Thyroid functions in long-term survivors of pediatric Hodgkin's lymphoma treated with chemotherapy and radiotherapy

Primary Hypothyroidism in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review

PURPOSE

From the Pediatric Normal Tissue Effects in the Clinic (PENTEC) initiative, a systematic review and meta-analysis of publications reporting on radiation dose-volume effects for risk of primary hypothyroidism after radiation therapy for pediatric malignancies was performed.

METHODS AND MATERIALS

All studies included childhood cancer survivors, diagnosed at age <21 years, whose radiation therapy fields exposed the thyroid gland and who were followed for primary hypothyroidism. Children who received pituitary-hypothalamic or total-body irradiation were excluded. PubMed and the Cochrane Library were searched for studies published from 1970 to 2017. Data on age at treatment, patient sex, radiation dose to neck or thyroid gland, specific endpoints for hypothyroidism that were used in the studies, and reported risks of hypothyroidism were collected. Radiation dose-volume effects were modeled using logistic dose response. Relative excess risk of hypothyroidism as a function of age at treatment and sex was assessed by meta-analysis of reported relative risks (RR) and odds ratios.

RESULTS

Fifteen publications (of 1709 identified) were included for systematic review. Eight studies reported data amenable for dose-response analysis. At mean thyroid doses of 10, 20, and 30 Gy, predicted rates of uncompensated (clinical) hypothyroidism were 4%, 7%, and 13%, respectively. Predicted rates of compensated (subclinical) hypothyroidism were 12%, 25%, and 44% after thyroid doses of 10, 20, and 30 Gy, respectively. Female sex (RR = 1.7, P < .0001) and age >15 years at radiation therapy (RR = 1.3, P = .005) were associated with higher risks of hypothyroidism. After a mean thyroid dose of 20 Gy, predicted risks of hypothyroidism were 13% for males <14 years of age, increasing to 29% for females >15 years of age.

CONCLUSION

A radiation dose response for risk of hypothyroidism is evident; a threshold radiation dose associated with no risk is not observed. Thyroid dose exposure should be minimized when feasible. Data on hypothyroidism after radiation therapy should be better reported to facilitate pooled analyses.

Late effects in pediatric Hodgkin lymphoma survivors after uniform treatment with ABVD with or without radiotherapy

PURPOSE

ABVD (doxorubicin, bleomycin,vinblastine, and dacarbazine) is not a standard regimen in children due to concerns regarding late effects. However, no studies have evaluated long-term toxicities of ABVD in children.

METHODS

Total 154 pediatric Hodgkin lymphoma (HL) survivors uniformly treated with ABVD were clinically followed up as per institutional protocol. All participants were evaluated for cardiac, pulmonary, and thyroid function abnormalities by multigated acquisition scan (MUGA) scan, spirometry with diffusion capacity of lung for the uptake of carbon monoxide (DLCO), and thyroid profile test, respectively, at a single time point. Predictors of toxicity were also analyzed.

RESULTS

The median duration of follow-up of the cohort was 10.3 years (6.04-16.8). No secondary malignant neoplasm (SMN) or symptomatic cardiac/pulmonary toxicities were detected. Nine patients (5.9%) had left ventricular ejection fraction (LVEF) <55%. Subclinical and overt hypothyroidism were observed in 78 (50.6%) and 16 (10.4%) survivors, respectively. Abnormal spirometry and reduced DLCO was observed in 43.2% and 42.0% survivors, respectively. Receiving neck radiation was significantly associated with thyroid dysfunction (odds ratio [OR] 16.04, p < .001); age ≥10 years predicted reduced DLCO (OR 4.12, p = .001). Sixty-three and 33 patients had one and two late adverse effects, respectively; receiving neck radiation predicted development of multiple late effects (proportional OR 4.72, p < 0.001). Cumulative dose of chemotherapy did not predict toxicity.

CONCLUSIONS

Overall, ABVD appears safe in children at a relatively short follow-up. Long-term safety data are required before it can be adopted for treating pediatric HL patients. Children receiving neck radiation require close follow-up.

The Continuum of Thyroid Disorders Related to Immune Checkpoint Inhibitors: Still Many Pending Queries

BACKGROUND

Until more data are available to shed light on the thyroid disorders related to immune checkpoint inhibitors (ICPi) implemented for the treatment of hematological malignancies, the decision-making is guided by pertinent data derived mostly from solid tumors.

METHODS

The present review provides a comprehensive and updated overview of the thyroid disorders related to ICPi, namely to inhibitors of cytotoxic T-lymphocyte antigen 4 (CTLA-4), programmed cell death (PD) 1 (PD-1), and the ligand of the latter (PD-L1).

