Predictive factors for radiation-induced pituitary damage in pediatric patients with brain tumors.

BACKGROUND AND PURPOSE: Multiple studies demonstrated hypothalamic-pituitary dysfunction in survivors of pediatric brain tumors. However, few studies investigated the trajectories of pituitary height in these patients and their associations with pituitary function. We aimed to evaluate longitudinal changes of pituitary height in children and adolescents with brain tumors, and their association with endocrine deficiencies. MATERIALS AND METHODS: We conducted a retrospective analysis of 193 pediatric patients (54.9% male) diagnosed with brain tumors from 2002 to 2018, with a minimum of two years of radiological follow-up. Pituitary height was measured using MRI scans at diagnosis and at 2, 5, and 10 years post-diagnosis, with clinical data sourced from patient charts. RESULTS: Average age at diagnosis was 7.6 ± 4.5 years, with a follow-up of 6.1 ± 3.4 years. 52.8% underwent radiotherapy and 37.8% experienced pituitary hormone deficiency. Radiation treatment was a significant predictor of decreased pituitary height at all observed time points (p = 0.016, p < 0.001, p = 0.008, respectively). Additionally, chemotherapy (p = 0.004) or radiotherapy (p = 0.022) history and pituitary height at 10 years (p = 0.047) were predictors of endocrine deficiencies. ANOVA revealed an expected increase in pituitary height over time in pediatric patients, but this growth was significantly impacted by radiation treatment and gender (p for interaction = 0.005 and 0.025, respectively). CONCLUSION: Cranial irradiation in pediatric patients is associated with impairment of the physiologic increase in pituitary size; in turn, decreased pituitary height is associated with endocrine dysfunction. We suggest that pituitary gland should be evaluated on surveillance imaging of pediatric brain tumor survivors, and if small for age, clinical endocrine evaluation should be pursued.

Correlating measured radiotherapy dose with patterns of endocrinopathy: The importance of minimizing pituitary dose.

BACKGROUND: Pituitary insufficiency is a common toxicity of cranial radiotherapy received in childhood for central nervous system, head and neck, and hematological malignancies. There is a recognized deficiency pattern and correlation with prescribed radiotherapy dose; however, correlation with measured pituitary dose (which can be minimized with modern radiotherapy techniques) has not previously been assessed. PROCEDURE: Retrospective analysis was carried out of measured pituitary dose and endocrine outcomes of patients receiving cranial, total body, or head and neck photon beam radiotherapy at a tertiary center from July 2008 to October 2019. RESULTS: Complete data for 102 patients were available. Median (IQR) age at radiotherapy was 9.0 (6.0-12.0) and follow-up 5.7 years (3.5-9.1). Most patients received focal brain radiotherapy (36.3%) or total body irradiation (32.4%); most frequent diagnoses were acute lymphoblastic leukemia (25.5%) and medulloblastoma (17.6%). The majority developed pituitary insufficiency (64; 62.7%); 41% had one and 38% had two hormone deficiencies. Growth hormone deficiency (GHD) (58; 56.9%) and thyroid-stimulating hormone deficiency (TSHD) (32; 31.4%) were most common. Patients who developed pituitary insufficiency received higher maximum pituitary dose-median (IQR) Gy, 44.0 (20.4-54.0) vs 18.2 (14.4-52.6); P = 0.008. Doses of 40-49 Gy or >50 Gy led to a higher cumulative incident rate than <20 Gy (HR 4.07, P < 0.001 and HR 3.04, P < 0.001, respectively). However, even at lower dose bands, levels of pituitary insufficiency were significant with a five-year cumulative incidence of GHD for <20 Gy and TSHD for 20-29 Gy reaching >30%. CONCLUSIONS: Our findings confirm a correlation between measured pituitary dose and risk of insufficiency even at lower doses, despite modern radiotherapy techniques. These data highlight the importance of minimizing pituitary dose and early specialist endocrine follow-up.

High prevalence of anterior pituitary deficiencies after cranial radiation therapy for skull base meningiomas.

