Ultrasound-detected thyroid nodules in radiation-exposed patients: changes over time

Systematic review and meta-analysis of ultrasonic elastography in the diagnosis of benign and malignant thyroid nodules

Background

In recent years, ultrasound elastography (USE) has been the main diagnostic technique for benign and malignant thyroid nodules. However, it cannot display the blood flow signals of nodules with smaller diameters clearly, which decreases its diagnostic accuracy.

Methods

Chinese and English databases were searched using "ultrasonic elastography", "benign and malignant thyroid nodules", and "diagnose" as the search terms. RevMan 5.3 software was used for meta-analysis.

Results

A total of 11 randomized controlled trials (RCTs) were included. Eight articles analyzed clinical symptoms, and the heterogeneity test results were Chi² =7.46, df=7, I²=6%, and P=0.38; and Z=11.44, OR =14.58, 95% confidential interval (CI): 9.21-23.07, and P<0.01. The diagnostic efficacy of USE was analyzed in 8 articles, and the heterogeneity test results were Chi² =3.03, df=7, I²=0%, and P=0.88; and Z=6.33, OR =7.47, 95% CI: 4.01-13.93, and P<0.01. The pathological diagnosis results of randomized controlled trials were analyzed in 10 literatures, and the heterogeneity test results were Tau² =0.78, Chi² =20.97, df=9, I²=57%, and P=0.01; and Z=7.27, OR =14.67, 95% CI: 7.11-30.27, and P<0.01. After meta-analysis, the combined sensitivity was 72.26% (95% CI: 0.625-0.764) and the combined specificity was 95.35% (95% CI: 0.815-0.943). The area under the receiver operating characteristic curve (AUC) was 0.857.

Conclusions

This meta-analysis confirmed that USE shows high sensitivity and specificity in diagnosing benign and malignant thyroid nodules, which could reduce the false negative rate (FNR) and false positive rate (FPR), showing high clinical diagnostic value.

Comparative Analysis of the Growth Pattern of Thyroid Cancer in Young Patients Screened by Ultrasonography in Japan After a Nuclear Accident: The Fukushima Health Management Survey

IMPORTANCE

Thyroid cancer generally grows at a very slow rate in adults, and overdiagnosis is a global issue. However, the detection of early-stage thyroid cancer by screening is not well described in young patients. To prevent overdiagnosis, it is essential to understand the natural course of thyroid cancer growth detection by ultrasonography screening in young patients.

OBJECTIVE

To evaluate the natural progression of thyroid cancer in young patients.

DESIGN, SETTING, AND PARTICIPANTS

An observational study evaluated changes in the diameter of malignant or suspected malignant thyroid tumors on 2 occasions. Changes in malignant thyroid tumor diameter were estimated during the observation period between the screening and confirmatory examinations in the first-round thyroid ultrasonography examination of the Fukushima Health Management Survey in patients younger than 21 years after a nuclear accident at a power plant in Fukushima, Japan. In total, 116 patients cytologically diagnosed with or suspected to have thyroid cancer were classified into 3 groups based on a greater than 10% reduction, a change of -10% to +10% in diameter, and a greater than 10% increase in tumor diameter. The association between tumor growth rate and tumor diameter was analyzed. The study was conducted from March 1, 2016, to August 6, 2017.

MAIN OUTCOMES AND MEASURES

Tumor volume changes, the coefficient of growth of thyroid cancer in young patients, and the association between the observation period or tumor diameter and them.

RESULTS

Of 116 patients, 77 were female; the mean age was 16.9 years (median, 17.5 years). The mean observation period was 0.488 (range, 0.077-1.632) years. No significant differences in age, sex, tumor diameter, observation period, or serum levels of thyrotropin and thyroglobulin were observed among the groups. Whereas tumor volume changes were not linearly correlated with the observation period (Pearson R = 0.121; 95% CI, -0.062 to 0.297), the coefficient of growth was significantly and negatively correlated with the tumor diameter in the screening examination (Spearman ρ = -0.183; 95% CI, -0.354 to -0.001), suggesting growth arrest after the initial proliferation phase.

CONCLUSIONS AND RELEVANCE

Ultrasonography screening could reveal asymptomatic thyroid cancer that is falling into a growth arrest pattern in many young patients. Considering the long life expectancy, prevention of overdiagnosis necessitates careful long-term monitoring without immediate diagnosis for suspected noninvasive thyroid cancer.

Patients exposed to diagnostic head and neck radiation for the management of shunted hydrocephalus have a significant risk of developing thyroid nodules

PURPOSE

External radiation to the head and neck can lead to an increased incidence of thyroid nodules. We investigated whether patients requiring repeated head and neck imaging for the management of shunted hydrocephalus had a higher incidence of ultrasound-detected thyroid nodules compared to reports of comparable age.

