Response to growth hormone treatment and final height after cranial or craniospinal irradiation

Risks of Spinal Abnormalities and Growth Impairment After Radiation to the Spine in Childhood Cancer Survivors: A PENTEC Comprehensive Review

PURPOSE

A PENTEC (Pediatric Normal Tissue Effects in the Clinic) review was performed to estimate the dose-volume effects of radiation therapy on spine deformities and growth impairment for patients who underwent radiation therapy as children.

METHODS AND MATERIALS

A systematic literature search was performed to identify published data for spine deformities and growth stunting. Data were extracted from 12 reports of children irradiated to the spine (N = 603 patients). The extracted data were analyzed to find associations between complication risks and the radiation dose (conventional fractionation throughout) as impacted by exposed volumes and age using the mixed-effects logistic regression model. When appropriate, corrections were made for radiation modality, namely orthovoltage beams.

RESULTS

In the regression analysis, the association between vertebral dose and scoliosis rate was highly significant (P < .001). Additionally, young age at time of radiation was highly predictive of adverse outcomes. Clinically significant scoliosis can occur with doses ≥15 Gy to vertebrae during infancy (<2 years of age). For children irradiated at 2 to 6 years of age, overall scoliosis rates of any grade were >30% with doses >20 Gy; grade 2 or higher scoliosis was correlated with doses ≥30 Gy. Children >6 years of age remain at risk for scoliosis with doses >30 Gy; however, most cases will be mild. There are limited data regarding the effect of dose gradients across the spine on degree of scoliosis. The risk of clinically meaningful height loss was minimal when irradiating small volumes of the spine up to 20 Gy (eg, flank irradiation), except in infants who are more vulnerable to lower doses. Growth stunting was more frequent when larger segments of the spine (eg, the entire spine or craniospinal irradiation) were irradiated before puberty to doses >20 Gy. The effect was modest when patients were irradiated after puberty to doses >20 Gy.

CONCLUSIONS

To reduce the risk of kyphoscoliosis and growth impairment, the dose to the spine should be kept to <20 Gy for children <6 years of age and to <10 to 15 Gy in infants. The number of vertebral bodies irradiated and dose gradients across the spine should also be limited when possible.

Response to GH Treatment After Radiation Therapy Depends on Location of Irradiation

OBJECTIVES

Cancer survivors with GH deficiency (GHD) receive GH therapy (GHT) after 1+ year observation to ensure stable tumor status/resolution.

HYPOTHESIS

Radiation therapy (RT) to brain, spine, or extremities alters growth response to GHT.

AIM

Identify differences in growth response to GHT according to type/location of RT.

METHODS

The Pfizer International Growth Database was searched for cancer survivors on GHT for ≥5 years. Patient data, grouped by tumor type, were analyzed for therapy (surgery, chemotherapy, RT of the focal central nervous system, cranial, craniospinal, or total body irradiation [TBI] as part of bone marrow transplantation), sex, peak stimulated GH, age at GHT start, and duration from RT to GHT start. Kruskal-Wallis test and quantile regression modeling were performed.

RESULTS

Of 1149 GHD survivors on GHT for ≥5 years (male 733; median age 8.4 years; GH peak 2.8 ng/mL), 431 had craniopharyngioma (251, cranial RT), 224 medulloblastoma (craniospinal RT), 134 leukemia (72 TBI), and 360 other tumors. Median age differed by tumor group (P < 0.001). Five-year delta height SD score (SDS) (5-year ∆HtSDS; median [10th-90th percentile]) was greatest for craniopharyngioma, 1.6 (0.3-3.0); for medulloblastoma, 5-year ∆HtSDS 0.9 (0.0-1.9); for leukemia 5-year ∆HtSDS, after TBI (0.3, 0-0.7) versus without RT (0.5, 0-0.9), direct comparison P < 0.001. Adverse events included 40 treatment-related, but none unexpected.

CONCLUSIONS

TBI for leukemia had significant impact on growth response to GHT. Medulloblastoma survivors had intermediate GHT response, whereas craniopharyngioma cranial RT did not alter GHT response. Both craniospinal and epiphyseal irradiation negatively affect growth response to GH therapy compared with only cranial RT or no RT.

Final height in growth hormone-deficient childhood cancer survivors after growth hormone therapy

PURPOSE

Growth hormone deficiency (GHD) is the most prevalent hypothalamic-pituitary (HP) disorder found in childhood cancer survivors (CCS). The published studies assessing GHD in CCS concluded that recombinant human GH (rhGH) does not restore final height (FH) to that predicted from mid-parental height (MPH). Thus, wider analyses on final height outcomes after rhGH in CCS are needed.