BACKGROUND: Cranial irradiation represents one of the first line treatment proposed in skull base meningiomas. While cranial irradiation is associated with a high risk of secondary hypopituitarism, few studies focused on the specific location of skull base meningiomas. METHODS: Fifty-two adults receiving photon-beam therapy for skull base meningiomas between 2003 and 2014 in our Institution were included. Anterior pituitary (ACTH, FSH, GH, LH, TSH and prolactin) as well as corresponding peripheral hormones (8 am-Cortisol, IGF-1, fT3, fT4, 17ßestradiol or testosterone) were biologically screened before radiotherapy (baseline), then yearly until March 2019. The pituitary gland (PG) was delineated on CT and the mean dose delivered to it was calculated. RESULTS: Mean age at diagnosis was 56 +/- 14 years. Median follow-up was 7 years. Up to 60% of patients developed at least ≥2 pituitary deficiencies, 10 years after radiotherapy. Gonadotroph, thyrotroph, corticotroph and somatotroph deficiencies occurred in 37, 28, 18 and 15% of patients, respectively. Hyperprolactinemia was found in 13% of patients. None patient had only one pituitary deficiency. In the multivariate analysis, a delivered dose to the PG ≥ 50 Gy or a meningioma size ≥40 mm significantly increased the risk of developing hypopituitarism. CONCLUSIONS: Over a long-term follow-up, cranial radiation therapy used in skull base meningiomas led to a high prevalence of hypopituitarism, further pronounced in case of tumor ≥4 cm. These results advocate for an annual and prolonged follow-up of the pituitary functions in patients with irradiated skull base meningiomas.

Pituitary Function after High-Dose 177Lu-DOTATATE Therapy and Long-Term Follow-Up.

INTRODUCTION: The pituitary gland has a high expression of somatostatin receptors and is therefore a potential organ at risk for radiation-induced toxicity after 177Lu-DOTATATE treatment. OBJECTIVE: To study changes in pituitary function in patients with neuroendocrine tumors (NETs) treated with dosimetry-based 177Lu-DOTATATE to detect possible late toxicity. METHODS: 68 patients from a phase II clinical trial of dosimetry-based, individualized 177Lu-DOTATATE therapy were included in this analysis. Patients had received a median of 5 (range 3-9) treatment cycles of 7.4 GBq/cycle. Median follow-up was 30 months (range 11-89). The GH/IGF-1 axis, gonadotropins, and adrenal and thyroid axes were analyzed at baseline and on a yearly basis thereafter. Percent changes in hormonal levels over time were analyzed statistically using a linear mixed model and described graphically using box plots. The absorbed radiation dose to the pituitary was estimated based on post-therapeutic imaging, and the results analyzed versus percent change in IGF-1 levels over time. RESULTS: A statistically significant decrease in IGF-1 levels was found (p < 0.005), which correlated with the number of treatment cycles (p = 0.008) and the absorbed radiation dose (p = 0.03). A similar decrease, although non-significant, was seen in gonadotropins in postmenopausal women, while in men there was an increase during the first years after therapy, after which the levels returned to baseline. No change was observed in the adrenal or thyroid axes. CONCLUSIONS: No signs of severe endocrine disorders were detected, although a significant decrease in the GH/IGF-1 axis was found, where dosimetric analyses indicated radiation-induced damage to the pituitary gland as a probable cause.

Cranial irradiation alters neuroinflammation and neural proliferation in the pituitary gland and induces late-onset hormone deficiency.

Cranial radiotherapy induces endocrine disorders and reproductive abnormalities, particularly in long-term female cancer survivors, and this might in part be caused by injury to the pituitary gland, but the underlying mechanisms are unknown. The aim of this study was to investigate the influence of cranial irradiation on the pituitary gland and related endocrine function. Female Wistar rat pups on postnatal day 11 were subjected to a single dose of 6 Gy whole-head irradiation, and hormone levels and organ structure in the reproductive system were examined at 20 weeks after irradiation. We found that brain irradiation reduced cell proliferation and induced persistent inflammation in the pituitary gland. The whole transcriptome analysis of the pituitary gland revealed that apoptosis and inflammation-related pathways were up-regulated after irradiation. In addition, irradiation led to significantly decreased levels of the pituitary hormones, growth hormone, adrenocorticotropic hormone, thyroid-stimulating hormone and the reproductive hormones testosterone and progesterone. To conclude, brain radiation induces reduction of pituitary and reproduction-related hormone secretion, this may due to reduced cell proliferation and increased pituitary inflammation after irradiation. Our results thus provide additional insight into the molecular mechanisms underlying complications after head irradiation and contribute to the discovery of preventive and therapeutic strategies related to brain injury following irradiation.

