Clinical Importance of Free Thyroxine Concentration Decline After Radiotherapy for Pediatric and Adolescent Brain Tumors

Thyroid Profile in the First Three Months after Starting Treatment in Children with Newly Diagnosed Cancer

BACKGROUND

Thyroid hormone anomalies during childhood might affect neurological development, school performance and quality of life, as well as daily energy, growth, body mass index and bone development. Thyroid dysfunction (hypo- or hyperthyroidism) may occur during childhood cancer treatment, although its prevalence is unknown. The thyroid profile may also change as a form of adaptation during illness, which is called euthyroid sick syndrome (ESS). In children with central hypothyroidism, a decline in FT4 of >20% has been shown to be clinically relevant. We aimed to quantify the percentage, severity and risk factors of a changing thyroid profile in the first three months of childhood cancer treatment.

METHODS

In 284 children with newly diagnosed cancer, a prospective evaluation of the thyroid profile was performed at diagnosis and three months after starting treatment.

RESULTS

Subclinical hypothyroidism was found in 8.2% and 2.9% of children and subclinical hyperthyroidism in 3.6% and in 0.7% of children at diagnosis and after three months, respectively. ESS was present in 1.5% of children after three months. In 28% of children, FT4 concentration decreased by ≥20%.

CONCLUSIONS

Children with cancer are at low risk of developing hypo- or hyperthyroidism in the first three months after starting treatment but may develop a significant decline in FT4 concentrations. Future studies are needed to investigate the clinical consequences thereof.

Hormone replacement in survivors of childhood cancer and brain tumors: safety and controversies

Childhood cancer survivors are at risk for developing endocrine disorders, including deficits in growth hormone, thyroid hormone and sex hormones. The influence these hormones have on cell growth and metabolism has raised concerns regarding the safety of their use as treatments in survivors of childhood cancer and brain tumors. This article offers a summary of current knowledge, controversies and areas for future research pertaining to this area.

Endocrinopathy After Treatment for Medulloblastoma: Results From the SJMB03 Trial of Risk-Adapted Radiation Therapy

PURPOSE

The objective of this study was to estimate the cumulative incidence of endocrinopathy in pediatric patients treated for medulloblastoma with surgery, risk-adapted photon craniospinal irradiation, and dose-intensive chemotherapy.

METHODS AND MATERIALS

Children and adolescents (n = 156) treated between 2003 and 2013 were evaluated for evidence of endocrinopathy. Clinical information and mean radiation dose to hypothalamus and thyroid were calculated and used to estimate cumulative incidence of growth hormone deficiency, hypothyroidism, adrenal insufficiency, hypogonadism, and precocious puberty.

RESULTS

The 5-year cumulative incidences were estimated for growth hormone deficiency, 68.9% (60.9%, 75.6%); hypothyroidism, 48.4% (95% confidence interval (CI), 40.2%-56.1%); adrenal insufficiency, 13.0% (95% CI, 8.3%-18.9%); hypogonadism, 33.9% (95% CI, 25.2%-42.7%); and precocious puberty, 2.0% (95% CI, 0.6%-5.4%). Growth hormone deficiency was associated with increased hypothalamus dose (hazard ratio [HR], 1.035; 95% CI, 1.010-1.061; P = .0055) in average-risk patients and cerebrospinal fluid shunt (HR, 2.532; 95% CI, 1.325-4.838; P = .0049) in high-risk patients. In average-risk patients, hypothyroidism was associated with younger age (HR, 0.902; 95% CI, 0.842-0.973; P = .0070), hypothalamus dose (HR, 1.039; 95% CI, 1.004-1.075; P = .0273), and thyroid dose (HR, 1.070; 95% CI, 1.008-1.136; P = .0263). In high-risk patients, hypothyroidism was associated with increased hypothalamus dose (HR, 1.068; 95% CI, 0.995-1.147; P = .0671) and thyroid dose (HR, 1.050; 95% CI, 1.000-1.104; P = .0515). Adrenal insufficiency was associated with increased hypothalamus dose (HR, 1.112; 95% CI, 1.058-1.170; P < .0001). Growth hormone deficiency incidence was higher when comparing patients treated with cerebrospinal fluid shunt versus those not having a shunt/extraventricular drain placed during initial surgery (HR, 1.712; 95% CI, 1.109-2.643).

CONCLUSIONS

Incidence and time to onset of clinically significant endocrinopathy after photon craniospinal irradiation for pediatric medulloblastoma is influenced by radiation dose to target organs and patient age at time of treatment. Advanced radiation therapy methods and dose-reduction strategies are needed to reduce the incidence of endocrinopathy.

Hypothalamic-Pituitary and Other Endocrine Surveillance Among Childhood Cancer Survivors

Endocrine disorders in survivors of childhood, adolescent, and young adult (CAYA) cancers are associated with substantial adverse physical and psychosocial effects. To improve appropriate and timely endocrine screening and referral to a specialist, the International Late Effects of Childhood Cancer Guideline Harmonization Group (IGHG) aims to develop evidence and expert consensus-based guidelines for healthcare providers that harmonize recommendations for surveillance of endocrine disorders in CAYA cancer survivors. Existing IGHG surveillance recommendations for premature ovarian insufficiency, gonadotoxicity in males, fertility preservation, and thyroid cancer are summarized. For hypothalamic-pituitary (HP) dysfunction, new surveillance recommendations were formulated by a guideline panel consisting of 42 interdisciplinary international experts. A systematic literature search was performed in MEDLINE (through PubMed) for clinically relevant questions concerning HP dysfunction. Literature was screened for eligibility. Recommendations were formulated by drawing conclusions from quality assessment of all evidence, considering the potential benefits of early detection and appropriate management. Healthcare providers should be aware that CAYA cancer survivors have an increased risk for endocrine disorders, including HP dysfunction. Regular surveillance with clinical history, anthropomorphic measures, physical examination, and laboratory measurements is recommended in at-risk survivors. When endocrine disorders are suspected, healthcare providers should proceed with timely referrals to specialized services. These international evidence-based recommendations for surveillance of endocrine disorders in CAYA cancer survivors inform healthcare providers and highlight the need for long-term endocrine follow-up care in subgroups of survivors and elucidate opportunities for further research.

Endocrine Health in Childhood Cancer Survivors

Endocrine late effects, including reproductive disorders and secondary thyroid cancer, have been reported in up to 50 %childhood cancer survivors (CCS) more than 5 years after treatment. Most endocrine disorders are amenable to treatment; awareness of symptoms is therefore of great importance. Recognition of these symptoms may be delayed however because many are nonspecific. Timely treatment of endocrine disorders improves quality of life in CCS and prevents possible consequences, such as short stature, bone and cardiovascular disorders, and depression. At-risk CCS must therefore be regularly and systematically monitored. This article provides a summary of the most commonly reported endocrine late effects in CCS.