Irradiation-induced growth hormone deficiency: blunted growth response and accelerated skeletal maturation to growth hormone therapy

Growth and growth hormone therapy of children treated for leukaemia

A total of 37 children (24 male, 13 female) who had been treated for leukaemia with chemotherapy and 24 Gy cranial irradiation, and who were disease free for at least 18 months, were commenced on somatrem at a mean of 7.6 years (range, 4.8-12.1 years) after leukaemia diagnosis because of growth rate below the 25th centile for bone age. Peak GH response to provocation (exercise, arginine, insulin hypoglycaemia) was less than 20 milliunits/litre in 27 children (deficient group) and 20 milliunits/litre or more in 10 children (non-deficient group). The mean height SD decrease from diagnosis of leukaemia to commencement of somatrem was 1.98, 86% of the children decreasing by more than 1 SD. Those who were tall for age at leukaemia diagnosis and females were more severely affected. Mean (+/- SD) height velocity increased on somatrem from 2.7 +/- 1.1 to 6.6 +/- 2.2 cm/year during the first 6 months (n = 25), and to 6.0 +/- 1.7 cm/year during the first 12 months (n = 19). No difference in growth response was seen between the sexes or between the deficient and non-deficient groups. Catch-up growth occurred for the first 6 months only. It is concluded that children with a low growth rate after treatment of leukaemia should be considered for GH therapy irrespective of the results of GH provocative tests.

Effects of puberty on bone age maturation in a girl after medulloblastoma therapy

BACKGROUND

Craniospinal radiotherapy for malignant brain tumors can result in a variety of neuroendocrine disturbances, among which are the development of growth hormone deficiency and early puberty, which can markedly reduce adult height.

METHODS

The authors report the case of a girl who received craniospinal radiotherapy for a medulloblastoma at the age of 3.4 years. At 9.1 years, growth hormone therapy was started, and spontaneous onset of puberty (Tanner stage B2) occurred at age 10.3 years. Interval until menarche was short, at only 0.9 years.

RESULTS

Although chronologic age at appearance of Tanner stages was within the normal range, the patient showed a rapid acceleration in skeletal maturation, resulting in adult short stature.

CONCLUSION

Bone age seems to be a more precise parameter for biologic maturation in some patients after craniospinal irradiation than is clinical assessment of pubertal stages. Thus, if progression of bone age and decreasing final height predictions are noted, puberty should be stopped with gonadotropin-releasing hormone analogs, even if pubertal development seems to be adequate for chronologic age, because this increases the remaining time for growth hormone treatment.

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.

Bilateral temporal bone encephaloceles after cranial irradiation. Case report

Irradiation of the central nervous system may cause significant morbidity, including endocrine dysfunction and intellectual impairment. The authors report a case of bilateral temporal bone encephaloceles in a 21-year-old man who had received prophylactic central nervous system irradiation for acute lymphocytic leukemia in early childhood. Endaural encephaloceles are uncommon, and most occur as a complication of mastoid surgery. The etiology, clinical features, radiological diagnosis, and surgical treatment of temporal bone encephaloceles are discussed.

Long-term complications following bone marrow transplantation in children

Seventeen children who underwent bone marrow transplantation (BMT) between 1975 and 1985 and survived for more than 2 years were evaluated for growth and development. The patients had a follow up of 2.1-13.1 years. Prior to transplant, children with malignancy had received multi-agent chemotherapy and nine had also received central nervous system irradiation. Transplant preparation for malignancy (group 1; n = 13) included high-dose cyclophosphamide (CPA) 120-200 mg/kg and total body irradiation (TBI) 10-13.2 Gy, whereas conditioning for non-malignant disorders (group 2; n = 4) included high-dose CPA 200 mg/kg with or without busulphan. Patients in group 1 showed a steady decline in height velocity following initial chemotherapy and cranial irradiation and the decline was even greater following BMT. Growth hormone (GH) deficiency developed in eight of nine children tested, hypergonadotrophic hypogonadism developed in 11 who reached puberty, thyroid hormone abnormalities were encountered in four out of 10 tested and 11 of 13 developed cataracts. Patients in group 2 did not show decline in linear growth rate, thyroid hormone abnormalities or cataracts after BMT. The only child tested had normal GH levels and the two patients who reached puberty showed delayed but complete gonadal recovery. Our data demonstrate that TBI leads to significant late effects on growth and gonadal function. Contrary to previous reports, a high incidence of cataract formation is observed after fractionated TBI. Conditioning regimens TBI should be considered in children undergoing BMT.