METHODS

Retrospective study on final height (FH) in 87 CCS treated with rhGH. Patients were divided into: Group A (n =48) who underwent cranial radiotherapy or had non-irradiated tumours of HP area, and B (n =39) who were treated with craniospinal or total body irradiation (TBI). 19/87 patients with central precocious/early puberty also received GnRH analogues.

RESULTS

Height (HT) gain after 1 and 2 years of rhGH was 0.38 ± 0.35 SDS and 0.18 ± 0.30 SDS, respectively (P < 0.0001); mean FH was in the normal range (- 0.85 ± 1.34 SDS), though not significantly different from HT SDS at baseline. 67% overall failed to reach MPH especially in Group B (P < 0.0001). However, height loss (HT SDS-MPH SDS) at FH improved or remained stable compared to baseline in 26/45 patients (58%). On stepwise regression analysis, major determinants of FH were HT at baseline (P < 0.0001) and delay before start of rhGH (P = 0.012). There was no significant difference in FH when GnRHa was added to rhGH.

CONCLUSION

rhGH and GnRH analogues therapy, when indicated, though failing to induce catch-up growth, prevented further height loss leading to a FH within the normal range but still below MPH, this latter being statistically significant in children who received craniospinal and TBI.

Growth Disturbances in Childhood Cancer Survivors

Survival from childhood cancer has improved dramatically over the last few decades, resulting in an increased need to address the long-term follow-up and care of childhood cancer survivors. Appropriate linear growth is an important measure of health, with alterations of growth in children and short adult height in those who have completed growth serving as potential indicators of the sequelae of the underlying diagnosis or the cancer treatments. It is therefore critical that clinicians, particularly endocrinologists, be familiar with the patterns of altered growth which may be seen following diagnosis and treatment for childhood cancer. In this article, we will review the growth alterations seen in childhood cancer survivors, focusing on risk factors and considerations in evaluation and care.

Hypothalamic-Pituitary and Growth Disorders in Survivors of Childhood Cancer: An Endocrine Society Clinical Practice Guideline

OBJECTIVE

To formulate clinical practice guidelines for the endocrine treatment of hypothalamic-pituitary and growth disorders in survivors of childhood cancer.

PARTICIPANTS

An Endocrine Society-appointed guideline writing committee of six medical experts and a methodologist.

CONCLUSIONS

Due to remarkable improvements in childhood cancer treatment and supportive care during the past several decades, 5-year survival rates for childhood cancer currently are >80%. However, by virtue of their disease and its treatments, childhood cancer survivors are at increased risk for a wide range of serious health conditions, including disorders of the endocrine system. Recent data indicate that 40% to 50% of survivors will develop an endocrine disorder during their lifetime. Risk factors for endocrine complications include both host (e.g., age, sex) and treatment factors (e.g., radiation). Radiation exposure to key endocrine organs (e.g., hypothalamus, pituitary, thyroid, and gonads) places cancer survivors at the highest risk of developing an endocrine abnormality over time; these endocrinopathies can develop decades following cancer treatment, underscoring the importance of lifelong surveillance. The following guideline addresses the diagnosis and treatment of hypothalamic-pituitary and growth disorders commonly encountered in childhood cancer survivors.

Decreased Pituitary Height and Stunted Linear Growth After Radiotherapy in Survivors of Childhood Nasopharyngeal Carcinoma Cases

To examine the morphological changes of the pituitary glands and linear growth of childhood nasopharyngeal carcinoma (NPC) cases who accepted radiotherapy. A total of 90 children (i.e., age less than 18 years) who were diagnosed as NPC at Sun Yat-sen University Cancer Center from January 2009 to January 2016 were identified by reviewing medical records. Two radiologists reviewed and measured the pre-radiation, post-radiation, and the latest available pituitary gland heights independently. Patients' current height information was collected by telephone interviews. We compared the pituitary height differences using paired t-tests and estimated the pituitary height trajectories within each sex by mixed regression models. Height-for-age Z-score was calculated for each patient using the WHO growth reference data for 5-19 years as reference. Most of the included participants were of male sex (75.6%) and over half were diagnosed at stage IV (58.4%). Among the 90 included participants, 89 had one repeated measurement of the pituitary height and 79 had two repeated measurements of the pituitary height. Seventy six of the 89 childhood NPC participants had reduced pituitary heights after radiation and accounted for 85.4% of the whole population. The means of the pituitary heights before and after radiotherapy were 6.4 ± 1.3 mm and 5.6 ± 1.2 mm (P < 0.001), respectively. The mean of height-for-age Z-score for childhood NPC cases was significantly below zero (-0.54, 95% CI = -0.74, -0.34). We concluded that childhood NPC cases had decreased pituitary heights and stunted linear growth after radiotherapy.

