Incidence of anterior pituitary deficiency after radiotherapy at an early age: study in retinoblastoma

Growth Hormone Deficiency and Treatment in Childhood Cancer Survivors

Growth hormone (GH) deficiency is a common pituitary hormone deficiency in childhood cancer survivors (CCS). The identification, diagnosis, and treatment of those individuals at risk are important in order to minimize associated morbidities that can be ameliorated by treatment with recombinant human GH therapy. However, GH and insulin-like growth factor-I have been implicated in tumorigenesis, so there has been concern over the use of GH therapy in patients with a history of malignancy. Reassuringly, GH therapy has not been shown to increase risk of tumor recurrence. These patients have an increased risk for development of meningiomas, but this may be related to their history of cranial irradiation rather than to GH therapy. In this review, we detail the CCS who are at risk for GHD and the existing evidence on the safety profile of GH therapy in this patient population.

DIAGNOSIS OF ENDOCRINE DISEASE: Endocrine late-effects of childhood cancer and its treatments

Endocrine complications are frequently observed in childhood cancer survivors (CCS). One of two CCS will experience at least one endocrine complication during the course of his/her lifespan, most commonly as a late-effect of cancer treatments, especially radiotherapy and alkylating agent chemotherapy. Endocrine late-effects include impairments of the hypothalamus/pituitary, thyroid and gonads, as well as decreased bone mineral density and metabolic derangements leading to obesity and/or diabetes mellitus. A systematic approach where CCS are screened for endocrine late-effects based on their cancer history and treatment exposures may improve health outcomes by allowing the early diagnosis and treatment of these complications.

Analysis of patient outcomes following proton radiation therapy for retinoblastoma

PURPOSE

Proton radiotherapy (PRT) is used in the treatment of retinoblastoma (RB) and has the potential to minimize exposure of normal tissue to radiation and thus decrease risk of toxicity and second malignancies. However, comprehensive analyses of long-term patient outcomes are not available.

METHODS

RB patients treated with PRT at our institution between 1986 and 2012 were invited to return for participation in a study designed to assess long-term outcomes. Enrolled patients underwent comprehensive analysis including oncologic, ophthalmic, endocrine, cephalometric, and quality of life (QOL) assessments.

RESULTS

A total of 12 patients were enrolled in this study, and the average length of follow-up among enrolled patients was 12.9 years (range 4.8-22.2 years). All enrolled patients had bilateral disease, and the disease and visual outcomes for enrolled patients were similar to outcomes for all RB patients treated with PRT over the same time period at our institution. Endocrine evaluation revealed no growth abnormalities or hormonal deficiencies across the cohort. Based on MRI and external cephalometry, PRT was associated with less facial hypoplasia than enucleation. Patient and parent-proxy QOL assessments revealed that RB treatment did not appear to severely impact long-term QOL.

CONCLUSIONS

In addition to providing an opportunity for long-term disease control and functional eye preservation, PRT does not appear to be associated with unexpected late visual, endocrine, or QOL effects in this cohort.

Prevalence and risk factors of radiation-induced growth hormone deficiency in childhood cancer survivors: a systematic review

BACKGROUND

Growth hormone deficiency (GHD) is usually the first and most frequent endocrine problem occurring after cranial radiotherapy (CRT). The aim of this systematic review was to evaluate the existing evidence of the prevalence and risk factors of radiation-induced GHD in childhood cancer survivors.

METHODS

MEDLINE, EMBASE and CENTRAL were searched for studies reporting on radiation-induced GHD in childhood cancer survivors. Information about study characteristics, prevalence and risk factors was abstracted and the quality of each study was assessed. A meta-regression analysis was performed.

RESULTS

The prevalence of radiation-induced GHD was estimated in 33 studies. Most studies had methodological limitations. The prevalence varied considerably between 0% and 90.9%. Selecting only the studies with adequate peak GH cut-off limits (<5 microg/L) resulted in 3 studies. In these studies the prevalence ranged from 29.0% to 39.1%, with a pooled prevalence of 35.6%. Higher CRT dose and longer follow-up time have been suggested to be the main risk factors of GHD by studies included in this review. The meta-regression analysis showed that the wide variation in the prevalence of GHD could be explained by differences in maximal CRT dose.

CONCLUSIONS

GHD is a frequent consequence after CRT in childhood cancer survivors. The prevalence of radiation-induced GHD ranged from 29.0% to 39.1% when selecting only studies with adequate peak GH cut-off limits. Higher CRT dose and longer follow-up time are the main risk factors. More well-designed studies are needed to accurately estimate the prevalence of GHD and to define the exact CRT threshold dose.