METHODS

Patients treated at our institution for shunted hydrocephalus from 1990 to 2003 were contacted. Enroled patients underwent a thyroid ultrasound. Demographic data and radiation exposure history were obtained retrospectively.

RESULTS

Thyroid nodules were identified sonographically in 15/112 patients (13.6 %). Patients with thyroid nodules were older (mean 24.3 ± 7.6 years) than those without (mean 18.4 ± 8.0 years) (p = 0.005). Those with a detectable thyroid nodule had a longer follow up time compared to those who did not (mean 21.9 ± 5.5 vs. 15.1 ± 7 years, respectively) (p = 0.018).

CONCLUSION

Patients with shunted hydrocephalus are exposed to substantial head and neck radiation from diagnostic imaging and have a higher incidence of thyroid nodules detected by ultrasonography. These patients should be provided ongoing surveillance for detection of thyroid nodules and the possibility of malignancy.

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.

Sonographic appearance of thyroid glands in patients treated with intensity-modulated radiotherapy or conventional radiotherapy for nasopharyngeal carcinoma

BACKGROUND

This study aimed to investigate the sonographic appearances of the thyroid glands in nasopharyngeal carcinoma (NPC) patients whose cervical lymph nodes were treated with conventional radiotherapy (RT) or intensity-modulated radiotherapy (IMRT). The post-RT sonographic appearances of the thyroid glands in NPC patients were also correlated with the thyroid function.

METHODS

One hundred and three NPC patients who had completed RT of cervical lymph nodes using the anterior cervical field, 30 NPC patients who had completed RT of cervical lymph nodes using IMRT, and 61 healthy subjects were included in the study. Thyroid glands were sonographically assessed for their size, echogenicity, vascularity, and internal architecture. Thyroid function tests were also performed on each subject.

RESULTS

In comparison with the patients with abnormal thyroid function, the thyroid glands of the patients with normal thyroid function tended to be homogeneous and to have greater volume and echogenicity index (p < 0.05). Compared with those of the healthy subjects, the thyroid glands of patients previously treated with IMRT and those treated with the anterior cervical field showed significantly lower thyroid volume, lower incidence and number of nodules, and higher vascularity index (p < 0.05).

CONCLUSIONS

The patient's history of previous RT should be taken into consideration in the sonographic examination of the thyroid gland post-RT. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 43:210-223, 2015.

Thyroid nodules

According to the literature, thyroid nodules (TNs) are quite rare in the first two decades of life and are predominantly non-cancerous, although cancerous TNs are more common in the first two decades of life than in adults. Therefore, it is important for clinicians to distinguish benign from malignant lesions preoperatively because the latter require a total thyroidectomy with or without neck lymph node dissection. A careful work-up and a fine-needle aspiration biopsy (FNAB) are mandatory to improve the preoperative diagnosis. High-resolution thyroid ultrasound and real-time elastosonography are adjuvant presurgical tools in selecting patients for surgery, particularly those with indeterminate or non-diagnostic cytology. Elevated thyroid-stimulating hormone (TSH) level in a patient with a thyroid nodule is a new laboratory predictor of thyroid cancer risk. The majority of thyroid carcinomas derive from the follicular cell, whereas medullary thyroid carcinoma (MTC) derives from calcitonin-producing cells. Patients with MTC are screened for germ-line RET mutations to detect carriers and identify family members for prophylactic or therapeutic thyroidectomy.

Surveillance following head, neck, and chest radiotherapy: thyroid ultrasound monitoring for secondary thyroid malignancy

Children who receive head, neck, or chest radiotherapy for various primary malignancies have increased risk for secondary thyroid malignancy. Thyroid nodules are difficult to identify by physical examination and/or laboratory tests. Thyroid ultrasound can detect non-palpable nodules without adverse side effects. We performed a retrospective chart review of 36 patients who received radiotherapy and underwent thyroid ultrasound. Forty-seven percent (n = 17) had ≥1 nodule(s) detected. Seven patients underwent thyroidectomy; four of whom were diagnosed with thyroid malignancy. Our study suggests routine use of thyroid ultrasound in high-risk patients detects subclinical thyroid nodules and potential thyroid malignancy post-radiotherapy.

