Dosimetry and growth hormone deficiency following cranial irradiation of childhood brain tumors

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.

The Predictive Value of Insulin-Like Growth Factor 1 in Irradiation-Dependent Growth Hormone Deficiency in Childhood Cancer Survivors

BACKGROUND

The literature contains conflicting reports on the value of low insulin-like growth factor 1 (IGF-1) levels in predicting radiation-induced growth hormone (GH) deficiency (GHD) in childhood cancer survivors (CCS). These reports often involve small samples of patients who have received irradiation or mixed cohorts including non-irradiated subjects.

OBJECTIVE

We undertook an analysis of the predictive value of low IGF-1 in CCS at risk for GHD after cranial radiotherapy involving the hypothalamic-pituitary (HP) area in a large single-centre cohort.

METHODS

We performed a retrospective analysis on 158 CCS diagnosed with GHD between January 1, 2003 and October 31, 2017 and identified 117 patients who received radiation for tumours not direct ly involving the HP area.

RESULTS

In this cohort, IGF-1 levels <-2 standard deviation scores (SDS) had a sensitivity of 31.9% for GHD; however, they were statistically more frequent (p = 0.0023) and had a higher sensitivity (45.6%) among patients with severe GHD. At final height reassessment, IGF-1 <-2 SDS had a sensitivity of 35.0% for GHD, but a positive predictive value of 100%. Finally, pretreatment IGF-1 values showed no correlation with the number of impaired pituitary hormonal axes in patients with multiple pituitary deficiencies.

CONCLUSIONS

IGF-1 levels <-2 SDS showed a low sensitivity at predicting radiation-induced GHD both in childhood and in adulthood, but a high positive predictive value for GH status at final height reassessment.

Dose-Constraint Model to Predict Neuroendocrine Dysfunction in Young Patients With Brain Tumors: Data From a Prospective Study

PURPOSE

We report on a possible dose-constraint model to predict long-term neuroendocrine dysfunction after cranial irradiation in children and young adults with benign and low-grade brain tumors treated with stereotactic conformal radiation therapy (RT) in a prospective clinical trial.

METHODS AND MATERIALS

Patients treated with stereotactic conformal RT (54 Gy in 30 fractions) were included for analysis if their co-registered planning computed tomography and magnetic resonance imaging scans were available, along with baseline and post-RT endocrine assessment for at least 2 years. The hypothalamus-pituitary axis (HPA) was contoured on the fused computed tomography-magnetic resonance imaging data set. Worsening of endocrine function was defined biochemically as a new onset endocrine deficit or worsening of preexisting endocrine deficit. Dosimetric indices of HPA, extracted using cumulative dose-volume histograms, were correlated with worsening endocrine function using logistic regression analysis.

RESULTS

A total of 51 patients (median age: 13 years; range, 5-25 years) were included. Worsening post-RT endocrine levels were seen in 27 of 51 patients (47%). Growth hormone was the most commonly affected (70%), followed by cortisol (44%), gonadotropin (40%), and thyroxine (7%). The mean of the maximum and minimum doses to HPA was 42.1 Gy and 35.7 Gy, respectively. For patients with worsening endocrine levels, the mean maximum dose to HPA was 46.6 Gy compared with 36.5 Gy in patients with stable functions. The mean minimum dose to HPA was also higher (40.5 Gy vs 29.6 Gy) in patients with endocrine dysfunction. Logistic regression analysis identified the volume of HPA receiving 50% of the prescribed dose as the only statistically significant parameter predicting endocrine dysfunction. A dose of ≥27 Gy to any volume of HPA was associated with a 4-fold increase in risk of endocrine dysfunction (odds ratio: 4.05; 95% confidence interval, 1.07-15.62; P = .038).

CONCLUSIONS

Our prospective longitudinal study demonstrates the feasibility of HPA avoidance using modern, high-precision, conformal RT techniques and correlates HPA dosimetry with neuroendocrine dysfunction. We suggest restricting HPA doses to <27 Gy to minimize the risk of post-RT neuroendocrine deficits.