Radiation-Induced Growth Retardation and Microstructural and Metabolite Abnormalities in the Hippocampus

Cranial radiotherapy (CRT) increases survival in pediatric brain-tumor patients but can cause deleterious effects. This study evaluates the acute and long-term impact of CRT delivered during childhood/adolescence on the brain and body using a rodent model. Rats received CRT, either 4 Gy fractions × 5 d (fractionated) or a cumulative dose of 20 Gy (single dose) at 28 d of age. Animals were euthanized 1 d, 5 d, or 3.5 mo after CRT. The 3.5 mo group was imaged prior to euthanasia. At 3.5 mo, we observed significant growth retardation in irradiated animals, versus controls, and the effects of single dose on brain and body weights were more severe than fractionated. Acutely single dose significantly reduced body weight but increased brain weight, whereas fractionation significantly reduced brain but not body weights, versus controls. CRT suppressed cell proliferation in the hippocampal subgranular zone acutely. Fractional anisotropy (FA) in the fimbria was significantly lower in the single dose versus controls. Hippocampal metabolite levels were significantly altered in the single dose animals, reflecting a heightened state of inflammation that was absent in the fractionated. Our findings indicate that despite the differences in severity between the doses they both demonstrated an effect on cell proliferation and growth retardation, important factors in pediatric CRT.

ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context

This report provides a review of early and late effects of radiation in normal tissues and organs with respect to radiation protection. It was instigated following a recommendation in Publication 103 (ICRP, 2007), and it provides updated estimates of 'practical' threshold doses for tissue injury defined at the level of 1% incidence. Estimates are given for morbidity and mortality endpoints in all organ systems following acute, fractionated, or chronic exposure. The organ systems comprise the haematopoietic, immune, reproductive, circulatory, respiratory, musculoskeletal, endocrine, and nervous systems; the digestive and urinary tracts; the skin; and the eye. Particular attention is paid to circulatory disease and cataracts because of recent evidence of higher incidences of injury than expected after lower doses; hence, threshold doses appear to be lower than previously considered. This is largely because of the increasing incidences with increasing times after exposure. In the context of protection, it is the threshold doses for very long follow-up times that are the most relevant for workers and the public; for example, the atomic bomb survivors with 40-50years of follow-up. Radiotherapy data generally apply for shorter follow-up times because of competing causes of death in cancer patients, and hence the risks of radiation-induced circulatory disease at those earlier times are lower. A variety of biological response modifiers have been used to help reduce late reactions in many tissues. These include antioxidants, radical scavengers, inhibitors of apoptosis, anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, growth factors, and cytokines. In many cases, these give dose modification factors of 1.1-1.2, and in a few cases 1.5-2, indicating the potential for increasing threshold doses in known exposure cases. In contrast, there are agents that enhance radiation responses, notably other cytotoxic agents such as antimetabolites, alkylating agents, anti-angiogenic drugs, and antibiotics, as well as genetic and comorbidity factors. Most tissues show a sparing effect of dose fractionation, so that total doses for a given endpoint are higher if the dose is fractionated rather than when given as a single dose. However, for reactions manifesting very late after low total doses, particularly for cataracts and circulatory disease, it appears that the rate of dose delivery does not modify the low incidence. This implies that the injury in these cases and at these low dose levels is caused by single-hit irreparable-type events. For these two tissues, a threshold dose of 0.5Gy is proposed herein for practical purposes, irrespective of the rate of dose delivery, and future studies may elucidate this judgement further.

Postradiation therapy hypopituitarism

The increasing use of radiation treatment for head and neck cancers and other tumors, including pituitary adenomas, from the mid-20th Century onwards led to the recognition that pituitary function may be affected - often leading to some degree of pituitary insufficiency. Our knowledge is mostly based on observational or retrospective rather than randomized prospective studies. The various axes may be impacted at the hypothalamic or pituitary levels, or both. Some axes - the somatotropic and gonadotropic - appear to be especially vulnerable to radiation damage and may be affected quite early, whereas posterior pituitary function is rarely affected. Increased use of stereotactic radiosurgery, which focuses the radiation dose on the abnormal tissue, may be expected to reduce the impact on normal pituitary function, but such studies that are available are, as yet, relatively short term. Prospective studies of the effect of stereotactic radiosurgery on pituitary function would be valuable.