Hypothalamic-Pituitary Axis Dysfunction after Whole Brain Radiotherapy - A Cohort Study.

BACKGROUND/AIM: Hypothalamic-pituitary (HT-P) dysfunction is one of the most common endocrine late effects following cranial radiotherapy. However, there are currently no specific data describing this complication in adult-onset cancer patients after whole brain radiotherapy (WBRT). The present cohort study aims to establish the prevalence of HT-P axis dysfunction in this group of patients. PATIENTS AND METHODS: Twenty-six cancer patients previously treated with WBRT (median follow-up=20.5 months) received standardized endocrine check-up focusing on HT-P function. RESULTS: In 50% of the patients, impaired hypothalamic-pituitary function was detected during follow-up. While functional loss of a single hormonal axis was evident in 34.6% of patients, 7.7% showed an impairment of multiple endocrine axes, and one patient developed adrenocorticotropic hormone deficiency. Hypothalamic-pituitary dysfunction did not directly correlate with the applied WBRT total doses. CONCLUSION: In our cohort, hypothalamic-pituitary dysfunction appeared to be common after WBRT and was diagnosed as early as 6 months following radiation. This finding highlights the need for routine endocrine follow-up even in patients with limited life expectancy.

Sparing the hippocampus and the hypothalamic- pituitary region during whole brain radiotherapy: a volumetric modulated arc therapy planning study.

BACKGROUND: Feasibility testing of a simultaneous sparing approach of hippocampus, hypothalamus and pituitary gland in patients undergoing whole-brain radiotherapy (WBRT) with and without a concomitant boost to metastatic sites. INTRODUCTION: Cognitive impairment and hormonal dysfunction are common side effects of cranial radiotherapy. A reduced dose application to the patho-physiologically involved functional brain areas, i.e. hippocampus, hypothalamus and pituitary gland, could reduce these common side effects. While hippocampal sparing is already a common practice to improve cognitive outcome, technical experience of additional combined sparing of the hypothalamus/pituitary gland (HT-P) is insufficient. METHODS: Twenty patients were included in the planning study. In 11 patients, a total dose of 36 Gy of WBRT (2 Gy per fraction) plus a simultaneous integrated boost (SIB) of 9 Gy (0.5 Gy per fraction, total dose: 45 Gy) to the brain metastases was applied. In 9 patients, prophylactic cranial irradiation (PCI) was simulated with a total dose of 30 Gy (2 Gy per fraction). In both patient cohorts, a sparing approach of the hippocampus and the HT-P area was simulated during WBRT. For all treatment plans, volumetric modulated arc therapy (VMAT) was used. Quality assurance included assessment of homogeneity, conformality and target coverage. RESULTS: The mean dose to the hippocampus and HT-P region was limited to less than 50% of the prescribed dose to the planning target volume (PTV) in all treatment plans. Dose homogeneity (HI) of the target volume was satisfying (median HI = 0.16 for WBRT+SIB and 0.1 for PCI) and target coverage (conformation number, CN) was not compromised (median CN = 0.82 for SIB and 0.86 for PCI). CONCLUSION: Simultaneous dose reduction to the hippocampus and the HT-P area did not compromise the PTV coverage in patients undergoing WBRT+SIB or PCI using VMAT. While the feasibility of the presented approach is promising, prospective neurologic, endocrine outcome and safety studies are required.

Model-based calculation of thyroid gland normal tissue complication probability in head and neck cancer patients after radiation therapy.