Postenucleation orbits in retinoblastoma: treatment with 125I brachytherapy

PURPOSE

Children with retinoblastoma that extends into or through the choroid, sclera, or optic nerve are at risk of developing orbital disease, as well as metastases. Previously, these enucleated orbits were treated with external beam radiotherapy in addition to chemotherapy. 125I brachytherapy for tumors in and around the eye was pioneered by Sealy in Cape Town, South Africa, in 1974. In 1983, he developed a technique to irradiate the contents of the orbit while limiting the dose to the bony orbit and eyelids.

METHODS AND MATERIALS

Six nylon tubes containing 125I seeds were implanted through the eyelids around the periphery of the orbit. Each contained a metal gutter that screens the outer part of the seeds from the bony orbit. A seventh unscreened tube was placed in the center, and a metal disc with 125I seeds on its posterior surface was secured beneath the eyelids. Between 1983 and 2000, 57 orbits were treated in 56 children with retinoblastoma. Thirty-six were treated prophylactically and 21, with tumor at the resection line of the nerve, extrascleral tumor, or metastases, were treated therapeutically. They received a median dose of 34 Gy in 70 h; 30 also received chemotherapy. Children with tumor at the resection line of the nerve also received treatment to the craniospinal axis.

RESULTS

The median follow-up of the 35 patients treated prophylactically was 35 months (range 0-187). Seven patients died, 6 of metastases, at a median of 10 months (range 4-29) after the implant. Eight of the 13 patients with microscopic extraocular tumor survived a median of 29 months (range 5-156). None of the 8 patients presenting with orbital tumor or metastases survived. No orbital recurrences developed in any of the patients. Cosmesis was considerably improved compared with previous forms of irradiation.

CONCLUSION

Orbital brachytherapy is an effective method of irradiating the orbit to prevent recurrent tumor, the treatment time is short, and the cosmesis is much more acceptable than with other forms of irradiation. No facial atrophy or second nonocular tumors have occurred.

Endocrine complications of pediatric brain tumors: case series and literature review

The survival rate for childhood cancer, including brain tumors, is increasing. As a result, long-term sequelae of chemotherapy and radiotherapy are also increasing. The purpose of this study was to determine the frequency of endocrine complications of therapy for brain tumors in pediatric patients. Endocrinopathy was observed in 19 of 20 (95%) of patients with supratentorial midline tumors. Fifty-seven patients with nonmidline tumors (22 supratentorial, 35 posterior fossa) were followed for a mean of 4.6 +/- 2.4 years. Twenty-two endocrinopathies occurred in 16 patients treated as follows: one of 23 patients (0.4%) had surgery alone, zero of four (0%) had chemotherapy alone, eight of 18 (44%) had radiotherapy alone, and seven of 12 (58%) had both radiotherapy and chemotherapy. Endocrine disturbance was particularly common after craniospinal radiation (10 of 18 [55%]). Growth failure occurred in none of 23 patients who had surgery alone, in one of four patients who had chemotherapy (25%), in 11 of 18 patients who had radiotherapy (61%), in seven of 12 patients who received both radiotherapy and chemotherapy (58%), and in 12 of 18 patients who had craniospinal radiation (67%). In conclusion, endocrine and growth disturbances are uncommon with surgery alone, although they occurred in 53 and 60%, respectively, of patients treated with cranial irradiation for a brain tumor. This finding underscores the importance of routine endocrinology follow-up for all brain tumor patients receiving cranial irradiation. Literature review and endocrine surveillance recommendations are included.

Chemothermotherapy in the management of retinoblastoma

OBJECTIVE

To evaluate the results of chemothermotherapy for the treatment of retinoblastoma.

DESIGN

Non-comparative interventional case series.

PATIENTS

Fifty-one children (65 eyes and 103 tumors) were treated with chemothermotherapy in a single institution from January 1995 to May 1998.

METHODS

Chemothermotherapy consists of a combination of transpupillary thermotherapy delivered shortly after intravenous (IV) injection of carboplatin (560 mg/m(2)). Each tumor is treated separately with a diode laser using a microscope. Laser intensity, spot size, and duration are adapted to the size of each tumor and to the clinical response. After 8 days, thermotherapy alone is repeated. This cycle is performed from one to six times, every 28 days. The treatment data and outcome are analyzed separately.

MAIN OUTCOME MEASURES

Assessment of local tumor control.

