Radiation treatment of patients with primary pediatric malignancies: risk of developing thyroid cancer as a secondary malignancy

Risk factors for recurrence of differentiated thyroid carcinoma in children and adolescents: A retrospective cohort study

This study aimed to provide a recent clinical evaluation of the outcome of treatment and the predictors of recurrence for Chinese children and adolescents with differentiated thyroid carcinoma (DTC). This is a retrospective cohort study at the Yunnan Cancer Hospital from May 2002 to August 2021. We analyzed several risk factors related to the recurrence of DTC in children and adolescents. The Chi-square test, Kaplan-Meier log-rank tests, and Cox regression analysis were used in the statistical analysis. A P-value <.05 was considered statistically significant. A total of 103 patients were enrolled, including 68 girls (66.0%) and 35 boys (34.0%) with a median age of 18 years (range: 7-20 years). All enrolled patients received standard treatment. Children (≤14years) tended to have multifocality and higher levels of thyroid imaging reporting and data system, higher pN stage, and higher American Thyroid Association (ATA) pediatric risk compared with adolescents (P < .05). The chief complaints and clinical treatment differed between children and adolescents. During a follow-up of 6 to 239 months (average 74.7 months, median 59 months), all patients survived, but recurrence occurred in 22 patients (22.4%). The disease-free survival rates at 1, 2, 5, and 10 years were 91.2%, 78.4%, 77.1%, and 77.1%, respectively. Univariate Cox regression and log-rank tests showed that positive preoperative thyroglobulin level, bilaterality, extrathyroidal extension, high pT/pN/pM stage, and high ATA pediatric risk were the risk factors for DTC recurrence in children and adolescents. Multivariate Cox regression found that extrathyroidal extension and ATA pediatric risk were independent risk factors for the recurrence of DTC in children and adolescents. Additionally, among the 38 cases with cN0 stage, one who had bilateral, and multifocal thyroid nodules experienced recurrence, while the remaining 37 cases with cN0 stage had no recurrence. In conclusion, compared with adolescents, children present with more highly malignant disease and are more prone to metastasis. The significant risk factors associated with the recurrence of DTC in children and adolescents were positive preoperative thyroglobulin level, bilaterality, high pT/pN/pM stage, extrathyroidal extension, and high ATA pediatric risk, with the latter 2 being independent risk factors. The surgical approach for cN0 patients should be personalized taking into account invasive features.

Paediatric differentiated thyroid carcinoma: a UK National Clinical Practice Consensus Guideline

This guideline is written as a reference document for clinicians presented with the challenge of managing paediatric patients with differentiated thyroid carcinoma up to the age of 19 years. Care of paediatric patients with differentiated thyroid carcinoma differs in key aspects from that of adults, and there have been several recent developments in the care pathways for this condition; this guideline has sought to identify and attend to these areas. It addresses the presentation, clinical assessment, diagnosis, management (both surgical and medical), genetic counselling, follow-up and prognosis of affected patients. The guideline development group formed of a multi-disciplinary panel of sub-speciality experts carried out a systematic primary literature review and Delphi Consensus exercise. The guideline was developed in accordance with The Appraisal of Guidelines Research and Evaluation Instrument II criteria, with input from stakeholders including charities and patient groups. Based on scientific evidence and expert opinion, 58 recommendations have been collected to produce a clear, pragmatic set of management guidelines. It is intended as an evidence base for future optimal management and to improve the quality of clinical care of paediatric patients with differentiated thyroid carcinoma.

Thyroid cancer in children: A multicenter international study highlighting clinical features and surgical outcomes of primary and secondary tumors

BACKGROUND

Thyroid gland malignancies are rare in pediatric patients (0.7% of tumors); only 1.8% are observed in patients aged <20 years, with a higher prevalence recorded in women and adolescents. Risk factors include genetic syndromes, MEN disorders, autoimmune diseases, and exposure to ionizing radiation. Radiotherapy is also associated with an increased risk of secondary thyroid cancer. This study describes the clinical features and surgical outcomes of primary and secondary thyroid tumors in pediatric patients.

METHODS

Institutional data were collected from eight international surgical oncology centers for pediatric patients with thyroid cancer between 2000 and 2020. Statistical analyses were performed using the GraphPad Prism software.

RESULTS

Among 255 total cases of thyroid cancer, only 13 (5.1%) were secondary tumors. Primary thyroid malignancies were more likely to be multifocal in origin (odds ratio [OR] 1.993, 95% confidence interval [CI].7466-5.132, p = 0.2323), have bilateral glandular location (OR 2.847, 95% CI.6835-12.68, p = 0.2648), and be metastatic at first diagnosis (OR 1.259, 95% CI.3267-5.696, p > 0.999). Secondary tumors showed a higher incidence of disease relapse (OR 1.556, 95% CI.4579-5.57, p = 0.4525) and surgical complications (OR 2.042, 95% CI 0.7917-5.221, p = 0.1614), including hypoparathyroidism and recurrent laryngeal nerve injury. The overall survival (OS) was 99% at 1 year and 97% after 10 years. No EFS differences were evident between the primary and secondary tumors (chi-square 0.7307, p = 0.39026).