Diagnosis of GH Deficiency as a Late Effect of Radiotherapy in Survivors of Childhood Cancers

BACKGROUND

Limited guidance exists for selecting a laboratory method for diagnosing GH deficiency (GHD) when it occurs as a late effect of radiotherapy in childhood cancer survivors (CCSs).

METHODS

We searched Medline, Embase, Cochrane Central Register of Controlled Trials and Database of Systematic Reviews, and Scopus for studies evaluating GHD that used IGF-1 or IGF-binding protein 3 (IGFBP-3) measurements compared with GH dynamic testing.

RESULTS

We included 15 studies [IGF-1 (8 studies) and IGFBP-3 (7 studies)] enrolling 477 patients. Comparator tests varied widely. Overall, both IGF-1 and IGFBP-3 had suboptimal diagnostic accuracy but were strongly correlated. The use of both tests simultaneously in the same cohort did not improve the diagnostic accuracy. Despite high variability in the testing protocols, dynamic tests remained the most accurate for appropriately identifying patients with GHD. The insulin tolerance test (ITT) appears to be the most accepted reference test when used alone or in combination with arginine; however, standardized testing strategies among practice groups are absent. GHRH and arginine stimulation performed almost similarly to the ITT; however, in one study GHRH with arginine stimulation had 66% sensitivity and 88% specificity compared with the ITT. Insufficient data were available to assess the accuracy of serial GH testing (nocturnal or over 24 hours).

CONCLUSION

The diagnostic accuracy of various dynamic tests for GHD in CCSs appears to follow the same patterns as those in non-CCSs. Interpreting GHRH stimulation is a challenge given the primarily hypothalamic dysfunction in CCSs. IGF-1 and IGFBP-3 perform poorly in this population.

Pediatric Salivary Cancer: Epidemiology, Treatment Trends, and Association of Treatment Modality with Survival

Objective To characterize the epidemiology of pediatric salivary cancer and associate patient, tumor, and treatment factors with treatment modality and survival. Study Design Cross-sectional analysis. Setting US national database. Subjects and Methods We identified 588 patients 19 years or younger diagnosed with salivary cancer in the National Cancer Database 2004-2013. We characterized patient, tumor, and treatment factors as proportions and associated these factors with treatment modality and overall survival via multivariable logistic regression and multivariable Cox proportional hazards regression, respectively. Results In total, 588 patients were included. Mucoepidermoid carcinoma was identified in 234 of 588 patients (40%) and acinar cell carcinoma in 215 of 588 (37%). Parotid tumors were seen in 504 (86%) of patients. Surgery alone was used to treat 351 (60%) of patients; surgery plus adjuvant radiation was used to treat 145 (25%). Overall 5-year survival was 93%. Controlling for patient and tumor characteristics, treatment with surgery and radiation vs surgery alone was associated with improved overall survival (hazard ratio [HR] = 0.15; 95% confidence interval [CI], 0.02-0.92; P = .041). High tumor grade was associated with decreased overall survival (HR = 33.17; 95% CI, 5.89-186.8; P < .001). Treatment with surgery plus radiation remained associated with improved overall survival in the subset of patients with high tumor grade (HR = 0.12; 95% CI, 0.02-0.64; P = .014). Conclusion Tumor grade is an important predictor of survival in pediatric patients with salivary gland cancer. Surgery plus adjuvant radiation vs surgery alone is associated with improved overall survival and may be considered for high-risk patients, particularly those with high-grade tumors.

Efficacy of Stereotactic Conformal Radiotherapy vs Conventional Radiotherapy on Benign and Low-Grade Brain Tumors: A Randomized Clinical Trial

Importance

Evidence for application of stereotactic and other conformal radiotherapy techniques in treating brain tumors is largely based on data derived from dosimetric, retrospective, or small prospective studies. Therefore, we conducted a randomized clinical trial of stereotactic conformal radiotherapy (SCRT) compared with conventional radiotherapy (ConvRT) evaluating clinically meaningful end points.

Objective

To compare neurocognitive and endocrine functional outcomes and survival at 5 years in young patients with residual and/or progressive benign or low-grade brain tumors treated with SCRT and ConvRT techniques.