RESULTS

One hundred three tumors were treated in 65 eyes of 51 children. Age at diagnosis was 0 to 60 months (median, 7 months). Median tumor diameter at the time of treatment was 3.5 mm (range, 1.5-12 mm). Laser modalities were as follows: median intensity, 450 mW (range, 150-1000 mW); median spot size, 1.2 mm (range, 0.3-2.0 mm); and median number of cycles required to obtain tumor control, three. Tumor regression was obtained for 99 tumors (96.1%) after a median follow-up of 30 months (17-61 months). Seven tumors relapsed after initial control (6.8%). Salvage treatment (external beam radiation, iodine plaques, or enucleation) was necessary for a total of 11 tumors (10.7%). The only risk factor for relapse was the initial diameter of the lesion greater than 3.5 mm, whereas the other tumor characteristics or treatment variables were not significantly correlated with relapse. Ninety-seven percent of treated eyes were able to be preserved, and 92% of cases were treated without external beam radiation.

CONCLUSIONS

Chemothermotherapy is an effective technique to treat small- to medium-sized retinoblastomas in children, avoiding external beam irradiation.

Role of chemotherapy alone or in combination with hyperthermia in the primary treatment of intraocular retinoblastoma: preliminary results

BACKGROUND

The efficacy of the etoposide-carboplatin combination in extraocular retinoblastoma is well known. This drug combination is therefore used in intraocular retinoblastoma, as primary reduction chemotherapy, before local treatment. The use of carboplatin in combination with diode laser hyperthermia as local treatment (thermochemotherapy) has been recently described as a conservative approach avoiding external beam radiotherapy in posterior pole tumours.

METHODS

All patients were reviewed, who were treated for retinoblastoma at the Institut Curie between June 1994 and October 1995, in whom treatment included either reduction chemotherapy or thermochemotherapy or both modalities successively. 23 patients presenting with unilateral (three) or bilateral (20) intraocular retinoblastoma received neoadjuvant chemotherapy consisting of two courses of etoposide 150 mg/m2/day and carboplatin 200 mg/m2/day for 3 days. 15 patients (17 eyes), eight of whom had already received neoadjuvant chemotherapy, were treated by thermochemotherapy.

RESULTS

Neoadjuvant chemotherapy: overall, seven eyes in seven patients could be treated conservatively, avoiding external beam irradiation, with a median follow up of 14 months. Thermochemotherapy: external beam irradiation was avoided for 14 of the 17 eyes treated.

CONCLUSION

Integration of neoadjuvant chemotherapy and combined treatment with carboplatin and diode laser, into the therapeutic armamentarium for retinoblastoma allows use of more aggressive treatments such as enucleation and external beam radiation.

Dose dependency of time of onset of radiation-induced growth hormone deficiency

Growth hormone (GH) secretion during insulin-induced hypoglycemia was assessed on 133 occasions in 82 survivors of childhood malignant disease. All had received cranial irradiation with a dose range to the hypothalamic-pituitary axis of 27 to 47.5 Gy (estimated by a schedule of 16 fractions over 3 weeks) and had been tested on one or more occasions between 0.2 and 18.9 years after treatment. Results of one third of the GH tests were defined as normal (GH peak response, greater than 15 mU/L) within the first 5 years, in comparison with 16% after 5 years. Stepwise multiple linear regression analysis showed that dose (p = 0.007) and time from irradiation (p = 0.03), but not age at therapy, had a significant influence on peak GH responses. The late incidence of GH deficiency was similar over the whole dose range (4 of 26 GH test results normal for less than 30 Gy and 4 of 25 normal for greater than or equal to 30 Gy after 5 years), but the speed of onset over the first years was dependent on dose. We conclude that the requirement for GH replacement therapy and the timing of its introduction will be influenced by the dose of irradiation received by the hypothalamic-pituitary axis.

Irradiation-induced growth failure

Short stature may complicate the treatment during childhood of brain tumours and, to a lesser extent, ALL. A number of factors may be responsible, including spinal irradiation, malnutrition, recurrent tumour, chemotherapy, precocious puberty and radiation-induced GH deficiency. GH is always the first pituitary hormone to be affected by radiation damage to the hypothalamic-pituitary axis but larger radiation doses may result in panhypopituitarism. Some children retain normal GH responses to certain provocative stimuli, although physiological GH secretion is reduced. Nonetheless, in children suspected of radiation-induced GH deficiency, pharmacological tests of GH secretion remain useful, the ITT being the test of choice because of the marked radiation sensitivity of the GH response to hypoglycaemia. The hypothalamus is more radiosensitive than the pituitary. In many patients with radiation-induced GH deficiency, the damage appears to be at the hypothalamic level resulting in a deficiency of endogenous GRF. Treatment with synthetic GRF may provide an alternative to GH therapy in such children. Finally, there is no evidence to suggest that GH therapy given to a child with radiation-induced GH deficiency might induce a brain tumour recurrence or a relapse of ALL.