CONCLUSIONS

This multicenter study demonstrated excellent survival in pediatric thyroid malignancies. Secondary tumors exhibited greater disease relapse (15.8 vs. 10.5%) and a higher incidence of surgical complications (36.8 vs. 22.2%).

Increasing incidence and survival of paediatric and adolescent thyroid cancer in Cyprus 1998-2017: A population-based study from the Cyprus Pediatric Oncology Registry

BACKGROUND

Paediatric and adolescent thyroid cancer incidence rates are increasing in many countries. We determined incidence rates, temporal trends and survival from thyroid cancer diagnosed in childhood and adolescence in Cyprus during 1998-2017.

METHODS

Patients aged 0-19 years, diagnosed with thyroid cancer in the Pediatric Oncology Registry of Cyprus were included. Crude incidence rates, age standardized rates, time trends and overall survival were analysed. Annual rates and temporal trends were calculated using Microsoft Excel 2016 and Joinpoint regression analysis.

RESULTS

Eighty-one cases (76.5 % female, 23.5 % male) were identified. The crude rates (per 100,000 persons) were for both sexes 2.00 (95 % CI 1.61, 2.49), females 3.15 (95 % CI 2.45, 4.03) and males 0.92 (95 % CI 0.58, 1.44). The annual percentage changes of crude and standardised rates were 7.5 % (p < 0.05) and 7.6 % (p < 0.05). The annual percentage changes of crude rates were for females 5.1 % (p = 0.1), males 8.4 % (p < 0.05) and 15-19-year-olds 7.6 % (p < 0.05). The female to male rate ratio was 3.42 (95 % CI 2.06, 5.74). Papillary thyroid carcinoma represented 86.4 % of all cases. There was only one case after previous cancer therapy. The rate ratio of 2nd (2008-2017) to 1st (1998-2007) periods for metastatic (regional) stages was 3.76 (95 % CI 1.74, 8.31). Survival until 2018 was 100 %.

CONCLUSION

This population-based study demonstrated that thyroid cancer incidence rates in 0-19-year-olds in Cyprus was among the world's highest. Increasing trends mainly affected males and females aged 15-19 years with papillary thyroid carcinoma, the dominant type. Cases after previous cancer therapy didn't contribute to increasing rates. The increase of metastatic cases suggests a true increase of thyroid cancer rather than overdiagnosis. Although prognosis is excellent with 100 % survival, the rising incidence rate is unexplained, indicating the need to identify causes.

Thyroid Sequelae of Pediatric Cancer Therapy

The hypothalamic-pituitary-thyroid axis is a common site of unintended, acquired disease either during or after the treatment of cancer. Children treated with external radiation therapy are at the highest risk for developing a thyroid-related late effect, but thyroid dysfunction and second primary thyroid neoplasms can also occur after treatment with radiopharmaceutical agents such as 131I-metaiodobenzylguanidine. Increasingly recognized is the development of early thyroid dysfunction as an off-target consequence of the more novel cancer therapeutics such as the tyrosine kinase inhibitors and immune checkpoint inhibitors. Thyroid sequelae resulting from irradiation may manifest only after years to decades of follow-up, and their resultant clinical symptoms may be indolent and non-specific. Therefore, lifelong monitoring of the childhood cancer survivor at risk for thyroid disease is paramount. In this comprehensive review, the myriad thyroid adverse effects resulting from pediatric cancer treatment are discussed and an overview of screening and treatment of these thyroid sequelae provided.

Thyroid Cancer in the Pediatric Population

Thyroid cancer is rare in the pediatric population, but thyroid carcinomas occurring in children carry a unique set of clinical, pathologic, and molecular characteristics. In comparison to adults, children more often present with aggressive, advanced stage disease. This is at least in part due to the underlying biologic and molecular differences between pediatric and adult thyroid cancer. Specifically, papillary thyroid carcinoma (which accounts for approximately 90% of pediatric thyroid cancer) has a high rate of gene fusions which influence the histologic subtypes encountered in pediatric thyroid tumors, are associated with more extensive extrathyroidal disease, and offer unique options for targeted medical therapies. Differences are also seen in pediatric follicular thyroid cancer, although there are few studies of non-papillary pediatric thyroid tumors published in the literature due to their rarity, and in medullary carcinoma, which is most frequently diagnosed in the pediatric population in the setting of prophylactic thyroidectomies for known multiple endocrine neoplasia syndromes. The overall shift in the spectrum of histotypes and underlying molecular alterations common in pediatric thyroid cancer is important to recognize as it may directly influence diagnostic test selection and therapeutic recommendations.