Design, Setting, and Participants

This phase 3 randomized clinical trial enrolled 200 young patients (ages 3-25 years) with residual or progressive benign or low-grade brain tumors at a single center between April 2001 to March 2012. Patients were randomly allocated (1:1) to either SCRT (n = 104) or ConvRT (n = 96) arms.

Interventions

Patients were randomly assigned to either high-precision SCRT or ConvRT to a dose of 54 Gy in 30 fractions over 6 weeks.

Main Outcomes and Measures

Detailed neuropsychological and neuroendocrine assessments were performed at preradiotherapy baseline, at 6 months, and annually thereafter until 5 years on longitudinal follow-up. Change in these functional parameters was compared between the 2 arms as the primary end point and overall survival (OS) as the secondary end point.

Results

In total, 200 young patients (median [interquartile range] age, 13 [9-17] years; 133 males and 67 females) were enrolled. Mean full-scale or global intelligence quotient (IQ) and performance IQ scores over a period of 5 years were significantly superior in patients treated with SCRT compared with those treated with ConvRT (difference in slope = 1.48; P = .04 vs difference in slope = 1.64; P = .046, respectively). Cumulative incidence of developing new neuroendocrine dysfunction at 5 years was significantly lower in patients treated with SCRT compared with ConvRT (31% vs 51%; P = .01) while developing a new neuroendocrine axis dysfunction in patients with preexisting dysfunction in at least 1 axis at baseline was also significantly lower in the SCRT arm compared with the ConvRT arm (29% vs 52%; P = .02). Five-year OS in SCRT and ConvRT arms was 86% and 91%, respectively (P = .54).

Conclusions and Relevance

In young patients with residual and/or progressive benign or low-grade brain tumors requiring radiotherapy for long-term tumor control, SCRT compared with ConvRT achieves superior neurocognitive and neuroendocrine functional outcomes over 5 years without compromising survival.

Trial Registration

clinicaltrials.gov Identifier: NCT00517959.

High prevalence of early hypothalamic-pituitary damage in childhood brain tumor survivors: need for standardized follow-up programs

INTRODUCTION

Childhood brain tumor survivors (CBTS) are at increased risk to develop endocrine disorders. Alerted by two cases who experienced delay in diagnosis of endocrine deficiencies within the first 5 years after brain tumor diagnosis, our aim was to investigate the current screening strategy and the prevalence of endocrine disorders in survivors of a childhood brain tumor outside of the hypothalamic-pituitary region, within the first 5 years after diagnosis.

PROCEDURES

Firstly, we performed a retrospective study of 47 CBTS treated in our center, diagnosed between 2008 and 2012. Secondly, the literature was reviewed for the prevalence of endocrine disorders in CBTS within the first 5 years after diagnosis.

RESULTS

Of 47 CBTS eligible for evaluation, in 34% no endocrine parameters had been documented at all during follow up. In the other 66%, endocrine parameters had been inconsistently checked, with different parameters at different time intervals. In 19% of patients an endocrine disorder was found. At literature review 22 studies were identified. The most common reported endocrine disorder within the first 5 years after diagnosis was growth hormone deficiency (13-100%), followed by primary gonadal dysfunction (0-91%) central hypothyroidism (0-67%) and primary/subclinical hypothyroidism (range 0-64%).

CONCLUSION

Endocrine disorders are frequently seen within the first 5 years after diagnosis of a childhood brain tumor outside of the hypothalamic-pituitary region. Inconsistent endocrine follow up leads to unnecessary delay in diagnosis and treatment. Endocrine care for this specific population should be improved and standardized. Therefore, high-quality studies and evidence based guidelines are warranted.

Obesity and craniopharyngioma

An epidemic of pediatric obesity has occurred across the world in recent years. There are subgroups within the population at high-risk of becoming obese and especially of having experience of precocious cardiovascular and metabolic co-morbidities of obesity. One of these subgroups comprises patients treated for childhood cancers and namely survivors of craniopharyngioma. The high incidence of obesity in this group makes these patients an important disease model to better understand the metabolic disturbances and the mechanisms of weight gain among cancer survivors. The hypothalamic-pituitary axis damage secondary to cancer therapies or to primary tumor location affect long-term outcomes. Nevertheless, the aetiology of obesity in craniopharyngioma is not yet fully understood. The present review has the aim of summarizing the published data and examining the most accepted mechanisms and main predisposing factors related to weight gain in this particular population.