AIM: Primary hypothyroidism is one of the late complications that can occur after radiation therapy for malignant tumors in the head and neck region. The aim of this retrospective study was to show the validity of the Lyman-Kutcher-Burman (LKB) normal tissue complication model for thyroid gland based on clinical results. METHODS: Thyroid function was evaluated by measuring thyroid-stimulating hormone and free thyroxine serum levels before radiation therapy, 3 months after the beginning of radiation therapy, and afterwards at each follow-up visit. Cumulative incidence was calculated using the Kaplan-Meier method. Dose-volume histogram, total dose, fractionation schedule, total duration of the treatment, and other parameters were used for normal tissue complication probability calculation based on the LKB model. The model was evaluated after fitting with the three sets of parameters for grade 2 hypothyroidism: 1) "Emami," where n = 0.22; m = 0.26, and D50 = 80 Gy; 2) "mean dose," where n = 1; m = 0.27, and D50 = 60 Gy; and 3) "Lyman EUD," where n = 0.49; m = 0.24, and D50 = 60 Gy. A value 3.0 Gy was used for α/ß ratio RESULTS: Eighty-three patients treated with volumetric modulated arc therapy for head and neck cancers at the University Hospital Martin, Slovakia, from January 2014 to July 2017, were included in the retrospective study. Median follow-up was 1.2 years. Cumulative incidence of hypothyroidism grade 2 or higher after 12 and 24 months was 9.6 and 22.0%, respectively. Normal tissue complication probability values calculated with mean dose and Lyman EUD parameters showed the best correlation with our clinical findings. CONCLUSION: Empirically based modelling of normal tissue complication probability was valid for our cohort of patients. With carefully chosen parameters, the LKB model can be used for predicting the normal tissue complication probability value.

[What is the impact of IMRT of nasopharyngeal carcinomas on glandular structures?] / Quel impact de la RCMI des carcinomes nasopharyngés sur les structures glandulaires ?

PURPOSE: The aim of this work is to evaluate the anatomical changes of the glandular structures during the NPC IMRT and to study their dosimetric impacts. PATIENTS AND METHODS: Twenty patients receiving IMRT for NPC were included. For each patient, a second dosimetric CT was performed at a dose of 38Gy, which was fused with the initial planning dosimetric CT. We calculated the volume percent change, the positional and dosimetric variation between the 2 scanners for the glandular structures (parotid, submaxillary, thyroid and pituitary). RESULTS: We observed a decrease in the volume of right and left parotids (-27.9% and -27.54%). It was correlated with the initial dose planned at its level. For the sub maxillary glands, the decrease was -36.1% on the right and -27.28% on the left. The value of reduction of the thyroid gland was -18.01%. A medial supra-millimeter migration of 2 and 1.15mm was found for right and left parotid glands respectively, correlated with GTV N reduction volume. We found a significant increase in mean doses for the parotid glands. It was 1.8±2.3Gy for the right and 1.5±2.7Gy for the left. For the right sub maxillary gland, the increase was about 0.35±2Gy and 3.79±5.2Gy for the thyroid. CONCLUSION: The modifications observed for glandular structures during NPC IMRT can explain the different toxicities caused by radiation. It seems also that a careful adaptation of the treatment plan should be considered during therapy.

The effects of chromatic lights on body color and gene expressions of melanin-concentrating hormone and proopiomelanocortin in goldfish (Carassius auratus).

In the present study, the effects of photic environments, such as background color (white and black) and chromatic lights (blue, green, and red), on body color and gene expressions of melanin-concentrating hormone (mch) in the brain and proopiomelanocortin (pomc) in the pituitary, as well as the roles of the eyes and brain as mediators of ambient light to these genes, were examined in goldfish (Carassius auratus). Body color of goldfish exposed to fluorescent light (FL) under white background (WBG) was paler than those under black background (BBG). Gene expression levels for mch and pomc were reciprocally different depending on background color; under WBG, mRNA levels of mch and pomc were high and low, respectively, while under BBG, these levels were reversed. mch and pomc mRNA expressions of the fish exposed to chromatic light from LED were primarily similar to those exposed to FL, while blue light stimulated the expressions of mch and pomc. Ophthalmectomized goldfish exposed to FL or blue light showed minimum expression levels of mch gene, suggesting that eyes are the major mediator of ambient light for mch gene expression. Contrastingly, mRNA expressions of pomc in ophthalmectomized goldfish exposed to FL were different from those of intact goldfish. These results suggest that eyes play a functional role in mediating ambient light to regulate pomc gene expression. Since ophthalmectomy caused an increase in pomc mRNA contents in the fish exposed to blue light, we suggest that the brain is an additional mediator to regulate pomc gene expression.