[Thyroid disorders associated with external radiation in children and adolescents]

The effects of ionizing radiation on the thyroid have been studied for several decades, and nuclear accidents are the major source of information about the subject. There is an association of hypothyroidism, hyperthyroidism, thyroid nodules and cancer with radiation, but the threshold dose, mechanism of injury, and some risk factors have not been fully established. Children are more susceptible to thyroid injury caused by radiation and require prolonged follow-up after exposure. This issue is especially relevant nowadays, since a large number of people treated with radiation for childhood cancer survive and may have sequelae. Diagnostic radiology tests also represent a source of exposure to radiation in the pediatric population. In this review, we analyze different clinical and pathological changes, and the mechanisms of thyroid lesions caused by radiotherapy and computed tomography in children and adolescents. It is important to understand these data for prevention, early detection, and treatment of thyroid dysfunction.

Exposing the thyroid to radiation: a review of its current extent, risks, and implications

Radiation exposure of the thyroid at a young age is a recognized risk factor for the development of differentiated thyroid cancer lasting for four decades and probably for a lifetime after exposure. Medical radiation exposure, however, occurs frequently, including among the pediatric population, which is especially sensitive to the effects of radiation. In the past, the treatment of benign medical conditions with external radiation represented the most significant thyroid radiation exposures. Today, diagnostic medical radiation represents the largest source of man-made radiation exposure. Radiation exposure related to the use of computerized tomography is rising exponentially, particularly in the pediatric population. There is direct epidemiological evidence of a small but significant increased risk of cancer at radiation doses equivalent to computerized tomography doses used today. Paralleling the increasing use of medical radiation is an increase in the incidence of papillary thyroid cancer. At present, it is unclear how much of this increase is related to increased detection of subclinical disease from the increased utilization of ultrasonography and fine-needle aspiration, how much is due to a true increase in thyroid cancer, and how much, if any, can be ascribed to medical radiation exposure. Fortunately, the amount of radiation exposure from medical sources can be reduced. In this article we review the sources of thyroid radiation exposure, radiation risks to the thyroid gland, strategies for reducing radiation exposure to the thyroid, and ways that endocrinologists can participate in this effort. Finally, we provide some suggestions for future research directions.

Frequency of undetected thyroid nodules in a large I-131-exposed population repeatedly screened by ultrasonography: results from the Ukrainian-American cohort study of thyroid cancer and other thyroid diseases following the Chornobyl accident

BACKGROUND

Imperfect detection on screening tests can lead to erroneous conclusions about the natural history of thyroid nodules following radiation exposure. Our objective was to assess in a repeatedly screened I-131-exposed population the frequency with which a thyroid nodule could be retrospectively identified on ultrasonography studies preceding the one on which it was initially detected.

METHODS

A cohort of over 13,000 young people exposed to fallout from Chornobyl underwent ultrasonography screening at 2-year intervals from 1998 to 2007. The study group consisted of screening examinations on which a thyroid nodule was detected following one or more prior negative examinations. In the study group there were 48 cancers and 92 benign nodules. For each of these 140 index studies a comparison set was created containing all available prior studies plus (to test for bias) negative studies from control subjects. While viewing the index study, three independent reviewers scored the comparison studies for the presence and size of a preexisting nodule. Detection rates were compared for true priors versus controls, for cancer versus benign, and for histologic subtypes of papillary carcinoma.

RESULTS

A preexisting nodule was identified by at least one reviewer in 24.0% of the true prior versus 8.3% of the controls and by all three reviewers in 11% versus 1% (Fisher's exact test, p < 0.0001). There was no significant difference in detection rates between cancers and benign nodules (22.4% vs. 24.7%, p = 0.411). There was no correlation between time from prior to index study and change in nodule size for either malignant or benign nodules (r = 0.01, NS). There were no differences in detection rates or size among papillary cancer subtypes. Reviewers could not distinguish between true priors and controls.

CONCLUSIONS

These findings, showing significant rates of undetected benign and malignant nodules and no evidence for rapid growth, suggest that conclusions drawn from screening studies about the frequency of late-developing, rapidly growing thyroid nodules following radiation exposure should be interpreted with caution.

The shrinking thyroid: how does thyroid size change following radiation therapy for laryngeal cancer?

BACKGROUND AND PURPOSE

External beam radiation therapy (XRT) for head and neck cancer is known to induce hypothyroidism and cause morphologic changes in the thyroid gland. This retrospective study investigates change in the size of the thyroid gland detectable by CT after XRT for laryngeal cancer.

MATERIALS AND METHODS

The measured width of the thyroid lobes in 61 patients treated nonsurgically with XRT for laryngeal cancer between 2000 and 2003 on posttherapy CT was compared with that on pretherapy CT. Absolute and percentage changes in measured thyroid width following XRT were analyzed according to chemotherapy administration and posttherapy thyroid function.

