating retinoblastoma with external beam radiotherapy was conducted. Outcomes of particular interest were tumour control, vision preservation and treatment late effects. The review was restricted to patients that had intact eyes treated at Peter Mac from 1965 until 1997 with at least 2 years of follow up. Histories were reviewed regarding patient and tumour characteristics and treatment details. Thirty-five patients were identified in whom 47 eyes were treated. Of the tumours, 47% were Reese-Ellsworth stage IV or V and the majority of others were at high risk for vision loss because of tumour location. The radiation treatment technique became increasingly sophisticated during the study period. Radiation dose and fraction size have similarly evolved but most patients received 30-50 Gy. Since 1989, a highly accurate contact lens immobilization technique has been used to deliver 40 Gy in 20 fractions. Thirteen eyes required additional local therapy. Of the treated eyes, 34 (72%) remain intact and 74% of these have useful vision. One patient died from retinoblastoma and three from second malignant neoplasms. With modern radiotherapy, late toxicities other than growth arrest and non-progressive cataract did not occur during the study period. Tumour control was high and a very acceptable rate of organ and vision preservation was achieved in a relatively high-risk population. Modern radiotherapy continues to develop in an attempt to improve treatment accuracy and minimize late radiation toxicity.

Efficacy of radioprotection in the prevention of radiation-induced craniofacial bone growth inhibition

It has been reported that radiotherapy-induced craniofacial deformities can occur in 66 to 100 percent of survivors of childhood head and neck cancers. Recent interest in the effectiveness of radioprotectors in the protection of normal tissue against radiation injury led us to investigate a possible role of radioprotection in the prevention of radiation-induced craniofacial bone growth inhibition. Therefore, the objective of this study was to use the radioprotective agent amifostine (Ethyol, WR-2721) as a probe to determine the effectiveness of radioprotection in the prevention of radiation-induced craniofacial bone growth inhibition after single-dose orthovoltage radiation to the infant rabbit orbital-zygomatic complex. Seven-week-old male New Zealand white rabbits were randomized into three groups (n = 10 each): group 1, 0 Gy (sham radiation); group 2, 35-Gy single-dose orthovoltage radiation; and group 3, 35-Gy single-dose orthovoltage radiation and amifostine (300 mg/kg intravenously, given 20 minutes before radiation). Serial radiographs and computed tomographic scans were obtained for cephalometric analysis, bone volume, and bone density measurements until skeletal maturity at 21 weeks. Significant (p < 0.05) reductions in orbital-zygomatic complex linear bone growth, bone volume, and bone density were observed after 35-Gy radiation compared with nonirradiated controls. No significant differences were noted between groups in cephalometric analysis of the nontreated (nonirradiated) left orbital-zygomatic complex, indicating no crossover effect from the radiation beam. However, pretreatment with amifostine, 20 minutes before 35-Gy radiation, resulted in significant (p < 0.05) preservation of linear bone growth, bone volume, and bone mineral density in the rabbit orbital-zygomatic complex compared with controls. This study demonstrated for the first time the effectiveness of a radioprotector in the prevention of radiation-induced craniofacial bone growth inhibition, and it paves the way for investigation into the pathogenic mechanism and prevention of radiotherapy-induced craniofacial deformities.

Radiation-induced craniofacial bone growth inhibition: development of an animal model

Craniofacial deformities caused by therapeutic radiation-induced bone growth inhibition can occur in up to 100% of survivors of childhood head and neck cancers. The mechanism of radiation-induced craniofacial bone growth inhibition is poorly understood. The objective of this study is to establish a model of radiation-induced craniofacial bone growth inhibition to study the pathophysiology of radiation on growing membranous bone. Seven-week-old male New Zealand white rabbits were randomized into 4 groups (n = 10/group) and received a single dose of orthovoltage radiation (0, 15, 25, or 35 Gy) to the right orbital-zygomatic complex. Serial radiographs and computed tomography scans were performed for cephalometric analysis, bone volume, and bone density measurements until skeletal maturity at 21 weeks. Statistically significant ( P < 0.05) reductions in orbital-zygomatic complex linear bone growth, bone volume, and bone density were found after radiation with 25 or 35 Gy compared with nonirradiated control animals. A significant ( P < 0.05) decrease in orbital-zygomatic complex volume was noted after 15-Gy radiation but there were no significant effects on linear bone growth as assessed by cephalometric analysis at this dose. This study establishes the rabbit orbital-zygomatic complex as a suitable model for the study of radiation-induced craniofacial bone growth inhibition and will permit investigation into the underlying cellular and molecular basis of this injury.