Time course of hypothalamic-pituitary deficiency in adults receiving cranial radiotherapy for primary extrasellar brain tumors

BACKGROUND

No longitudinal data on hypothalamic-pituitary (HP) function are available in patients who had received cranial radiation therapy (CRT) for primary extrasellar brain tumors (PBT).

PURPOSE

To investigate the effects of CRT on HP function in adults with PBT.

PATIENTS AND METHODS

Twenty-six adults irradiated for PBT and six CRT naive controls were studied. CRT was delivered with 6 MV X-ray by a linear accelerator (2 Gy fraction schedule). Gross Tumor Volume (GTV) excluded the HP region that was contoured on the planning CT. Median dose to the HP region was 41.8 Gy (IQR: 30.7-49.8).

RESULTS

All controls maintained normal HP function. Hypopituitarism developed in 38% of CRT patients (GH deficiency 29%, ACTH 22%, TSH 14%, gonadotropin 4%, no abnormal prolactin level or diabetes insipidus). All HP failures occurred within 32 months after CRT.

CONCLUSIONS

Adults undergoing CRT for PBT are at increased risk for HP dysfunction within 3 years from CRT. Endocrine surveillance is recommended also in adults patients exposed to CRT for primary brain tumors distant from HP region.

Stereotactic radiotherapy and radiosurgery in pediatric patients: analysis of indications and outcome

INTRODUCTION

We describe indications, outcomes, and risk profiles of fractionated stereotactic radiotherapy (SRT) and single fraction "radiosurgery" (SRS) in pediatric patients compared to the adult population and evaluate the causal role of SRS and SRT in inducing new neurological complications.

MATERIALS AND METHODS

Six children with AVMs and 12 children with neoplastic diseases were prospectively followed for >2 years after SRT/S. The survival, control of pathology, and specified neurological complications were analyzed. In tumor patients, the median overall survival time was 45 months (range 5-103) and the median progression free survival time was 35 months (range 5-98).

RESULTS

Control or regression of the tumor was obtained in 83% of patients with neoplastic disease. Three patients with malignant tumors died from disease progression. In AVMs the median time follow up was 52 months (range 27-100). All AVMs were obliterated. New neurological deficits occurred in 67%. SRT/S was considered the direct cause in 25%. All the neurological deficiencies related to SRT/S were focal and related to the irradiated areas. In tumor patients, midline lesions, malignant diagnosis, and additional treatment with surgery, chemotherapy, and craniospinal irradiation seemed to increase the risk of new deficits after SRT/S. In AVM patients, a high Spetzler-Martin grade seemed to carry a higher complication risk.

CONCLUSION

The risk of uncontrolled tumor disease or the risk of hemorrhage of non-obliterated AVM must be balanced against the overall risks and benefits of SRT/S. Following SRT/S, the risk of worsening pre-existing deficits is relatively high. The risk of inducing new long-term deficits is relatively low.

Outcomes of pediatric patients with malignancies of the major salivary glands

BACKGROUND

To report the outcomes and early to long term treatment complications among pediatric patients with major salivary gland malignancies treated at a single institution.

MATERIALS AND METHOD

This study was a retrospective case review set at a tertiary referral cancer center. Patients less than 19 years of age with a diagnosis of a major salivary gland malignancy were identified at the M. D. Anderson tumor database between 1953 and 2006.

RESULTS

A total of 61 patients were identified, with equal gender distribution. The majority of tumors arose in the parotid gland (83%), and the most common pathology was mucoepidermoid carcinoma (46%). Lymphatic metastasis was identified in 37% of patients, nearly all with mucoepidermoid carcinoma. Although 65% of patients had prior treatment elsewhere, more than 75% of patients underwent surgical resection at our institution. External beam radiation was used in 45% of patients, with an average dose of 58.6 Gray. Average patient follow-up was 153 months. The overall survival rate was 93% at 5 years, and 26% developed a recurrence. A second primary was identified in 2 patients. Permanent facial paresis was noted in 7 patients (12%) and xerostomia in 1 patient (4%).