Pathophysiology of radiation-induced growth hormone deficiency: efficacy and safety of GH replacement

Radiation-induced growth hormone deficiency (GHD) is primarily due to hypothalamic damage. GH secretion by the pituitary may be affected either secondary to some degree of quantitative deprivation of hypothalamic input or, if the radiation dose is high enough, by direct pituitary damage. As a consequence, the neurosecretory profile of GH secretion in an irradiated patient remains pulsatile and qualitatively intact. The frequency of pulse generation is unaffected, but the amplitude of the GH pulses is markedly reduced. Over the last 25 years, the final heights achieved by children receiving GH replacement for radiation-induced GHD have improved; these improvements are attributable to refinements in GH dosing schedules, increased use of GnRH analogues for radiation-induced precocious puberty, and a reduced time interval between completion of irradiation and initiation of GH therapy. When retested at the completion of growth, 80-90% of these teenagers are likely to prove severely GH deficient and, therefore, will potentially benefit from GH replacement in adult life. Such long-term GH treatment in patients treated previously for a brain tumor means that critical and continuous surveillance must be devoted to the risk of tumor recurrence and the possibility of second neoplasms.

Seqüelas endócrinas da radioterapia no tratamento do câncer na infância e adolescência

A radioterapia resulta em endocrinopatias, osteoporose, obesidade e seqüelas neurológicas em pacientes tratados por câncer. A deficiência de GH é a complicação mais freqüente no eixo hipotálamo-hipofisário. A freqüência, prazo de surgimento e gravidade da deficiência de GH dependem da dose recebida durante a irradiação craniana, mas idade à radioterapia e fracionamento da dose também são variáveis importantes. Outras anormalidades do eixo hipotálamo-hipofisário são igualmente dose-dependentes. Baixas doses de irradiação induzem puberdade precoce ou avançada, enquanto altas doses provocam deficiência gonadotrópica. Complicações endócrinas secundárias à irradiação periférica, como distúrbios gonadais ou tireoidianos são descritos. Mesmo com secreção normal de GH, o crescimento pode ser comprometido por lesões ósseas após irradiação corporal total ou crânio-espinhal. Resultados melhores sobre a estatura final têm sido obtidos com reposição de GH em associação com o tratamento da puberdade precoce ou avançada. O objetivo desta revisão é a abordagem das seqüelas endócrinas tardias da radioterapia.

Long-term effects of radiation therapy on cognitive and endocrine function in children with leukemia and brain tumors

BACKGROUND

As the number of long-term survivors of childhood cancer has grown, it has become increasingly clear that central nervous system therapy may have serious long-term effects on cognition and endocrine function. These complications have been studied most extensively in children with brain tumors and leukemia.

REVIEW SUMMARY

Children with acute lymphoblastic leukemia previously treated with cranial irradiation are at risk for cognitive decline. Chemotherapy-only regimens, which rely on high-dose frequently administered methotrexate, are also associated with producing cognitive dysfunction. Children irradiated for brain tumors are even more vulnerable. Risk factors include perioperative morbidity, young age, large-volume high-dose cranial irradiation, supra-tentorial location of tumor, moyamoya syndrome, and leukoencephalopathy. Cognitive decline is progressive over at least a decade. The most common radiation-induced endocrinopathies are hypothyroidism and growth hormone deficiency. Treatment effects on growth are multifactorial and include growth hormone deficiency,spinal shortening, precocious puberty, undetected hypothyroidism,and poor nutrition. Fifty percent to 80% of children treated with craniospinal radiation for brain tumors will experience growth failure. In hopes of reducing neurotoxicity, current treatments limit the dose and volume of radiation while adding chemotherapy. Results have not been uniformly positive, however, and may increase toxicity in some cases.

CONCLUSIONS

The standard of care in 2004 is that children who have been treated for brain tumors and leukemia should be monitored for cognitive and endocrine dysfunction. Until effective non-neurotoxic treatment is identified, long-term effects assessments are essential to maximize the quality of life of survivors of childhood cancer.

Evaluating Survivors of Pediatric Cancer

The past 3 decades have seen tremendous improvements in the survival of children diagnosed with cancer, with the 5-year survival rate approaching 80%. This improvement in survival has resulted in a growing population of childhood cancer survivors. Use of cancer therapy at an early age can produce complications that may not become apparent until years later. Approximately two thirds of the survivors of childhood cancer experience at least one late effect and about one fourth experience a late effect that is severe or life-threatening, although psychosocial issues in survivors and family members are often underestimated and may be more prevalent. Long-term complications in childhood cancer survivors, such as impairment in growth and development, neurocognitive dysfunction, cardiopulmonary compromise, endocrine dysfunction, renal impairment, gastrointestinal dysfunction, musculoskeletal sequelae, and subsequent malignancies, are related not only to the specific therapy used but also may be determined by individual host characteristics. We review the known late effects in survivors of childhood in order to suggest reasonable starting points for the evaluation of specific long-term problems in this unique but growing population.