RESULTS

With the increasing recognition of ir thyroid disorders, many outstanding issues have emerged. Ir thyroid disorders are reminiscent of, but not identical to, thyroid autoimmunity. Interclass and intraclass ICPi differences regarding thyroid immunotoxicity await interpretation. The available data concerning the predictive value of thyroid autoantibodies for the development of ir thyroid disorders are inconclusive. Mounting data indicate an association of ir thyroid disorders with ICPi efficacy, but a causative link is still lacking. The path forward is a tailored approach, entailing: (i) the validation of tumor-specific, patient-specific, and ICPi-specific predictive factors; (ii) appropriate patient selection; (iii) the uncoupling of antitumor immunity from immunotoxicity; (iv) a multidisciplinary initiative; and (v) global registry strategies.

CONCLUSIONS

Untangling and harnessing the interrelationship of immuno-oncology with endocrinology underlying the ir thyroid disorders will yield the optimal patient care.

Clinical Characteristics and Treatment Outcomes in Children, Adolescents, and Young-adults with Hodgkin's Lymphoma: a KPHOG Lymphoma Working-party, Multicenter, Retrospective Study

BACKGROUND

Hodgkin's lymphoma (HL) constitutes 10%-20% of all malignant lymphomas and has a high cure rate (5-year survival, around 90%). Recently, interest has increased concerning preventing secondary complications (secondary cancer, endocrine disorders) in long-term survivors. We aimed to study the epidemiologic features and therapeutic outcomes of HL in children, adolescents, and young adults in Korea.

METHODS

We performed a multicenter, retrospective study of 224 patients aged < 25 years diagnosed with HL at 22 participating institutes in Korea from January 2007 to August 2016.

RESULTS

A higher percentage of males was diagnosed at a younger age. Nodular sclerosis histopathological HL subtype was most common, followed by mixed cellularity subtype. Eighty-one (36.2%), 101 (45.1%), and 42 (18.8%) patients were classified into low, intermediate, and high-risk groups, respectively. Doxorubicin, bleomycin, vinblastine, dacarbazine was the most common protocol (n = 102, 45.5%). Event-free survival rate was 86.0% ± 2.4%, while five-year overall survival (OS) rate was 96.1% ± 1.4%: 98.7% ± 1.3%, 97.7% ± 1.6%, and 86.5% ± 5.6% in the low, intermediate, and high-risk groups, respectively (P = 0.021). Five-year OS was worse in patients with B-symptoms, stage IV disease, high-risk, splenic involvement, extra-nodal lymphoma, and elevated lactate dehydrogenase level. In multivariate analysis, B-symptoms and extra-nodal involvement were prognostic factors for poor OS. Late complications of endocrine disorders and secondary malignancy were observed in 17 and 6 patients, respectively.

CONCLUSION

This is the first study on the epidemiology and treatment outcomes of HL in children, adolescents, and young adults in Korea. Future prospective studies are indicated to develop therapies that minimize treatment toxicity while maximizing cure rates in children, adolescents, and young adults with HL.

Hodgkin Lymphoma in Children and Adolescents: Advances in Pathology, Diagnosis, and Treatment Strategies

Strategies used for the treatment of children with Hodgkin lymphoma (HL) over the last four decades have resulted in excellent long-term survivals. However, the short- and long-term treatment-associated morbidities were high. In an attempt to reduce complications, the current treatment strategies apply initial risk stratification principles based on certain host and tumor risk factors to help assign patients to the appropriate risk group and tailor therapy based on response to chemotherapy (CTR). Radiotherapy (RT) was only given to certain groups of patients who show suboptimal response to CTR. Enrollment of patients in clinical trials allowed testing newer treatment strategies, which has improved the outcome significantly. High-dose CTR with stem cell support remains the mainstay of treatment for relapsed and refractory HL. Newer targeted medications are being increasingly used for the treatment of patients with relapsed and refractory HL, but results are variable. In this review report, we give extensive account about the pathophysiology, clinical presentation, histopathological diagnosis, modern investigation techniques, the most recent risk adapted treatment strategies, and the use and effect of novel medications. In addition, we discuss in details the short- and long-term therapy-related complications and future prospects in the management of HL.