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.

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

Growth hormone (GH) deficiency (GHD) induced by cranial irradiation has become a frequent indication of hGH substitutive therapy. This study analyses the growth response to hGH therapy and the factors involved in the decrease in growth velocity observed after cranial irradiation. One hundred children (61 boys and 39 girls) given cranial radiation for pathology distant from the hypothalamo-pituitary area were studied. Fifty-six of them received hGH therapy for GHD resulting in decreased growth velocity. The initial annual height gain in the cranial-irradiated group was comparable to that of patients treated for idiopathic GHD; additional spinal irradiation significantly reduced the growth response. Twenty-eight hGH-treated patients reached final heights which were compared to those of 2 untreated irradiated groups, one with GHD (n = 27) and the other with normal GH secretion (n = 17). The height SD score changes observed in hGH therapy were +0.3 in the cranial (n = 10) and -1.2 SD in the craniospinal (n = 18) groups. GH deficiency had contributed to a mean height loss of 1 SD and spinal irradiation to a loss of 1.4 SD. The small effect of hGH therapy on final height is probably linked to the small bone age retardation at onset of hGH therapy and to the fact that irradiated children entered puberty at a younger age in terms of chronological age (10.6 +/- 0.3 yr in girls and 11.0 +/- 0.3 yr in boys) and bone age (9.6 +/- 0.4 yr in girls and 12.6 +/- 0.3 in boys) than the idiopathic GHD patients. These data suggest that the results of hGH therapy in irradiated children might be improved with higher and more fractionated hGH doses and, in some patients, by delaying puberty using luteinizing hormone releasing hormone analogs.

Radiation and hypothalamic-pituitary function

In adults, hypopituitarism is a common consequence of external radiotherapy. The clinical manifestations may be subtle and develop insidiously many years after radiotherapy. Anterior pituitary deficiencies can therefore only be detected by regular testing, including dynamic tests of GH and ACTH reserve. Although the deficiencies most commonly develop in the order GH, gonadotrophins, ACTH then TSH, this sequence may not be predictable in an individual patient and comprehensive testing is therefore required. The tests should ideally be performed annually for at least 10 years after treatment or until deficiency has been detected and treated. It is not only the patients with pituitary disease who are at risk of developing hypopituitarism after radiotherapy. Any patient who receives a total dose of irradiation of 20 Gy or more to the hypothalamic-pituitary axis is at risk of hypopituitarism, although the threshold dose may be lower than this. This is particularly important in the long-term survivors of malignant disease in whom endocrine morbidity may be relatively common and in whom this can be easily treated, with consequent improvement in quality of life. Whilst patients who receive a high total dose of irradiation are at increased risk of developing multiple deficiencies, a higher fraction size also increases the risk of anterior pituitary failure. There is good evidence that the earliest damage to the hypothalamic-pituitary axis after external radiotherapy is at the level of the hypothalamus. However, patients who undergo pituitary ablation with interstitial radiotherapy or heavy particle beams are likely to sustain direct damage to the pituitary. In these patients, the sequence in which individual pituitary hormone deficiencies develop is generally the same as that observed with the hypothalamic damage after conventional external radiotherapy. The increasing use of radiotherapy as a means of treatment for malignant disease means that new groups of patients with potential for endocrine dysfunction are emerging. Whole body irradiation in the preparation for bone marrow transplant is one such treatment and although hypothalamic-pituitary damage appears to be confined to GH deficiency in children, longitudinal experience is limited to date, particularly in adults. The treatment of malignant disease in childhood is of particular importance in terms of the delayed endocrine sequelae. The hypothalamic-pituitary axis may not be the only endocrine tissue damaged by treatment in these patients and management is therefore more complicated. In the growing child, the potential association of growth hormone deficiency, gonadal failure or premature puberty and thyroid dysfunction mean that expert endocrine supervision is essential for optimum long-term outcome.