RESULTS

Eighty-five percent (52/61) of patients had a decrease in the width of the thyroid gland. The average change in width measuring -4.7 mm and -13.8% (SD, 5.7 mm and 19.9%) occurred at an average of 758 days following completion of XRT (mean, 402-1534 days) and was significant (P = .002). Average change in width between hypothyroid patients (n = 19, -6.1 mm and -20.0% change) and euthyroid patients (n = 42, -4.1 mm and -11.1% change) was not significant (P = .20 absolute change and P = .11 percentage change). The average change in width between patients receiving chemotherapy (n = 31, -5.5 mm and -16.1% change) and patients not receiving chemotherapy (n = 30, -3.9 mm and -11.5% change) was not significant (P = .26 absolute change and P = .37 for percentage change).

CONCLUSIONS

Most nonsurgical patients receiving XRT for laryngeal cancer have a significant decrease in the width of their thyroid glands detected on CT. The average change in the size of the thyroid gland does not differ when development of hypothyroidism or chemotherapy administration are considered.

Factors related to the recurrence of thyroid nodules after surgery for benign radiation-related nodules

OBJECTIVE

Benign thyroid nodules are increased by radiation exposure and recurrences are common. The goal of this study was to determine the factors related to recurrence of nodular disease and the efficacy of thyroid hormone therapy in reducing them.

DESIGN, SETTING, AND SUBJECTS

The study population was drawn from a cohort of 4296 people treated before the age of 16 with conventional external radiation for benign conditions of the head and neck between 1939 and the early 1960s. The study group consisted of 632 subjects who had benign nodules removed surgically. At the discretion of their physicians, 426 subjects were treated with thyroid hormone after surgery, 198 were not, and in 8 subjects, thyroid hormone treatment status was unknown.

MAIN OUTCOMES

There were 129 (20.4%) subjects who developed new nodules during follow-up. Women had a greater risk of recurrent nodules than men (27.5% vs. 13.5%) and the rate of recurrence correlated inversely with the extent of surgery. The group who took thyroid hormone had a lower recurrence rate than the untreated group (14.2% vs. 34.2%). The risk of recurrence was reduced to 0.69 (0.47-1.01) in thyroid hormone-treated subjects, regardless of extent of surgery, and to 0.66 (0.46-0.97) when only the subjects with less than 75% of their thyroid removed were considered.

CONCLUSION

Thyroid hormone therapy reduced recurrences in this irradiated cohort. It should be recommended to all patients with irradiated thyroids and previous thyroid surgery.

Long-term risks for thyroid cancer and other neoplasms after exposure to radiation

Radiation-related thyroid cancer continues to be a clinical concern for two reasons: the risks associated with the widespread use of radiation treatments for benign conditions in the middle of the last century persist for decades after exposure; and radiation continues to be an effective component of the treatment of several childhood malignancies. Patients who were irradiated in the head and neck area need to be evaluated for thyroid cancer, benign thyroid nodules, hyperparathyroidism, salivary-gland neoplasms and neural tumors, including acoustic neuromas. Radiation-related thyroid cancers appear to have the same clinical behavior as other thyroid cancers, but many irradiated patients are entering the age range when more aggressive neoplasms occur. In this paper, we review how to approach the clinical management of a patient with a history of radiation exposure in the thyroid area, and how to treat radiation-exposed patients who develop related neoplasms, especially thyroid cancer.

Thyroid disorders in employees of a nuclear power plant

BACKGROUND

The thyroid gland is a potential target organ for radiation-related damage. The aim of this analysis was to investigate the association between occupational exposure to ionizing radiation and the risk of autoimmune thyroid disease as well as thyroid nodules and dysfunction in workers of a former nuclear power station.

METHODS

Seventy-one male power station workers 38 to 57 years of age who had been exposed to a lifetime dose in the upper allowed range (accumulated lifetime dose 70 to 400 mSv) were compared to a population-based sample of 670 males who were not exposed to occupational radiation. Thyroid ultrasound was performed by the same observers. Laboratory parameters were analyzed in a central laboratory.

RESULTS

After controlling analyses for age and further relevant confounders no significant differences with respect to thyroid nodules and markers of autoimmune thyroid disease were detected between exposed and nonexposed individuals. However, nuclear power plant employees had higher odds for elevated serum thyrotropin (TSH) levels than the reference group (odds ratio 4.54; 95% confidence interval 1.43; 13.91).

CONCLUSIONS

Workers of a nuclear power plant with occupational exposure to ionizing radiation within the upper allowed dose range have an increased risk of elevated serum TSH levels. Further studies are required to confirm possible effects of occupational exposure to radiation on thyroid function.