Are hypothalamic- pituitary (HP) axis deficiencies after whole brain radiotherapy (WBRT) of relevance for adult cancer patients? - a systematic review of the literature.

BACKGROUND: Cranial radiotherapy (cRT) can induce hormonal deficiencies as a consequence of significant doses to the hypothalamic-pituitary (HP) axis. In contrast to profound endocrinological follow-up data from survivors of childhood cancer treated with cRT, little knowledge exists for adult cancer patients. METHODS: A systematic search of the literature was conducted using the PubMed database and the Cochrane library offering the basis for our debate of the relevance of HP axis impairment after cRT in adult cancer patients. Against the background of potential relevance for patients receiving whole brain radiotherapy (WBRT), a particular focus was set on the temporal onset of hypopituitarism and the radiation dose to the HP axis. RESULTS: Twenty-eight original papers with a total of 1728 patients met the inclusion criteria. Radiation doses to the HP area ranged from 4 to 97 Gray (Gy). Hypopituitarism incidences ranged from 20 to 93% for adult patients with nasopharyngeal cancer or non-pituitary brain tumors. No study focused particularly on hypopituitarism after WBRT. The onset of hypopituitarism occurred as early as within the first year following cRT (range: 3 months to 25.6 years). However, since most studies started follow-up evaluation only several years after cRT, early onset of hypopituitarism might have gone unnoticed. CONCLUSION: Hypopituitarism occurs frequently after cRT in adult cancer patients. Despite the general conception that it develops only after several years, onset of endocrine sequelae can occur within the first year after cRT without a clear threshold. This finding is worth debating particularly in respect of treatment options for patients with brain metastases and favorable survival prognoses.

Radiotherapy as a tool for the treatment of Cushing's disease.

Treatment of Cushing's disease (CD) is one of the most challenging tasks in endocrinology. The first-line treatment, transsphenoidal pituitary surgery, is associated with a high failure rate and a high prevalence of recurrence. Re-operation is associated with an even higher rate of a failure and recurrence. There are three main second-line treatments for CD - pituitary radiation therapy (RT), bilateral adrenalectomy and chronic cortisol-lowering medical treatment. All these treatments have their limitations. While bilateral adrenalectomy provides permanent cure of the hypercortisolism in all patients, the unavoidable chronic adrenal insufficiency and the risk of development of Nelson syndrome are of concern. Chronic cortisol-lowering medical treatment is not efficient in all patients and side effects are often a limiting factor. RT is efficient for approximately two-thirds of all patients with CD. However, the high prevalence of pituitary insufficiency is of concern as well as potential optic nerve damage, development of cerebrovascular disease and secondary brain tumours. Thus, when it comes to decide appropriate treatment for patients with CD, who have either failed to achieve remission with pituitary surgery, or patients with recurrence, the pros and cons of all second-line treatment options must be considered.

Fatigue following radiation therapy in nasopharyngeal cancer survivors: A dosimetric analysis incorporating patient report and observer rating.