Astrocytoma in childhood: survival and performance

Seventy-nine children (35 female, 44 male) with proven or presumed astrocytoma were treated from 1967 to 1987. The tumors were supratentorial located in 24 children, cerebellar in 21 children, and pontine in 34 children. If possible, a radical tumor resection (4%), a subtotal tumor resection (51%), or a biopsy (8%) was performed. The predominant pathological Kernohan grading for the supratentorial, cerebellar, and pontine located tumors were grades II, II, and IV respectively. Histology was unknown in 15 out of 34 pontine tumors and in 1 out of 24 supratentorial tumors. Low-graded tumors (46%) were irradiated with a local field (1.8/45-50 Gy) and children with high-graded tumors (34%) received a total brain irradiation (1.8/40 Gy) followed by a boost irradiation (10 Gy) in 5 or 6 fractions. Overall 1-, 5-, and 10-year survivals of children with supratentorial, cerebellar, and pontine located tumors were 96%-91%-46%, 95%-95%-95%, and 35%-20%-20% respectively. For all tumor locations, 77% of deaths occurred within 2 years of treatment. The performance status of both children with supratentorial and cerebellar astrocytoma showed an increase during the first year of treatment and then stabilized on a rather high level (mean performance after 5 years of 60% and 70% respectively). Children with pontine tumors showed a steep decrease in performance status during the first year of treatment and then stabilized on a low level (mean performance after 5 years of 15%). In our study, children with supratentorial astrocytoma showed improvement in both survival and performance status after irradiation following surgical removal of the tumor.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate metabolism on high dose growth hormone therapy in children treated for leukaemia

The effect on carbohydrate metabolism of a high dose growth hormone (GH) regimen (1.2 U/kg per week) was assessed on 24 children who had previously been treated for leukaemia. Sixteen patients received high dose GH and eight patients received a conventional dose of GH (0.6 U/kg per week). Oral glucose tolerance tests (OGTT) were performed at baseline and after 3 months of treatment with GH. For the entire group between 0 and 3 months, there was a significant increase in mean (and standard deviation) fasting plasma glucose (0.3 +/- 0.6 mmol/L), fasting insulin level (11 +/- 26 mU/L), and 2 h insulin level (20 +/- 40 mU/L). One patient, who received a conventional dose of GH, developed substantial carbohydrate intolerance. For the entire group, there was no change in response to a carbohydrate load at 3 months as measured by the area under the plasma glucose or insulin curve. There was no significant difference between conventional and high dose groups at 3 months as assessed by these parameters. This study demonstrates that a higher dose of GH may be used in these children in an attempt to improve their final height, without increased risk of carbohydrate intolerance in the short term.

Improved growth response to GH treatment in irradiated children

The growth response to two years of GH treatment was studied in fifteen children after radiotherapy for a cranial tumor. The growth response was compared to that of short children (-2 SD) and that of children with idiopathic growth hormone deficiency (GHD) of similar ages. All children were treated with hGH 0.1 IU/kg/day s.c.; which is a higher dose and frequency than previously reported for irradiated children. On this protocol the growth rate increased 5.0 +/- 0.5 cm/y (mean +/- SEM) the first year and 3.8 +/- 0.7 cm/y the second year compared to the growth rate the year before GH-treatment. Although the net gain in growth was higher than previously reported, the first year growth response was significantly reduced (p less than 0.05) compared to that of GHD-children (7.6 +/- 0.5 cm/y) but exceeded (p less than 0.05) that of short children (3.4 +/- 0.3 cm/y). The median spontaneous 24 h-GH secretion was 209 mU/l in the short children, 52 mU/l in the irradiated children and 16 mU/l in the idiopathic GHD children. Thus the growth increment varied inversely to the spontaneous GH secretion observed in the three groups.

