Hereditary Cancer Risk Assessment Basics

The goal of most hereditary cancer programs is to provide individual risk assessment that can be incorporated into the patient’s ongoing medical care. The programs usually evaluates families with multiple members with cancer (of the same or different type) for the purpose of assessing the likelihood of a hereditary cancer syndrome. Patients are usually referred by their physician based upon their personal medical and/or family histories.

Often several sessions are required. The initial session includes a review of the patient’s medical history as well as three generational family history. The counselor will review this information within the context of risk for a hereditary cancer syndrome. The benefits, risks and limitations of testing will be described in detail. Often testing options can be offered at an initial visit. However, sometimes it is necessary to collect medical records on affected family members in order to understand the risk that exists for the patient and family. 

Genetic testing will then be offered if appropriate. If the patient decides to proceed with testing a final appointment is scheduled to review the results in person. This visit includes interpretation of the results a discussion of how this information affects medical management and the impact on the extended family. 

Some important factors that would indicate this type of evaluation include:

• Cancer that developed at an early age, usually less than 50.
• Individuals with rare cancer i.e. male breast cancer.
• More than one primary cancer in an affected individual.
• Other physical signs such as colon polyps, moles, desmoids tumors, thyroid nodules, and fatty tumors.
• Different cancers in a family that are known to be genetically related such as breast and ovarian cancers.
• Several generations in the family affected by cancer.
• Clustering of cancers that are known to be genetically related (such as breast and ovarian, colon and uterine and breast and thyroid).
• Breast or ovarian cancer and Ashkenazi (eastern European) Jewish ancestry.
• An identified genetic mutation in the family.
• Known cancer syndrome in the family (for example Lynch syndrome, Cowden syndrome, MEN and others).

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Staging and risk stratification of thyroid cancer improved with SPECT/CT

The use of single positron emission computed tomography (SPECT)/computed tomography (CT) has been reported to change clinical management in a significant number of thyroid cancer patients according to research presented in the May issue of The Journal of Nuclear Medicine. Information obtained from these scans not only helps determine the need for radioiodine therapy or alterative options, but also impacts the long-term follow-up strategy.

"In this article I aimed to highlight the role of radioiodine imaging in risk stratification of patients with thyroid cancer and to assess the contribution it brings to the completion of staging and the decision to omit or proceed with I-131 therapy," said Anca M. Avram, MD, author of "Radioiodine Scintigraphy with SPECT/CT: An Important Diagnostic Tool for Thyroid Cancer Staging and Risk Stratification." She continued, "The new technology of SPECT/CT has substantially improved the interpretation of planar studies and can be implemented in the post-operative management protocols of thyroid cancer patients."

SPECT/CT has commonly been used for imaging thyroid cancer patients after radioiodine therapy, with the advantages of substantially reducing the number of equivocal foci seen on planar imaging alone, determining lymph nodal status more accurately than planar imaging and improving anatomical localization of activity foci seen on planar imaging. Studies cited in the article report on the high diagnostic value of radioiodine SPECT/CT, resulting in changes in risk stratification and clinical management in a substantial number of patients (ranging between 25 – 47 percent of patients).

More recently, SPECT/CT has been utilized prior to radioiodine therapy to better identify and characterize focal activity seen on planar scans for differentiating between metastatic lesions and benign uptake in residual thyroid tissue or normal organs. Information acquired with pre-ablation SPECT/CT scans can be used in addition to histopathology information to complete staging and risk stratification prior to radioablation. The pre-ablation scans can reveal unsuspected regional and distant metastatic lesions, resulting in changes in the prescribed I-131 activity, either by adjusting empiric I-131 doses or performing dosimetry calculations.

The article reports that SPECT/CT changed post-surgical staging in 21 percent patients, modified the treatment approach in 36 percent patient with disease, and led to avoidance of unnecessary I-131 therapy in 20 percent patients without disease. The findings on pre-ablation scans altered the recommended I-131 therapy in 58 percent patients as compared to therapy based on histopathologic risk stratification alone, by appropriately prescribing higher activities for treatment of regional and distant metastases and minimizing the activity prescribed for thyroid remnant ablation.

SPECT/CT is also very useful for evaluating unusual radioactivity distributions in thyroid cancer patients; accurate anatomic localization of radioactivity foci permits rapid exclusion of physiologic mimics of disease, or confirmation of metastatic lesions to unexpected sites.

"Diagnostic radioiodine scintigraphy with SPECT/CT provides a clear advantage for the management of patients with thyroid cancer," said Avram. "By integrating clinical, pathology and imaging information, the nuclear medicine physicians are able to offer an individualized treatment plan, bringing the nuclear medicine community a step closer to the goal of personalized medicine."

The incidence of thyroid cancer has increased 2.4 times since 1975. The U.S. National Cancer Institute estimates that in 2012 more than 56,000 cases of thyroid cancer will be diagnosed and nearly 1,800 individuals will die from the disease.

Source: Society of Nuclear Medicine

Diagnosing Thyroid Cancer: Radionuclide Scanning Of The Thyroid

Thyroid Radionuclide Scanning

• This test is performed by a nuclear medicine specialist. After a small, safe amount of radioisotope (I-123 or Tc99) is taken by mouth or injected into a vein, the radiologist obtains pictures of the thyroid.
  
• Nodules can be seen as dark spots (called "cold") or bright spots (called "hot").
  