PURPOSE: To explore for fatigue-related regions and the radiotherapy (RT) dose-fatigue relationship in nasopharyngeal cancer (NPC) survivors. METHODS: Eighty disease-free NPC survivors completed the MD Anderson Symptom Inventory-Head and Neck module (MDASI-HN) after RT. Fatigue was evaluated by the MDASI-HN fatigue item (MDASI-HN-F) and Common Terminology Criteria for Adverse Events v3.0 (CTC-AE), between 6 and 36 months after RT to determine the presence of chronic fatigue. Skull base MRIs and planning CT/RT dose were retrievable for 56 patients. Dosimetric data were extracted for 10 MRI-defined potential fatigue at-risk structures (FARS): brainstem (BS), pituitary gland (PG), hypothalamus (HT), basal ganglia, internal capsule, pineal gland, sub-thalamic nuclei, thalamus, substantia nigra, and hippocampus (HC). Recursive partitioning analysis (RPA) was used to identify dose-volume effects associated with chronic fatigue. RESULTS: 56 pts formed the cohort. Thirty patients (54%) reported any fatigue per MDASI-HN-F. Thirty-three pts (59%) had any fatigue by CTC-AE. The maximum point doses (Dmax) for PG, BS, HC, and HT were numerically higher in patients with fatigue. Dmax and Dmean of the PG were significantly higher in patients with chronic fatigue, p ≤ 0.01. A dose-volume threshold of PG V52 Gy ≥16% (LogWorth 2.4, AUC 0.7) was identified on RPA, and potential sensitivity to the PG doses was observed in younger patients (<53 years-old). CONCLUSION: A dose-fatigue relationship was identified for the pituitary gland, both patient-reported and observer ratings. We recommend limiting the Dmax of PG to <54 Gy and V52 Gy to <16%, particularly in young NPC patients, during plan optimization when achievable.

Hypothalamic-pituitary axis irradiation dose thresholds for the development of hypopituitarism in adult-onset gliomas.

BACKGROUND: Childhood brain tumour survivors who receive cranial radiotherapy undergo regular surveillance for the development ofhypothalamic-pituitary (HP) axis dysfunction. Much less attention has been given to radiation-induced hypopituitarism in patients with malignant brain tumours of adult onset. DESIGN: Retrospective cohort study. PATIENTS/MEASUREMENTS: We assessed the effects of cranial radiotherapy (cXRT) on pituitary function in 58 adults (32 male) with gliomas distant to the HP axis. The XRT dose exposure at the HP axis was correlated with individual axis dysfunction to establish dose thresholds. RESULTS: Mean age at cXRT was 41.2 ± 10.9 years and duration of endocrine follow-up 8.2 ± 5.2 years. Mean XRT dose to the HP axis was 35.9 ± 15.5 Gy. Overall prevalence of radiation-induced hypopituitarism was 84.5%. GH, LH/FSH, ACTH and TSH deficiency were present in 82.8%, 20.7%, 19% and 6.9% of patients, respectively. Hyperprolactinaemia was noted in 10.3% (n = 6) and was persistent in one case. GH deficiency and "any degree of hypopituitarism" positively correlated with the radiotherapy dose to the hypothalamic-pituitary axis. HP axis XRT dose thresholds for the development of GHD, LH/FSH, ACTH and TSH deficiency were established at 10, 30, 32 and 40.8 Gy, respectively. A gradual increase in the prevalence of all anterior pituitary hormone deficits was observed throughout the follow-up period. CONCLUSIONS: Hypopituitarism post-cXRT in adults with gliomas is a frequent, progressive and dose-dependent phenomenon. Dose thresholds suggest long-term endocrine surveillance is important where the HP axis XRT dose is higher than 30 Gy. Identification of deficits to allow early and appropriate hormone replacement therapy is important to improve well-being in these individuals with limited prognosis.

Hypopituitarism After Cranial Irradiation for Meningiomas: A Single-Institution Experience.

PURPOSE: Patients undergoing cranial irradiation are at high risk for development of subsequent pituitary deficiencies. Patients with meningiomas can expect to live many years after treatment and are therefore particularly vulnerable to long-term sequalae of radiation therapy (RT). The purpose of this study was to determine the rates and timing of onset of pituitary dysfunction across each hypothalamic-pituitary axis in patients with meningiomas in the sellar region. METHODS AND MATERIALS: Data from 74 patients with meningiomas in the sellar or perisellar region who underwent RT between 2001 and 2017 at a single academic center were analyzed. Dose-volume histograms were generated to determine the dose of radiation to the pituitary gland. Pituitary function tests were evaluated before and after completion of RT. RESULTS: There was a 20% risk for new hypopituitarism across any hypothalamic-pituitary axis after RT at a median follow-up of 43 months. Identified rates of dysfunction across each axis were 24% for thyroid and adrenal, 19% for growth hormone, and 10% for gonadal. Median time to develop deficiencies ranged from 11 months for growth hormone deficiency to 32 months for adrenal insufficiency. Deficiencies were likely to be correlated, with increased risk for thyroid dysfunction in patients with adrenal, gonadal, or prolactin deficiencies (P < .05). On univariate analysis, mean dose to the pituitary gland and male sex were associated with increased risk for post-RT thyroid deficiency (P = .01 and P = .004, respectively). There was no difference in rates of hypothyroidism after protons compared with photons (P = .14). CONCLUSIONS: Cranial irradiation for sellar meningiomas carries a risk for subsequent hypopituitarism that appears to be dose dependent and may occur years after completion of RT. Growth hormone deficiency and gonadal dysfunction were likely underestimated here secondary to a lack of routine testing. Given the favorable tumor prognosis in this patient population, early and long-term endocrine follow-up is warranted.