Radiotherapy for childhood cancer and subsequent thyroid cancer risk: a systematic review

Most of the pooled analyses and reviews reported an association between radiotherapy for childhood cancer and an increased thyroid cancer risk. Up to now this article presents the first systematic literature review on this association combined with a critical assessment of the methodological quality of the included articles. PubMed and Web of Science databases were searched for relevant articles until May 2016. We included peer-reviewed cohort and case-control studies that investigated an association between radiotherapy for childhood cancer and the occurrence of subsequent thyroid cancer. A systematic overview is presented for the included studies. We identified 17 retrospective cohort studies, and four nested case-control studies, representing 100,818 subjects. The age range at first cancer diagnosis was 0-25.2 years. Considerable variability was found regarding study sizes, study design, treatment strategies, dose information, and follow-up periods. 20 of the 21 identified studies showed increased thyroid cancer risks associated with childhood radiation exposure. The large majority showed an increased relative risk or odds ratio confirming the association between radiotherapy and thyroid cancer although the variation in results was large. Additionally to a pooled analysis that has been published recently, we systematically included 17 further studies, which allowed us to cover information from countries that were not covered by large-scale childhood cancer survivor studies. The methodological limitations of existing studies and inconsistencies in findings across studies yielded a large study heterogeneity, which made a detailed comparison of study results difficult. There is a need to strengthen standardisation for reporting.

Age at Primary Malignancy Determines Survival in Adolescent and Young Adults That Develop a Secondary Thyroid Cancer

PURPOSE

Second malignancy status is a risk factor for death in adolescent and young adults (AYAs) (ages 15-39) with thyroid cancer (TC). This study investigates whether age at primary malignancy (PM) is an independent predictor of overall survival (OS) for AYA patients diagnosed with secondary TC who have survived ≥5 years from their PM.

METHODS

Surveillance, Epidemiology and End Results program (SEER) multiple-primary session (SEER-9 [1973-2010] and SEER-13 [1992-2010]) identified all secondary TCs in patients <40 years of age who were also 5-year survivors. Patients with a thyroid second malignant neoplasm (SMN) diagnosed as an AYA were categorized by age at PM (pediatric <15 years vs. AYA). Kaplan-Meier and Cox proportional analysis determined OS.

RESULTS

Four hundred twenty-eight cases of secondary AYA TCs in 5-year cancer survivors were identified; 71 had a pediatric PM and 357 an AYA PM. Median OS after a pediatric PM was 35.76 years and 33.22 years after an AYA-PM (p = 0.023); only one death was due to TC. Race, site and stage of PM, marital status, and three or more independent PMs also influenced OS (all p < 0.05). However, TC characteristics, stage, and treatment did not affect OS. Cox regression demonstrated that patients with an AYA PM had a 5.84 relative risk of death (95% confidence interval [95% CI]: 1.81-18.91) compared to patients with a pediatric PM. Among AYAs who develop a TC as a second PM, OS is not affected by the TC. The OS for these patients is associated with their demographics and the characteristics of their PM: patients who are black, male, have three or more primary cancers, and a higher stage of their first malignancy are more likely to die.

CONCLUSION

For AYA patients with thyroid SMNs, having a prior AYA PM (compared to a pediatric PM), Black race, and having three or more independent tumors predicted a decreased OS, independent of PM type or PM/SMN stage.

Pediatric thyroid nodules and malignancy

Proper management of pediatric thyroid nodules is crucial to achieving good outcomes. It is important to obtain a thorough history, including prior radiation exposure and family history of thyroid cancer and any symptoms of hypothyroidism or hyperthyroidism. A complete physical examination with special attention to the thyroid gland and any cervical lymphadenopathy is important. Nodules between 5 and 10 mm with risk factors (clinical or sonographic) and all nodules greater than 10 mm should undergo a fine-needle aspiration biopsy. A comprehensive center of pediatric specialists is the best environment for treatment of these patients.

Acquired disorders of the thyroid following treatment for head and neck cancer

The multimodality management of head and neck cancer routinely utilizes radiation therapy in treatment. The hypothalamus, pituitary and thyroid gland may be included within treatment fields. The incidence of human papilloma virus-associated oropharyngeal carcinoma has seen a dramatic increase over the last 3 decades. Current guidelines for the long-term aftercare assessment advocate only for thyroid-stimulating hormone levels every 6-12 months after baseline posttreatment imaging. With a growing population of younger patients with a favorable prognosis exposed to therapeutic radiation therapy, it is anticipated that incidence of thyroid-associated complications, such as hypothyroidism and thyroid cancer, could increase significantly over time. Constructing a strategy for the long-term reassessment of these patients beyond existing guidelines may be necessary.