Chemotherapy for eye cancer

Chemotherapy has been used to treat a multitude of eye cancers. We attempted to review the role of chemotherapy in the treatment of ocular, adnexal, and orbital malignancies by conducting an extensive search of the medical literature. Unfortunately, the published reports typically contain few patients with limited follow-up, precluding definitive recommendations. For most eye cancers, multicenter trials will offer the potential to gather the numbers of patients required to determine the clinical utility of chemotherapy.

Brachytherapy in primary ocular tumors

Patients with primary ocular tumors are seen infrequently in the medical profession, and most of these patients are referred to specialty centers which has resulted in a good study population. In the past, ocular tumors were treated with enucleation, but the current emphasis is now on organ preservation with sparing of all or partial visual acuity. In the management of these tumors, plaque brachytherapy and particle beam therapy have been used more frequently as an alternative to enucleation. A multi-institutional study, the Collaborative Ocular Melanoma Study (COMS), is currently underway, organized by the National Eye Institute. The COMS isotope of choice is Iodine-125 (I-125). Recurrence after plaque therapy is approximately 15%, although it may be as high as 37% at 15 years for metastatic disease. In one study, nondiffuse iris melanoma has been controlled in 93% of patients by custom plaques utilizing I-125. Plaque brachytherapy also utilizes I-125 for the treatment of retinoblastoma tumors either as primary therapy or following external beam radiation. Currently, through the utilization of plaque radiation therapy, enucleation may be avoided in the majority of patients, and many patients may retrieve some visual acuity. We will review plaque brachytherapy techniques, diagnosis, staging, and some of the pertinent literature of the two most frequently encountered primary ocular tumors: choroidal melanoma, sometimes referred to as uveal melanoma, with an incidence of approximately 1,500 new cases per year in the adult population; and retinoblastoma, the most common intraocular primary malignancy found in childhood, with a frequency of approximately 250 [corrected] new cases per year.

External beam radiation therapy and retinoblastoma: long-term results in the comparison of two techniques

PURPOSE

This study compares the long-term actuarial local control, eye conservation rate, survival, and ocular complications in children with retinoblastoma treated with two different external beam treatment techniques.

METHODS AND MATERIALS

From 1979-1991, 182 eyes in 123 children (104 bilateral) received primary external beam radiation therapy. An anterior lens-sparing electron beam technique delivering 38 to 50 Gy in 2.5 Gy fractions was used in 67 eyes from 1979-1984 and a modified lateral beam technique, delivering 42 to 46 Gy in 2 Gy fractions, was used in 113 eyes from 1984-1991. These groups were balanced with respect to known prognostic variables.

RESULTS

For Group I-III eyes, the 5- and 8-year local control was significantly improved using the modified lateral beam technique (84%) compared to (38%) using the anterior lens sparing technique (p < or = 0.0001). For Group IV-V eyes, the 5- and 8-year local control rates were not statistically different, despite a trend favoring the modified lateral beam technique. Survival endpoints including eye survival (no enucleation), cause-specific survival, and overall survival comparing the two treatment techniques were not significantly different. Overall, 22% of eyes developed cataracts. There was no difference between the two treatment groups in terms of cataract development. No eyes required enucleation for ocular complications.

CONCLUSION

There is a significant improvement in local control using the modified lateral beam technique compared to an anterior lens-sparing approach for Group I-III eyes. However, there was no difference in survival end points between the two treatment techniques. The incidence of ocular complications using these two external beam techniques is acceptable.

Late effects of radiation on the eye and ocular adnexa

A clinically useful classification system is suggested that can be used in prospective trials to evaluate the effects of radiation on the visual system. We review radiation-induced pathophysiological and clinical changes of the various ocular structures as well as dose-response data and management of ocular complications. The rationale for the classification scheme chosen is also discussed.

Visual outcomes of macular retinoblastoma after external beam radiation therapy

PURPOSE

To determine the risk factors that influence the visual outcomes of patients with macular retinoblastoma who are treated with radiation therapy.

METHODS

The medical records of all patients with macular retinoblastoma treated with radiation therapy between 1980 and 1990 were reviewed. Ten patients were entered into the study. Features analyzed included patient age, laterality of eye involvement, location and size of macular tumor(s) at the time of diagnosis, treatment course, and most recent visual acuity.