Endocrine outcome in children with medulloblastoma treated with 18 Gy of craniospinal radiation therapy

Craniospinal radiation therapy (CSRT) combined with chemotherapy results in significant endocrine morbidity. Between 1987 and 1990, a trial using 18 Gy was conducted to treat 10 young children with medulloblastoma. There were 7 survivors. We compared the endocrine outcome in these children (group 18 Gy) to that of a comparable group treated with conventional doses of CSRT that ranged from 23 to 39 Gy (group CD). Both groups had an identical history of chemotherapy and tumor stage and were treated with recombinant growth hormone therapy (rhGH). The mean age of group 18 Gy at diagnosis was 4.0 years, and rhGH treatment was initiated in 6 children at age 9.2 years. Group CD (12 children) was diagnosed at a mean age of 5.8 years and rhGH started in 11 children at a mean age of 9.6 years. The dose of rhGH used in both groups was identical (0.3 mg/kg/wk). For group 18 Gy, adult heights and sitting heights (a mean standard deviation score of -1.01 +/- 1.11 and -1.62 +/- 1.16, respectively) were statistically greater (P < 0.05) than those for group CD (mean standard deviation score of -2.04 +/- 0.83 and -3.16 +/- 1.43, respectively). Moreover, adult heights of group 18 Gy were not different from midparental heights, unlike group CD, whose adult heights were less than midparental heights (P < 0.0001). Of other endocrine sequelae, 10 patients of the CD group were hypothyroid, 3 had adrenal insufficiency, 3 had hypogonadism, and 2 had early puberty. In contrast, within group 18 Gy, only 1 was hypothyroid (P = 0.006) and 1 had early puberty. We conclude that endocrine morbidity was significantly reduced with 18 Gy CSRT in young children with medulloblastoma.

Characteristics of growth hormone therapy for pediatric patients with brain tumors in the National Cooperative Growth Study (NCGS) and from a survey of pediatric endocrinologists

Pediatric patients with brain tumors may have significant short stature secondary to growth hormone deficiency (GHD). This occurs as a result of impaired hypothalamic function due to tumor location, radiation therapy, surgery, or chemotherapy. The use of GH replacement therapy in this patient population is variable and somewhat unpredictable. We analyzed patient data from the National Co-operative Growth Study (NCGS) database and a survey completed by 19 members of the Pediatric Endocrine Alliance for Neuro Oncology Patients (PEANOP) to identify patterns of GH use in pediatric patients following treatment for brain tumors. From the NCGS database, we present demographic, dosing, and safety data. The PEANOP survey was examined to determine the percentage of patients receiving GH and the likelihood of treating these patients with GH following tumor treatment. The time to initiating GH replacement therapy was evaluated in 14 tumor types, as well as the contributing impact of the extent of tumor resection.

Growth hormone replacement therapy in children with leukemia in remission

We describe a patient with leukemia in remission for 7 years who developed growth hormone (GH) deficiency and was treated with recombinant human growth hormone (rhGH). We compare her growth with that of patients from the National Cooperative Growth Study (NCGS) database, 145 with leukemia in remission and 725 with idiopathic growth hormone deficiency (IGHD) on treatment with rhGH. We also review the literature on the risk of relapse of leukemia in similar patients. The patients with leukemia in remission from the NCGS database had a significantly lower change of mean height standard deviation score than that of IGHD patients in the first, second, and third year of rhGH treatment. The relapse rate of leukemia in patients treated with rhGH is between 0.8% and 2%. Starting rhGH therapy in patients with leukemia in remission and with GH deficiency at an adequate dosage and without undue delay would improve their growth response. Such therapy does not appear to increase the risk of leukemia.

Adult height after growth hormone (GH) treatment for GH deficiency due to cranial irradiation

BACKGROUND

The indications and factors affecting the growth in response to treatment with growth hormone (GH) of patients with cranial irradiation-induced GH deficiency remain unclear.

PROCEDURE

The adult heights of 56 patients treated with GH (0.4-0.6 U/kg/week) as daily sc injections were analysed. They had been given 18 or 24 Grays (Gy) cranial irradiation for leukemia (group 1, 26 cases), 50 +/- 1 Gy for various tumors (group 2, 13 cases), 46 +/- 1 Gy for retinoblastoma (group 3, 8 cases), or 34 +/- 2 Gy with spinal irradiation for medulloblastoma (group 4, 9 cases). Twenty- five of these 56 patients had early puberty and were also treated with gonadotropin-releasing hormone (GnRH) analog.