Hyperthyroidism After Radiation Therapy for Childhood Cancer: A Report from the Childhood Cancer Survivor Study.

PURPOSE: The association of hyperthyroidism with exposure to ionizing radiation is poorly understood. This study addresses the risk of hyperthyroidism in relation to incidental therapeutic radiation dose to the thyroid and pituitary glands in a large cohort of survivors of childhood cancer. METHODS AND MATERIALS: Using the Childhood Cancer Survivor Study's cohort of 5-year survivors of childhood cancer diagnosed at hospitals in the United States and Canada between 1970 and 1986, the occurrence of hyperthyroidism through 2009 was ascertained among 12,183 survivors who responded to serial questionnaires. Radiation doses to the thyroid and pituitary glands were estimated from radiation therapy records, and chemotherapy exposures were abstracted from medical records. Binary outcome regression was used to estimate prevalence odds ratios (ORs) for hyperthyroidism at 5 years from diagnosis of childhood cancer and Poisson regression to estimate incidence rate ratios (RRs) after the first 5 years. RESULTS: Survivors reported 179 cases of hyperthyroidism, of which 148 were diagnosed 5 or more years after their cancer diagnosis. The cumulative proportion of survivors diagnosed with hyperthyroidism by 30 years after the cancer diagnosis was 2.5% (95% confidence interval [CI], 2.0%-2.9%) among those who received radiation therapy. A linear relation adequately described the thyroid radiation dose response for prevalence of self-reported hyperthyroidism 5 years after cancer diagnosis (excess OR/Gy, 0.24; 95% CI, 0.06-0.95) and incidence rate thereafter (excess RR/Gy, 0.06; 95% CI, 0.03-0.14) over the dose range of 0 to 63 Gy. Neither radiation dose to the pituitary gland nor chemotherapy was associated significantly with hyperthyroidism. Radiation-associated risk remained elevated >25 years after exposure. CONCLUSIONS: Risk of hyperthyroidism after radiation therapy during childhood is positively associated with external radiation dose to the thyroid gland, with radiation-related excess risk persisting for >25 years. Neither radiation dose to the pituitary gland nor chemotherapy exposures were associated with hyperthyroidism among childhood cancer survivors through early adulthood.

Effects of green light on the growth of spotted halibut, Verasper variegatus, and Japanese flounder, Paralichthys olivaceus, and on the endocrine system of spotted halibut at different water temperatures.

We have previously shown that the somatic growth of barfin flounder, Verasper moseri, was promoted by green light. The present study was undertaken to elucidate whether growth-promoting effect of green light can be observed in other flatfishes and to understand the roles of endocrine systems in green light-induced growth. Herein, we demonstrated facilitation of growth by green light in the spotted halibut, Verasper variegatus, and Japanese flounder, Paralichthys olivaceus. Blue and blue-green light showed potencies that were similar to that of green light, while the potencies of red and white light were equivalent to that of ambient light (control). We also examined the effects of green light on growth and endocrine systems of V. variegatus at various water temperatures. Growth of the fish was facilitated by green light at four different water temperatures examined; the fish were reared for 31 days at 12 and 21 °C, and 30 days at 15 and 18 °C. Increase in condition factor was observed at 15 and 18 °C. Among the genes encoding hypothalamic hormones, expression levels of melanin-concentrating hormone 1 (mch1) were enhanced by green light at the four water temperatures. Expression levels of other genes including mch2 increased at certain water temperatures. No difference was observed in the expression levels of pituitary hormone genes, including those of growth hormone and members of proopiomelanocortin family, and in plasma levels of members of the insulin family. The results suggest that green light may generally stimulate growth of flatfishes. Moreover, it is conceivable that MCH, production of which is stimulated by green light, is a key hormone; it augments food intake, which is intimately coupled with somatic growth.