FINDINGS

Ten of 11 eyes (10 patients) were successfully treated with external beam radiation. Eight patients obtained visual acuities ranging from 20/25 to 20/100; two patients had visual acuities of 20/200 or less. The best visual acuities were noted in patients whose tumor(s) did not involve the fovea and were relatively small. The worse visual acuities were noted in patients with binocular vision whose tumors invaded the fovea and were larger in size. In two of three patients in whom both eyes were retained, superimposed amblyopia developed in the eye with macular retinoblastoma.

CONCLUSION

The authors' findings indicate that most patients with macular retinoblastoma who are treated with external beam radiation have favorable visual outcomes, but final visual acuity depends on the size of the tumor and involvement of the fovea. Patients in whom both eyes are retained are predisposed to further visual loss from amblyopia.

Hypofractionation in retinoblastoma: an increased risk of retinopathy

Forty-four eyes in 38 children were treated between 1963 and 1991 by external radiotherapy for retinoblastoma. Treatment modalities varied widely during this period; in addition to radiotherapy there was chemotherapy (16/44), photocoagulation (14/44), and laser therapy or cryotherapy (14/44). Treatment technique and dose fractionation also varied widely; lateral beam technique (39/44) versus anterior or anterior/lateral beam; doses per fraction ranged from 1 to 4.5 Gy, total doses from 30 to 61.5 Gy, and overall times from 22 to 49 days. Patients were followed at 3-month intervals, and actuarial survival at 10 years was 88%, with 62% local control. Ten eyes showed clinical evidence of retinopathy. A multivariate analysis of factors associated with increased risk of retinopathy was carried out using the Cox proportional hazards model and the mixture model of Farewell. The estimated latent time was 17 months (95% confidence interval, 14-20 months). The only factors found to be significantly associated with retinopathy were total dose multiplied by dose per fraction, or total dose normalized to the equivalent total dose in 2-Gy fractions as estimated from the LQ model, and these gave equivalent descriptions. There were trends (not significant) for increased risk of retinopathy when treatments included chemotherapy or photocoagulation, and for decreased risk (also not significant) when cryotherapy was used in conjunction with radiotherapy. No significance could be attached to any of the following: number of sites per eye, Reese-Ellsworth stage, and family history. We conclude that hypofractionation carries a significant risk for retinopathy in the treatment of retinoblastoma.

Malignant fibrous histiocytoma in childhood

BACKGROUND

Malignant fibrous histiocytoma (MFH) is a neoplasm of late adult life and often is reported in the pediatric population. It is thought to behave more benignly in children than in adults.

METHOD

Clinical and pathologic features, treatment, and outcome of nine pediatric patients seen at British Columbia's Children's Hospital between 1983 and 1990 were examined. The literature regarding pediatric malignant fibrous histiocytoma was reviewed.

RESULTS

The tumors included one primary renal tumor and two occurring in the orbit after radiation therapy for retinoblastoma during the neonatal period. Histologic examination showed that six tumors had a storiform-pleomorphic pattern, one was myxoid, and two were angiomatoid in type. Six children are alive with a disease-free survival of 20 months to 8 years after surgical resection. Two of these received adjuvant chemotherapy, none had radiation therapy. Three patients have died of disease, two with pulmonary metastases that developed despite multiagent chemotherapy and radiation therapy. Poor outcome was associated with large tumors, deep and proximal location, and the storiform-pleomorphic histologic type with atypical mitoses.

CONCLUSION

Malignant fibrous histiocytoma is similar in children and adults. Surgery is the mainstay of therapy, but the risk of local recurrence and pulmonary metastases indicates the need for adjuvant therapy in selected patients.

Retinoblastoma: a review

Retinoblastoma is the most common primary ocular malignancy in childhood, usually occurring below the age of five. Recent advances in molecular biology have enabled understanding of retinoblastoma tumorigenesis as well as detecting carriers of the mutant retinoblastoma allele. It is possible now to predict prenatally whether a child carries the retinoblastoma genome. This has enabled early detection of retinoblastoma and improved outcome. Also these children are at risk for mesenchymal tumors in early adult life necessitating life long vigilance. Great strides have been made in the management of retinoblastoma. Introduction of a new pathological staging system and addition of combination chemotherapy for extraocular disease has led to more than 80% long term disease free survivors in this group of patients, who earlier had a very poor outcome. For localized intraocular disease, local treatment seems to be all that is necessary. Newer radiation techniques have helped preserve useful vision and reduced radiation related side effects.