RESULTS

The standing (-1.0 +/- 0.2 in group 1, -0.7 +/- 0.3 in group 2, -1.1 +/- 0.3 in group 3, and -2.0 +/- 0.4 SD in group 4) and sitting (-1.8 +/- 0.2 in group 1, -0.4 +/- 0.4 in group 2, -1.2 +/- 0.4 in group 3, and -3. 4 +/-0.4 SD in group 4) adult heights were shor ter (P < 0.05 for standing and P < 0.001 for sitting heights) for group 4 than for each of the other groups. Of the 47 patients given cranial (and not craniospinal) irradiation, sitting adult height was shorter (P = 0. 02) and the difference between standing adult and target heights greater (P = 0.03) in those patients in whom puberty occurred at a normal age than in those treated with GnRH analog. Conclusion. The incomplete catch-up of growth seems to be mainly due to the reduction in sitting height of patients given spinal irradiation and in whom puberty occurred at a normal age. This suggests that GnRH analog treatment should be more widely used to treat children with early and/or rapidly progressing puberty after cranial irradiation.

Growth failure after treatment of pediatric brain tumors

OBJECTIVES

Primary brain tumors are the most common solid tumors that occur in childhood. With improved management of these tumors, there are more survivors with long-term sequelae of radiation and chemotherapy including growth failure. The aim of this study was to assess growth prospectively in children with nonpituitary-related primary brain tumors.

METHODS

Forty-one children 3.1 to 13.8 years of age diagnosed consecutively between 1989 and 1992 with a primary nonpituitary-related brain tumor were studied.

RESULTS

Of 34 prepubertal children, 14 (41%) were diagnosed as having growth hormone (GH) deficiency. All 14 children were treated with cranial irradiation. During the first year from completion of brain tumor therapy, the annual height velocity of those children confirmed subsequently as being GH-deficient was 3.06 +/- 1.19 cm compared with 5.29 +/- 2.21 cm for those who were not GH-deficient. During the second year, the annual height velocity was 3.29 +/- 1.14 cm per year for the GH-deficient group compared with 5.48 +/- 1.24 cm per year for the non-GH-deficient group. All children with GH deficiency received cranial irradiation and chemotherapy. Two of 34 children developed precocious puberty. Primary hypothyroidism was diagnosed in 6 of 41 children (12%).

CONCLUSION

We conclude that GH deficiency and primary hypothyroidism are common after cranial irradiation and chemotherapy for nonpituitary-related brain tumors. Linear growth appears to reflect GH status accurately in children with brain tumors. Precise auxologic evaluation is simple and noninvasive and may reflect more accurately GH status than provocative GH testing. These findings reflect the need for prospective growth monitoring of children with nonpituitary-related brain tumors treated with cranial irradiation and chemotherapy. Early diagnosis of GH deficiency facilitates early initiation of GH therapy and optimization of final height.

Growth hormone deficiency following radiotherapy for orbital and parameningeal sarcomas

Growth hormone deficiency (GHD) is a recognized late effect of successful treatment of tumors requiring cranial irradiation. Growth after treatment was assessed in 16 patients with sarcomas of the orbital and parameningeal regions. Median age at diagnosis was 6.35 years and median follow-up was 7.2 years. Treatment consisted of combination chemotherapy and radical radiotherapy, conventionally fractionated with a median dose 4500 cGy; the hypothalamic/pituitary region received a median dose of 4163 cGy. Height was measured every 6 months and 13/16 patients underwent tests of GH function. At GH testing median height standard deviation score (SDS) was -0.7, a median decrease of -0.55 since tumor diagnosis. Seven patients were treated with human GH (hGH) at a median of 3.7 years from tumor diagnosis and followed for a median of 2.7 years. Treatment with hGH resulted in a median increase in height SDS of 0.9. Careful surveillance with timely introduction of GH replacement is required for treatment of GHD following treatment of orbital and parameningeal sarcomas.

[Late effects of radiotherapy on the neuroendocrine system]

When the hypothalamic-pituitary axis (HPA) is included in the treatment field in children and adults, a variety of neuroendocrine disturbances are more common than has been appreciated in the past. Clinical damage to the pituitary and thyroid glands usually occurs months to years after treatment, and is preceded by a long subclinical phase. Primary brain tumors represent the largest group of malignant solid tumors in children. The survival rates of 50% reported in the literature are achieved at the expense of late occurring effects. Radiation-induced abnormalities are generally dose-dependent. Growth hormone deficiency and premature sexual development can occur at doses as low as 18 Gy in conventional fractionation, and is the most common neuroendocrine problem in children. In patients treated with > 40 Gy on the HPA, deficiency of gonadotropins, thyroid stimulating hormone, and adrenocorticotropin can be found. Following high-dose radiotherapy (> 50 Gy), hyperprolactinemia can be seen, especially among young women. Most neuroendocrine disturbances that develop as a result of HPA can be treated efficiently, provided that an early detection of these endocrine dysfunctions abnormalities is done.