CONCLUSIONS

Survival of pediatric patients with major salivary gland carcinomas is favorable. Adverse outcomes were best predicted by tumor grade, margin status, and neural involvement. Radiation therapy is beneficial for locoregional control of disease, with acceptable long-term treatment sequelae, and without a significant risk for developing second primary tumors. Survivorship issues need to be addressed in this patient population into adulthood.

Intensity-modulated radiotherapy plan optimisation for skull base lesions: practical class solutions for dose escalation

AIMS

To identify practical intensity-modulated radiotherapy planning solutions when attempting dose escalation in the skull base.

MATERIALS AND METHODS

Twenty cases of skull base meningioma were re-planned using a variation of beam number (three, five, seven and nine), beam arrangement (coplanar vs non-coplanar) and multileaf collimator (MLC) width (2.5 mm vs 10 mm) to 60 Gy/30 fractions. Plan quality and planning target volume coverage was assessed using planning target volume V(95%), equivalent uniform dose (EUD) and integral dose.

RESULTS

Critical structures were maintained below clinical tolerance levels. The 2.5 mm MLC achieved an average improvement in V(95%) by 22.8% (P=0.0003), EUD by 3.7 Gy (P=0.002) and reduced the integral dose by 13.4 Gy (P=0.0001). V(95%) and the integral dose improved with five vs three beams and seven vs five beams, but did not change with nine vs seven beams. There was no effect of beam number on EUD. There was no difference in V(95%) (P=0.54), integral dose (P=0.44) or EUD (P=0.47) for beam arrangement used. Segments per plan increased by a factor of 1.5 with each addition of two beams to a plan, and by a factor of 2.5 for 2.5 mm MLC plans vs 10 mm MLC plans.

CONCLUSIONS

We present evidence-based planning solutions for skull base intensity-modulated radiotherapy, and show that 2.5 mm MLC and five to seven beams can achieve safe dose escalation up to 60 Gy. This must be balanced with an increase in segmentation, which will increase treatment times.

Endocrine outcomes for children with embryonal brain tumors after risk-adapted craniospinal and conformal primary-site irradiation and high-dose chemotherapy with stem-cell rescue on the SJMB-96 trial

PURPOSE

To estimate the cumulative incidence of specific hormone deficiencies and the influence of hypothalamic-pituitary (HP) axis radiation dose in a cohort of children with embryonal brain tumors treated with risk-adapted craniospinal irradiation (CSI), conformal primary site irradiation, and high-dose chemotherapy.

PATIENTS AND METHODS

Clinical data and HP axis radiation dosimetry data were obtained from 88 eligible children. All patients received regular endocrine follow-up that included screening tests of thyroid function and stimulation testing for growth hormone deficiency (GHD), and adrenocorticotropin hormone deficiency.

RESULTS

The cumulative incidence of GHD, thyroid-stimulating hormone (TSH) deficiency, adrenocorticotropic hormone deficiency, and primary hypothyroidism at 4 years from diagnosis was 93% +/- 4%, 23% +/- 8%, 38% +/- 6%, and 65% +/- 7%, respectively. Radiation dosimetry to the HP axis was associated only with the development of TSH deficiency; the 4-year cumulative incidence was 44% +/- 19% and 11% +/- 8% (P = .014) for those receiving more or less than the median dose to the hypothalamus (>or= 42 v < 42 Gy), respectively. The median dose of CSI for the average-risk (AR) patients was 23.4 and 39.6 Gy (36 to 40.5 Gy) for the high-risk patients. The estimated mean decline in height Z-score after radiation therapy was greater in high-risk patients (-0.65 units/yr) when compared with AR patients (-0.54 units/yr; P = .039).