Choroidoretinal neovascularisation following radon seed treatment of retinoblastoma in two patients

Two patients who developed localised radiation retinopathy many years after brachytherapy for retinoblastoma are described. In both patients extracapsular cataract extraction and YAG laser capsulotomy were followed by preretinal and vitreous haemorrhage and in one patient there was deterioration of existing radiation retinopathy with macular oedema. Premacular and vitreous haemorrhage occurred from focal, preretinal neovascular membranes which appeared to originate from residual choroidal vascular radicals. Laser photocoagulation was successful in ablating preretinal neovascular membranes and limiting the extent of macular oedema from incompetent retinal capillaries adjacent to the atrophic macular scars.

Plaque radiotherapy in the management of retinoblastoma. Use as a primary and secondary treatment

BACKGROUND

Radioactive episcleral plaque brachytherapy is a treatment method for selected retinoblastomas. The authors have used this technique since 1976 as both a primary and a secondary treatment method after other methods failed to achieve tumor control.

METHODS

A review of the records of 400 consecutive children with retinoblastoma showed that solitary plaque radiotherapy was used as a method of management in 103 cases. The authors' overall experience was evaluated, and the results between primary and secondary plaque therapies were compared in these 103 cases.

RESULTS

Of the 103 tumors, the mean basal diameter was 7 mm, and the mean thickness was 4 mm. Overlying vitreous seeds were clinically apparent in 50 cases (48%). The mean proximity of the tumor margin to the optic disc margin was 6 mm and to the foveola was 6 mm. The mean follow-up period was 40 months. In 89 cases (86%), the tumor was controlled by one plaque application, whereas in 13 cases (13%), tumor recurrence after initial tumor shrinkage necessitated subsequent treatment. Final visual outcome was good in 63 cases (62%), poor in 30 (29%), enucleation in 9 (9%), and unknown in 1 case. The poor vision was due to foveal retinoblastoma (with or without amblyopia) in 25 cases (83%). Eight of the nine enucleated eyes were treated initially with external beam radiotherapy then later with plaque radiotherapy. In 31 cases (30%), plaque radiotherapy was used as a primary treatment to the tumor, while in 72 cases (70%), it was a secondary form of management after failure of other methods to control the tumor. Statistical analysis showed that tumors treated with plaque radiotherapy as a primary measure were more likely to be larger in in base (P = 0.01) and thickness (P = 0.01) than secondary treated tumors. The secondary treated retinoblastomas were more likely to have vitreous seeds (P = 0.02) than the primary treated tumors. The rate of tumor control and patient survival was similar between the two groups.

CONCLUSION

Plaque radiotherapy is very effective in treating selected retinoblastomas with a high rate of tumor control and patient survival. It can be used successfully as a primary or a secondary treatment for tumors that have not been adequately controlled by other therapeutic methods.

Sinonasal small cell neoplasm developing after radiation therapy for retinoblastoma: an immunohistologic, ultrastructural, and cytogenetic study

Patients with retinoblastoma have an increased risk of developing second primary tumors. Only a few examples of sinonasal small cell neoplasms developing after radiation therapy for retinoblastoma have been reported. We report one such case that developed 18 years after treatment for retinoblastoma. Histologic examination revealed a small, blue, round cell tumor without rosettes or cytoplasmic glycogen. Immunohistochemically, the tumor cells were positive for neuron-specific enolase, synaptophysin, and S-100 protein, but negative for epithelial and mesenchymal markers, suggesting that this was a primitive neuroectodermal tumor. Cytogenetic studies of this tumor failed to reveal the chromosome 13 abnormality typical of retinoblastoma and the t(11:22) translocation typical of the group of peripheral neuroepitheliomas.

A unique case of retinoblastoma masked by retinal detachment diagnosis and management

A 4-year-old Latin American boy presented with a history of loss of vision of his left eye for 7 months. He was followed by different ophthalmologists and diagnosed with a retinal detachment. Computerized tomograms and magnetic resonance imaging demonstrated a large calcified left eye and markedly enlarged optic nerve. Based on these radiologic findings diagnosis of retinoblastoma was strongly suspected. Initially enucleation was not done because it was thought that cutting through the involved optic nerve would cause dissemination. The patient was treated with chemotherapy which resulted in marked response. Following normalization of optic nerve and after irradiation the eye was enucleated. The diagnosis of retinoblastoma was confirmed. No tumor was found in the optic nerve. The importance of imaging studies in diagnosis of retinoblastoma and the role of chemotherapy in the treatment of primary retinoblastoma are emphasized.