Endocrine late effects of childhood cancers

Long-term survival in children with cancer has increased markedly in the past 15 years. However, impaired linear growth and thyroid dysfunction that vary according to the age at diagnosis and treatment and to the dose and duration of radiation and chemotherapy have been described in these patients. The impact of cranial irradiation on the hypothalamic-pituitary-adrenal axis and on pubertal maturation has been less well studied. A positive correlation between the age at diagnosis and the age at onset of puberty in children who have been treated with high-dose cranial radiation therapy for central nervous system (CNS) tumors has been found recently. Frank adrenal insufficiency is uncommon after high-dose CNS irradiation, but alterations in the hypothalamic-pituitary-adrenal axis do occur. Assessments of the effects of newer modes of radiation therapy such as hyperfractionated craniospinal radiation suggest a lower incidence of primary hypothyroidism in the long term.

Growth and neuroendocrine dysfunction following therapy for childhood cancer

Poor linear growth and short adult stature are common complications following successful treatment of childhood cancer. Although several factors contribute to the impaired growth of these patients, growth potential is most reduced following radiotherapy to the head or spine. Younger age at treatment and female sex seem to be significant and independent risk factors for short adult height. Early diagnosis and timely therapy of the endocrine sequelae of cancer treatment (i.e., GH deficiency, hypothyroidism, and precocious puberty) ensure that these individuals will reach their optimum growth potential. For patients exposed to high-dose radiotherapy (> 35-40 Gy) to the region of the hypothalamus and pituitary gland, a variety of neuroendocrine abnormalities in addition to GH deficiency and early sexual development may occur, including deficiencies of LH/FSH, TSH, and ACTH as well as hypersecretion of prolactin. Because these problems may develop many years after irradiation, patients at risk for neuroendocrine disturbances require long-term endocrine follow-up.

Growth hormone treatment in irradiated children with brain tumors

We assessed the efficacy of GH treatment in 25 GH deficient patients irradiated for brain tumors (eight with glioma cranio-irradiated, eleven with medulloblastoma and six with ependymoma craniospinal-irradiated). We administered GH at doses of 0.6-0.9 IU/kg/week for one to three years at least two years after diagnosis of the tumor. We assessed the efficacy of the treatment each year by comparing the values of height velocity over bone age and change in the ratios progression of chronological age/progression of bone age and progression of statural age/progression of bone age. The treatment promoted satisfactory growth; better results were obtained in patients with glioma, who received cranial irradiation only, than in those with medulloblastoma or ependymoma, who received spinal irradiation as well. Moreover, the growth prognosis improved, especially in the cranio-irradiated patients. In our series of patients four presented tumor recurrence; these results did not differ significantly from those in irradiated patients with cerebral tumors who were not treated with GH.

Spontaneous growth and response to growth hormone treatment in children with growth hormone deficiency and idiopathic short stature

Isolated idiopathic growth hormone deficiency (GHD) and idiopathic short stature (ISS) can be difficult to distinguish, but the therapeutical consequences are different. In this report the data on final height of untreated and treated children with GHD and ISS are reviewed. Untreated GH-deficient individuals who underwent spontaneous puberty (22 male, 14 female patients) reached a mean final height of 4.7 SD (range 3.9 to 6.0) below the population's mean. If puberty was induced (19 male patients), mean final height SD score (SDS) was -3.1. Traditional regimens of GH administration (2-4 injections/wk) in 236 children (184 boys, 52 girls) with GHD and spontaneous puberty resulted in a final height SDS of -2.8 (range -1.5 to -4.7). In 190 children in whom puberty was induced (139 boys, 51 girls) mean final height was -1.6 (range - -1.1 to -2.4). The mean gain in final height SDS is therefore estimated at 1.5-2.0 in average cases, and 3.5 in extreme cases. Preliminary data suggest that on present regimens mean final height may approach target height. In untreated boys with ISS the mean final height was 2-5 cm lower than that predicted before puberty, whereas in girls it was almost equal to the prediction. After GH treatment the mean final height was 0.4-3.0 cm higher than the predicted adult height, which results in an average net gain in final height SDS of approximately 0.5-0.8 (3-5 cm).

Effect of chemotherapy on growth

Growth restriction has been demonstrated clearly following the treatment of childhood malignancies, even in the absence of irradiation to the hypothalamic-pituitary axis. The use of CT and spinal irradiation in the original treatment of brain tumours has a marked effect on growth. This effect is most profound in children who have received both treatments and cannot be overcome using GH therapy at conventional doses.