CONCLUSION

Pediatric patients with CNS embryonal tumors are at high risk for treatment-related hormone deficiencies. GHD and primary hypothyroidism were diagnosed in a majority of subjects relatively soon after the completion of therapy. Radiation dose to the hypothalamus in excess of 42 Gy was associated with an increase in the risk of developing TSH deficiency.

Nuclear Medicine in Pediatric Neurology and Neurosurgery: Epilepsy and Brain Tumors

In pediatric drug-resistant epilepsy, nuclear medicine can provide important additional information in the presurgical localization of the epileptogenic focus. The main modalities used are interictal (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) and ictal regional cerebral perfusion study with single-photon emission computed tomography (SPECT). Nuclear medicine techniques have a sensitivity of approximately 85% to 90% in the localization of an epileptogenic focus in temporal lobe epilepsy; however, in this clinical setting, they are not always clinically indicated because other techniques (eg, icterictal and ictal electroencephalogram, video telemetry, magnetic resonance imaging [MRI]) may be successful in the identification of the epileptogenic focus. Nuclear medicine is very useful when MRI is negative and/or when electroencephalogram and MRI are discordant. A good technique to identify the epileptogenic focus is especially needed in the setting of extra-temporal lobe epilepsy; however, in this context, identification of the epileptogenic focus is more difficult for all techniques and the sensitivity of the isotope techniques is only 50% to 60%. This review article discusses the clinical value of the different techniques in the clinical context; it also gives practical suggestions on how to acquire good ictal SPECT and interictal FDG-PET scans. Nuclear medicine in pediatric brain tumors can help in differentiating tumor recurrence from post-treatment sequelae, in assessing the response to treatment, in directing biopsy, and in planning therapy. Both PET and SPECT tracers can be used. In this review, we discuss the use of the different tracers available in this still very new, but promising, application of radioisotope techniques.

High precision conformal radiotherapy employing conservative margins in childhood benign and low-grade brain tumours

BACKGROUND AND PURPOSE

To report local control and follow up outcome data of high precision conformal radiotherapy in childhood brain tumours.

MATERIALS AND METHODS

Between December 1999 and December 2002, 26 children (17 boys and 9 girls, median age 11.5 years) with incompletely excised or recurrent benign and low-grade brain tumours [13 craniopharyngiomas, 11 low-grade gliomas (LGG) and 2 others] were treated with three-dimensional (3D) conformal radiotherapy (CRT) (12 patients) and stereotactic conformal radiotherapy (SCRT) (14 patients). Gross tumour volume (GTV) included neuro-imaging based visible tumour and/or resected tumour bed. Clinical target volume (CTV) consisted of GTV+ 5 mm margin and planning target volume (PTV) consisted of additional 5 mm margin for CRT and 2 mm for SCRT. Treatment was delivered with 3-9 conformal fixed fields to a median dose of 54 Gy/30 fractions.

RESULTS

The actuarial 2 and 3 year disease free and overall survival was 96 and 100%, respectively (median follow up: 25 months, range 12-47 months). Radiological follow up available in 25 patients revealed complete response in 1, partial regression in 10, stable disease in 13 and progression in 1 patient (within the CTV). One patient with craniopharyngioma on a routine imaging revealed a mild asymptomatic cyst enlargement, which resolved with conservative management. A patient with chiasmatic glioma developed cystic degeneration and hydrocephalus 9 months after SCRT requiring cyst drainage and placement of a ventriculoperitoneal shunt.

CONCLUSION

High-precision conformal techniques delivering irradiation to a computer generated target volume employing 7-10 mm 3D margins beyond the visible tumour and/or resected tumour bed appear to be safe in children with incompletely resected or recurrent benign and low-grade brain tumours, based on these data.