Thyroid hormone therapy in congenital hypothyroidism and pediatric hypothyroidism

The evaluation and management of hypothyroidism in children are similar to adults, but there are important differences based on the dependence on normal thyroid function for neurocognitive and physical development. In the pediatric population, hypothyroidism is frequently categorized as congenital or acquired hypothyroidism, depending on the age of presentation and the underlying etiology. The evaluation and management of children and adolescents with hypothyroidism are determined by the etiology as well as by the age at diagnosis, severity of the hypothyroidism, and the response to thyroid hormone replacement therapy. Children and adolescents require higher weight-based doses for thyroid hormone replacement than do adults, likely due to a shorter half-life of thyroxine (T4) and triiodothyronine (T3) in children, but weight-based dose requirements decrease as the child advances into adulthood. Multiple gaps in knowledge remains regarding how to optimize the treatment of hypothyroidism in pediatric patients, including (but not limited to) the selection of patients with subclinical hypothyroidism for treatment, and the potential benefit of combined LT3/LT4 therapy for patients with persistent symptoms and/or low T3 on LT4 monotherapy. The life-long impact on growth and development, and potentially on long-term cardiovascular and psychosocial health, are significant and highlight the importance of future prospective studies in pediatric patients to explore these areas of uncertainty.

Comparison of Thyroid Nodule Prevalence by Ultrasound in Childhood Cancer Survivors With and Without Thyroid Radiation Exposure

PURPOSE

Children receiving radiotherapy of the head, neck, or chest as treatment of primary malignancies are at increased risk for secondary thyroid malignancy. We hypothesized that current standards (yearly thyroid physical examination) lead to a substantial number of missed thyroid nodules. Our objectives were: (1) use thyroid ultrasound to assess thyroid nodules in childhood cancer survivors; and (2) compare prevalence of thyroid nodules in thyroid radiation-exposed patients as compared with cancer survivors without radiation exposure.

METHODS

We recruited 60 patients with thyroid radiation and chemotherapy exposure (median age at cancer diagnosis 10.8 y) and 59 patients with chemotherapy exposure alone (median age at diagnosis 4.3 y) from our long-term survivorship clinics. Each patient had a thyroid physical examination and thyroid ultrasound performed.

RESULTS

Thirty-three patients (27.7%) had nodules >0.3 cm of which 2 were palpated (6.1%). We found 22 radiated patients (36.7%) with nodules versus 11 nonradiated patients (18.6%) (P=0.03). Eleven patients were biopsied and 1 diagnosis of secondary papillary thyroid carcinoma was confirmed.

CONCLUSION

Our study supports further examination of incorporating thyroid ultrasounds into long-term survivorship follow-up guidelines in radiation-exposed patients for the detection of thyroid nodules and secondary malignancies.

Ultrasound Evaluation of Thyroid Gland Pathologies After Radiation Therapy and Chemotherapy to Treat Malignancy During Childhood

PURPOSE

The purpose of this study was to evaluate correlations between treatment of malignancy by radiation therapy during childhood and the occurrence of thyroid gland pathologies detected by ultrasonography in follow-up examinations.

METHODS AND MATERIALS

Reductions of thyroid gland volume below 2 standard deviations of the weight-specific mean value, occurrence of ultrasonographically detectable thyroid gland pathologies, and hypothyroidism were retrospectively assessed in 103 children and adolescents 7 months to 20 years of age (median: 7 years of age) at baseline (1997-2013) treated with chemoradiation therapy (with the thyroid gland dose assessable) or with chemotherapy alone and followed by ultrasonography and laboratory examinations through 2014 (median follow-up time: 48 months).

RESULTS

A relevant reduction of thyroid gland volume was significantly correlated with thyroid gland dose in univariate (P<.001) and multivariate analyses for doses above 2 Gy. Odds ratios were 3.1 (95% confidence interval: 1.02-9.2; P=.046) for medium doses (2-25 Gy) and 14.8 (95% confidence interval: 1.4-160; P=.027) for high doses (>25 Gy). Thyroid gland dose was significantly higher in patients with thyroid gland pathologies during follow-up (P=.03). Univariate analysis revealed significant correlations between hypothyroidism and thyroid gland dose (P<.001).

CONCLUSIONS

Ultrasonographically detectable changes, that is, volume reductions, pathologies, and hypothyroidism, after malignancy treatment during childhood are associated with thyroid gland dose. Both ultrasonography and laboratory follow-up examinations should be performed regularly after tumor therapy during childhood, especially if the treatment included radiation therapy.

Controversies in the role of radiotherapy in the treatment of pediatric Hodgkin lymphoma

Hodgkin lymphoma in children is a highly curable malignancy with current approaches utilizing combined modality therapy and a risk-adapted approach. The combination of anthracyclines, bleomycin, and radiotherapy, as well as other alkylating agents, are significant risk factors for secondary malignancies and cardiopulmonary toxicity. Therefore, current strategies aim to optimize cure rates while minimizing late effects. The role of radiotherapy has been examined in recent pediatric trials, with varying results. However, they provide evidence, as a whole, for the omission of radiotherapy for a subgroup of patients, without compromising outcomes.