Growth and puberty after growth hormone treatment after irradiation for brain tumours

The impact of treatment with either cranial or craniospinal irradiation with or without cytotoxic chemotherapy for a brain tumour distant from the hypothalamic-pituitary axis was assessed in 29 children who had reached final height. All had received growth hormone treatment for radiation induced growth hormone deficiency. Final height, segmental growth during puberty, and duration of puberty were studied. Both craniospinal irradiation and the use of chemotherapy resulted in a significant and equal reduction in final height; this effect in those children who received both craniospinal irradiation and chemotherapy was additive. The degree of height loss was related to the age at irradiation, the most profound effect on final height occurring in the youngest at irradiation. The mean duration of puberty from G2-G4/B2-B4 (1.97 years) was not significantly different from the duration of puberty in normal children. Growth hormone increases growth velocity in children with radiation induced growth hormone deficiency but their final height is significantly less than their mid-parental height. The use of spinal irradiation and chemotherapy in the original treatment of brain tumours has a marked effect on growth which is not overcome with the use of growth hormone treatment in current doses. Early puberty of normal duration contributes to poor growth.

Chronic neuroendocrinological sequelae of radiation therapy

A variety of neuroendocrine disturbances are observed following treatment with external radiation therapy when the hypothalamic-pituitary axis (HPA) is included in the treatment field. Radiation-induced abnormalities are generally dose dependent and may develop many years after irradiation. Growth hormone deficiency and premature sexual development can occur following doses as low as 18 Gy fractionated radiation and are the most common neuroendocrine problems noted in children. Deficiency of gonadotropins, thyroid stimulating hormone, and adrenocorticotropin are seen primarily in individuals treated with > 40 Gy HPA irradiation. Hyperprolactinemia can be seen following high-dose radiotherapy (> 40 Gy), especially among young women. Most neuroendocrine disturbances that develop as a result of HPA irradiation are treatable; patients at risk require long-term endocrine follow-up.

Long-term sequelae of therapy for childhood acute lymphoblastic leukaemia

Childhood ALL has provided the model for basic therapeutic principles in the past and now provides the model for late effects studies. Common threads which run throughout the literature in this area of clinical research are the importance of young age with increased vulnerability to long-term treatment induced sequelae and the relatively large contribution of radiation as compared with chemotherapy in the pathogenesis of adverse sequelae. Previous retrospective studies of long-term childhood ALL survivors focused on neuropsychologic changes and anatomic changes in the CNS after cranial irradiation. More recent retrospective studies have made the following new observations: (i) the high frequency of significant short adult stature in those less than 6 years of age at diagnosis who received 24 Gy cranial irradiation; (ii) actuarial risk of 2.5% of developing a second malignancy with approximately one-half of secondary malignancies occurring in the CNS in children 5 years of age or less who received cranial irradiation; (iii) the association of secondary ANLL with epipodophyllo-toxin use, and (iv) delayed cardiac toxicity despite anthracycline dosage reduction. Current therapy regimens, especially in high-risk patients, are both more successful and more intensive than those used in the past. While it will be another decade before many of the long-term sequelae begin to emerge, one can anticipate, based on current experience, some of the problems that will occur.

Conventional and nonconventional uses of growth hormone

Although GH has been available as a therapeutic agent for the GH-deficient child for more than 30 years, the conditions of its use have yet to be optimized. The availability of biosynthetic material has provided researchers with the opportunity to develop the protocols necessary to begin to finally answer the most fundamental questions pertaining to dose, frequency, and duration of treatment. It has also permitted the initiation of prospective trials in a large number of conditions that result in childhood short stature, with the expectation that some or many of them will be treated effectively and safely. Finally, it has opened the door to an entire spectrum of potentially new uses of GH and other growth factors for so-called nonconventional indications. That these have implications that range from the short-term rapid healing of a burn graft site, to the more efficient induction of ovulation, to the long-term preservation of lean body mass has excited the interest of investigators in many fields of medicine and physiology. Thus, the recent progress reported in this paper is really the beginning of the new research that will take place with GH and growth factors.

Irradiation-induced growth failure

GH deficiency, skeletal disproportion and early or precocious puberty may complicate irradiation to the head or axial skeleton in childhood. Certain cohorts of children are at particular risk, including those irradiated for brain tumours and various haematological malignancies. Both GH deficiency and impaired spinal growth may result in short stature, whereas the occurrence of early puberty in association with GH deficiency reduces the time available for GH therapy. The age of the child at irradiation is critical in that, in younger children, the central nervous system is more radiosensitive, the severity of the subsequent skeletal disproportion is greatest and the onset of puberty earliest. It is the very young craniospinally-irradiated child who is most at risk of extreme short stature.