Final height and body mass index among adult survivors of childhood brain cancer: childhood cancer survivor study

The objectives of this study were 1) to compare final height and body mass index (BMI) between adult survivors of childhood brain cancer and age- and sex-matched population norms, 2) to quantify the effects of treatment- and cancer-related factors on the risk of final height below the 10th percentile (adult short stature) or having a BMI of 30 kg/m(2) or more (obesity). Treatment records were abstracted and surveys completed by 921 adults aged 20-45 yr who were treated for brain cancer as children and were participants in the multicenter Childhood Cancer Survivor Study. Nearly 40% of childhood brain cancer survivors were below the 10th percentile for height. The strongest risk factors for adult short stature were young age at diagnosis and radiation treatment involving the hypothalamic-pituitary axis (HPA). The multivariate odds ratio for adult short stature among those 4 yr of age or younger at diagnosis, relative to ages 10-20 yr, was 5.67 (95% confidence interval, 3.6-8.9). HPA radiation exposure increased the risk of adult short stature in a dose-response fashion (trend test, P < 0.0001). Adjuvant chemotherapy was not an independent risk factor for adult short stature. BMI distribution in survivors did not differ appreciably from that of population norms; however, in females, young age at diagnosis and HPA radiation dose (trend test, P < 0.001) were associated with risk of obesity. Except for patients treated with surgery only, survivors of childhood brain cancer are at very high risk for adult short stature, and this risk increases with radiation dose involving the HPA. We did not find a corresponding elevated risk for obesity.

GH deficiency caused by cranial irradiation during childhood: factors and markers in young adults

Cranial irradiation alters hypothalamic-pituitary function. We reevaluated 90 patients with GH deficiency caused by fractionated cranial irradiation performed at age 4.9 +/- 0.4 (SE) yr when they were 15.7 +/- 0.2 yr old. Group 1 received 18 Grays (Gy) (7 cases) or 24 Gy (21 cases) for acute lymphoblastic leukemia; group 2, 30-40 Gy for medulloblastoma (22 cases); group 3, 45-60 Gy for optic glioma and various tumors (30 cases); and group 4, 40-50 Gy for retinoblastoma (10 cases). The mean GH peaks after an arginine insulin test in group 3 (1.9 +/- 0.4 microg/liter) was lower than in groups 1 (4.8 +/- 0.5 microg/liter, P < 0.001) and 2 (3.4 +/- 0.5 microg/liter, P < 0.03). The mean plasma IGF-I concentrations in group 3 [-3.8 +/- 0.2 z score (zs)] was lower than in groups 1 (-2.4 +/- 0.3 zs, P < 0.001) and 2 (-3.1 +/- 0.2 zs, P < 0.02), as was the mean in group 4 (-3.9 +/- 0.3 zs, P < 0.01 compared with group 1 and P < 0.05 compared with group 2). GH peaks and IGF-I were correlated positively (P = 0.0001) and negatively with dose (P < 0.001 for GH and P = 0.0001 for IGF-I), but not with age at irradiation. Among the 43 patients with GH peaks below 3 microg/liter, 41 (95%) had plasma IGF-I less than -2 zs. The body mass index (BMI), plasma insulin, and leptin were similar in the four groups. They were positively correlated with each other (P < 0.001 for BMI compared with insulin and with leptin, respectively, and P < 0.01 for insulin compared with leptin), but not with age or dose of irradiation, or with markers of GH secretion. In conclusion, in patients with GH deficiency caused by cranial irradiation, the residual GH secretion and plasma IGF-I depend on the dose. Almost all the patients with severe GH deficiency had low plasma IGF-I. BMI, leptin, and insulin seem to be independent of GH status.

Cranial irradiation and central hypothyroidism

Cranial irradiation causes thyrotropin (TSH)-releasing hormone (TRH) secretory abnormalities. TRH deficiency leads to abnormal glycosylation of TSH alpha and beta subunits and loss of the normal circadian pattern of TSH secretion (low in the afternoon, a surge in the evening, higher at night). This disruption results in either mixed hypothyroidism (raised TSH with abnormal secretory kinetics) or central hypothyroidism (abnormal secretory kinetics without raised TSH). Although primary hypothyroidism is more common in the general population and cancer survivors, the cumulative incidence of central and mixed hypothyroidism is high during the ten years after cranial irradiation. Monitoring for decline in free thyroxine (FT(4)) and rise in serum TSH, and early recognition using TSH surge and TRH tests, are clinically valuable. Early thyroid hormone replacement therapy to achieve serum FT(4) in the upper half of the normal range is crucial for maintaining optimal health and growth in cancer survivors.