Simulation of proton range monitoring in an anthropomorphic phantom using multi-slat collimators and time-of-flight detection of prompt-gamma quanta.

Prompt-gamma (PG) imaging has the potential for monitoring proton therapy in real time. Different approaches are investigated. We focus on developing multi-slat collimators to image PG quanta, aiming at optimizing collimator performance to detect deviations in treatment delivery. We investigated six different multi-slat configurations, which have either optimal (analytical) intrinsic spatial resolution at fixed efficiency, or otherwise; at different distances from the proton pencil-beam axis (15 cm-35 cm). We used Geant4 to simulate irradiations of the head (energy: 130 MeV) and pelvis (200 MeV) of an anthropomorphic phantom, with and without physiologic/morphologic or setup changes of clinical dosimetric relevance. The particles escaping the phantom were transported through each of these multi-slat configurations and the gamma counts profiles were recorded at the collimator exit. Median filtering was applied to the registered PG-profiles to mitigate the effects of septa shadowing and statistical fluctuations. Time-of-flight discrimination was used to enhance the signal-to-background ratio, which appeared crucial for 200 MeV irradiations. Visual detection of the artificially introduced changes was possible by comparing the PG to the depth-dose profiles. Moreover, 2 mm range shifts could be detected in the head irradiation case using a simple linear regression fit to the falloff of the PG-profile. The influence of changes in complex, patient-like dose distributions on the PG-profiles obtained with multi-slat collimation is first studied in this work, which further gives insight on collimator design optimization and highlights its potential and simplicity for detecting proton treatment deviations over a wide range of Bragg peak positions.

Endocrine Deficiency As a Function of Radiation Dose to the Hypothalamus and Pituitary in Pediatric and Young Adult Patients With Brain Tumors.

PURPOSE: There are sparse data defining the dose response of radiation therapy (RT) to the hypothalamus and pituitary in pediatric and young adult patients with brain tumors. We examined the correlation between RT dose to these structures and development of endocrine dysfunction in this population. MATERIALS AND METHODS: Dosimetric and clinical data were collected from children and young adults (< 26 years of age) with brain tumors treated with proton RT on three prospective studies (2003 to 2016). Deficiencies of growth hormone (GH), thyroid hormone, adrenocorticotropic hormone, and gonadotropins were determined clinically and serologically. Incidence of deficiency was estimated using the Kaplan-Meier method. Multivariate models were constructed accounting for radiation dose and age. RESULTS: Of 222 patients in the study, 189 were evaluable by actuarial analysis, with a median follow-up of 4.4 years (range, 0.1 to 13.3 years), with 31 patients (14%) excluded from actuarial analysis for having baseline hormone deficiency and two patients (0.9%) because of lack of follow-up. One hundred thirty patients (68.8%) with medulloblastoma were treated with craniospinal irradiation (CSI) and boost; most of the remaining patients (n = 56) received involved field RT, most commonly for ependymoma (13.8%; n = 26) and low-grade glioma (7.4%; n = 14). The 4-year actuarial rate of any hormone deficiency, growth hormone, thyroid hormone, adrenocorticotropic hormone, and gonadotropin deficiencies were 48.8%, 37.4%, 20.5%, 6.9%, and 4.1%, respectively. Age at start of RT, time interval since treatment, and median dose to the combined hypothalamus and pituitary were correlated with increased incidence of deficiency. CONCLUSION: Median hypothalamic and pituitary radiation dose, younger age, and longer follow-up time were associated with increased rates of endocrinopathy in children and young adults treated with radiotherapy for brain tumors.