Late effects of antileukemic treatment

Increasing numbers of childhood ALL survivors have increased the need to assess the physical and psychosocial functioning of this group in a careful manner. This article reviews data on the frequency and types of second malignancies, structural and functional changes in the central nervous system, endocrine effects on growth and reproduction, and psychosocial aspects of development. Most long-term survivors of ALL do not have serious or life-threatening medical problems; however, medical and psychosocial problems may not be insignificant and may require coordinated management over prolonged periods.

Growth response to growth hormone therapy following cranial irradiation

The growth response to growth hormone (GH) therapy has been studied in 12 children who received irradiation to the cranium alone either for brain gliomas, distant from the hypothalamic-pituitary axis, or as prophylaxis against CNS leukaemia. Seven children have completed GH treatment (mean duration 4 years) and five are presently on GH (mean duration 1.2 years). This response has been compared to that seen in 14 children with isolated idiopathic GH deficiency (IGHD), following GH therapy. Before treatment, the cranially irradiated patients (C-PRGHD) had higher standard deviation scores (SDS) for standing height, sitting height and leg length, and less bone age (BA) retardation, but started treatment at a similar age, and with a similar pre-treatment growth velocity and GH peak to standard provocative tests, compared to IGHD patients. GH produced a significant and similar increase in growth velocity (cm/year and SDS for BA) over the first 2 years' treatment in both groups. However C-PRGHD patients entered puberty and thus completed growth earlier than the IGHD group. As a result, cranially-irradiated children showed no change in height SDS with GH therapy, compared to catch-up growth in IGHD. Nevertheless, GH has enabled C-PRGHD patients to maintain their centile position and to achieve a more acceptable final height.

Growth response to growth hormone therapy following craniospinal irradiation

Nineteen (12 male, 7 female) children, who have received craniospinal irradiation for the treatment of a brain tumour distant from the hypothalamic-pituitary axis, resulting in growth hormone (GH) deficiency (CS-PRGHD), have been treated with GH. Eight have completed growth. Comparison has been made with the growth of seven untreated children, whose heights and growth rates at presentation were normal despite GH deficiency secondary to irradiation. GH produced a significant increase in growth velocity over the first 3 years' treatment in CS-PRGHD patients with a mean first year increment of 3 cm/year. Patients, treated to completion of growth, showed a significant increase in leg length standard deviation (SD) score (delta SDS + 0.2) compared to that of the untreated (delta SDS - 0.9) (P less than 0.05). Sitting height SD scores decreased irrespective of GH therapy (by -1.7 for the treated and -2.2 for the untreated). The onset of puberty in the irradiated patients occurred at a mean bone age of 10.7 years in males and 9.9 years in females. This limited the time available for GH therapy. These factors resulted in a decrease in standing height SDS of 0.9 at completion of GH therapy in CS-PRGHD, but a decrease of 1.7 in those not treated with GH. Thus GH therapy failed to induce "catch-up" growth in irradiated patients, but it did prevent further loss of adult stature, with a mean final height SD score of -3.4 in CS-PRGHD patients.

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.

Recent developments in pediatric neuro-oncology

Although brain tumors represent the second most common malignancy in childhood, there are only 1200 to 1500 children diagnosed with brain tumors each year in the US. Approximately 50% of these children are treated at university or cancer treatment centers. Thus, therapeutic trials by default rather than design have been restricted to small numbers of patients. Information on histopathologic groupings, incidence of various tumor types according to age, general treatment trends and survival statistics are available from the Surveillance, Epidemiology, and End Results (SEER) registries of the National Cancer Institute. Although survivals in brain tumor cancers are worse than in other forms of childhood cancer, treatment advances in surgery, radiation and chemotherapy have significantly improved survivals in at least one brain tumor of childhood, medulloblastoma. Ironically, this treatment may have significant long-term adverse effects on intellect, endocrine function, and on the development of second malignancies. Prompt recognition of these delayed effects is of clinical importance, as some effects are amenable to treatment and others may be prevented by careful monitoring of drug and radiation administration.