Adult height and age at menarche in childhood cancer survivors

The aim of this study was to assess the long-term effects of cancer treatments on adult height and age at menarche in survivors of various types of childhood cancer. 285 childhood cancer survivors (161 men and 124 women), at least 18 years old and having been off treatment for at least 5 years, were examined. The effects of cranial (CrRT) and craniospinal irradiation (CrSpRT), other treatments and age at diagnosis on adult height and age at menarche were investigated. Patients who did not receive CrRT or CrSpRT, reached normal adult heights. However, a significant reduction in adult height was observed in men and women treated with CrRT or CrSpRT, especially if the treatment was given at the age of 8 years or younger. In girls, CrRT resulted in a significantly earlier menarche, compared with the Dutch population. Chemotherapy, radiation dose and age at menarche did not affect adult height. The relative risk (RR) of attaining an adult height below the 3rd percentile (20% 49/244) of the study population) was 6 times increased (RR=6.4; 95% confidence interval (CI) 1.46-28.52) after CrSpRT, 4 times (RR=4.2; 95% CI 1.81-9.63) after Crth and 5 times (RR=51; 95% CI 2.23-11.59) when irradiation was administered at the age of 8 years or younger. CrRT and CrSpRT and age at treatment are the main determinants of short stature in male and female childhood cancer survivors.

Cranial radiotherapy of childhood brain tumours: growth hormone deficiency and its relation to the biological effective dose of irradiation in a large population based study

OBJECTIVE

The study was to determine the incidence of GH deficiency (GHD) following cranial radiotherapy (RT) for a childhood brain tumour in a large population based study and analyse the biological effective dose (BED) to the hypothalamus/pituitary (HP) region as a risk factor.

DESIGN

BED was assessed by use of the linear-quadratic (LQ) model, which gives a means of expressing the biological effect of various treatment schedules in a uniform way. In patients aged >/= 18 years (n = 53) GH status was assessed by an insulin-tolerance test (ITT) (n = 34), however, in patients with seizure disorders (n = 19), and in 20 children aged < 18 years GH status was assessed by an arginine test. Cut-off levels for GHD, indicating GH substitution, were defined by a peak GH response of < 9 mU/l and < 15 mU/l for patients >/= 18 and < 18 years, respectively.

PATIENTS

Ninety-one children aged < 15 years eligible for the study, diagnosed between 1970 and 1997 in the Eastern part of Denmark, the Faroe Islands and Greenland, with a primary brain tumour not directly involving the HP axis. 84% (n = 76) agreed to participate. Three patients were excluded due to hypothyroidism detected at time of testing.

MEASUREMENTS

Serum GH and levels of serum insulin-like growth factor-I (s-IGF-I) and serum insulin-like growth factor binding protein-3 (s-IGFBP-3) were measured. BED was assessed to the HP region.

RESULTS

The median age at the time of RT was 8.7 years (range: 0.8-14.9 years) and the median time of follow-up was 15 years (range: 2-28 years). Fifty-eight patients (80%) had GHD and they had received a median BED of 77.5 Gy to the HP region, whereas the median BED was 54.5 Gy for 15 patients without GHD (P = 0.002). Peak GH and BED were correlated (rs = -0.53, P < 0001). Median IGF-I SDS and IGFBP-3 SDS were -2.5 (-5.2-0.7 SDS) and -1.7 (-5.8-0.9 SDS), respectively, and IGF-I SDS was correlated to peak GH (rs = 0.45, P < 0.001). Peak GH and length of follow-up were related (rs = -0.28, P = 0.018). Stepwise backward multiple linear regression analysis showed that the best-fit model to predict the peak GH release following ITT/arginine stimulation included BED (P < 0.0001) and length of follow-up (P = 0.05).

CONCLUSIONS

The data of this study suggest that the majority of long-term survivors of brain tumours develop GH deficiency following radiotherapy in childhood and that the adverse effects of radiotherapy may be directly related to the biologically effective dose. With longer follow-up fewer patients might respond normally to GH stimulation tests.