• Nodules that concentrate the radioisotope are "hot" and are usually making excessive thyroid hormone. "Hot" nodules are rarely associated with cancer and may not require FNAB investigation.
  
• Nodules that do not concentrate iodine are "cold" and are usually making less than normal amounts of thyroid hormone
   
  • More than 80%-85% of all thyroid nodules are "cold".
    
  • These nodules are typically more worrisome for cancer, and require evaluation with FNAB.

Diagnosing Benign Thyroid Nodules vs. Thyroid Cancer

FINE NEEDLE ASPIRATION BIOPSY (FNAB)

A biopsy is the only way to tell if a thyroid nodule is cancerous. But cancer may be more likely if you have:

• A single, hard lump that feels very different from the rest of the thyroid tissue or other thyroid nodules.
• A nodule that keeps growing for weeks or months.
• A nodule that does not move when you touch it.
• Swollen lymph nodes in your neck.
• A hoarse or scratchy voice that does not go away.

Some other conditions that cause similar symptoms include hyperthyroidism and thyroiditis.

• If a thyroid nodule is larger than 1 cm, or it has other worrisome characteristics seen on ultrasound or other imaging tests, then a FNAB may be performed.
  
  
• This office procedure does not require anesthesia and consists of passing small needles (similar to those used to draw blood from the arm) into the thyroid nodule in the neck. This is a quick and usually painless procedure.
  
  
• This procedure may be done on multiple nodules.
  
  
• Ultrasound guidance may be used to assist in the FNAB of nodules that are bigger than 1-1.5 cm but cannot be felt on physical examination.
  
  
• A sample of the contents of each nodule (to include fluid, blood, or tissue) are removed in the needle and examined by the pathologist under a microscope.
• Pathologists can identify certain features in the nodule sample.

FNAB results are characterized as one of the following:

• Benign: This is the most common outcome of a FNAB. The typical finding is a nodule filled with colloid protein, a normal component of the thyroid. Benign nodules can be followed over time with serial physical exams or ultrasound exams. Further intervention is only necessary if enlargement occurs or new symptoms develop. 
  
  
• Malignant: Some thyroid cancers can be diagnosed directly from the FNAB results (for example, papillary thyroid cancer). Other thyroid cancers cannot be diagnosed from the FNAB results (such as follicular thyroid cancer) because the diagnosis rests not simply upon the appearance of the tissue within the nodule, but also on the level of the invasion of surround blood vessels and tissue by the nodule. For these nodules, surgical removal of a portion or the entire thyroid is recommended.
  
  
• Indeterminate: This is neither definitively benign nor malignant. Given that the risk for cancer is increased by 20% in such cases, surgical removal of a portion or the entire thyroid is typically recommended. Often, a radionuclide scan will be done to obtain functional information (if the nodule is actively producing thyroid hormones) in order to avoid an unnecessary surgery.
  
  
• Non-diagnostic: This means that there are not enough of the tissue cells present in the sample to make a diagnosis. Non-diagnostic FNABs will typically result in a repeat FNAB or definitive surgery.

Cystic nodules more often result in a non-diagnostic FNAB due to higher fluid content than solid content in the sample obtained from the nodule.

Updated: Thyroid Cancer Staging Guide

The stage of a cancer is a description (usually numbers I to IV with IV having more progression) of the extent the cancer has spread. The stage often takes into account the size of a tumor, how deeply it has penetrated, whether it has invaded adjacent organs, how many lymph nodes it has metastasized to (if any), and whether it has spread to distant organs. Staging of cancer is the most important predictor of survival, and cancer treatment is primarily determined by staging. Thus, staging does not change with progression of the disease as it is used to assess prognosis. 

A patients' cancer, however, may be re-staged after treatment but the staging established at diagnosis is rarely changed. Cancer staging can be divided into a clinical stage and a pathologic stage. In the TNM (Tumor, Node, Metastasis) system, clinical stage and pathologic stage are denoted by a small "c" or "p" before the stage (e.g., cT3N1M0 or pT2N0).

• Clinical stage is based on all of the available information obtained before a surgery to remove the tumor. Thus, it may include information about the tumor obtained by physical examination, radiologic examination, and endoscopy.
• Pathologic stage adds additional information gained by examination of the tumor microscopically by a pathologist.

Because they use different criteria, clinical stage and pathologic stage often differ. Pathologic staging is usually considered the "better" or "truer" stage because it allows direct examination of the tumor and its spread, contrasted with clinical staging which is limited by the fact that the information is obtained by making indirect observations at a tumor which is still in the body. 

However, clinical staging and pathologic staging should complement each other. Not every tumor is treated surgically, therefore pathologic staging is not always available. Also, sometimes surgery is preceded by other treatments such as chemotherapy and radiation therapy which shrink the tumor, so the pathologic stage may underestimate the true stage. This staging system is used for most forms of cancer, except brain tumors and hematological malignancies. 

The American Joint Committee on Cancer (AJCC) created the following staging system for Thyroid Cancer Staging

• T1 - Tumor diameter 2 cm or smaller
• T2 - Primary tumor diameter greater than 2-4 cm
• T3 - Primary tumor diameter greater than 4 cm limited to the thyroid or with minimal extrathyroidal extension
• T4a - Tumor of any size extending beyond the thyroid capsule to invade subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve
• T4b - Tumor invades prevertebral fascia or encases carotid artery or mediastinal vessels
• TX - Primary tumor size unknown, but without extrathyroidal invasion
• NO - No metastatic nodes
• N1a - Metastases to level VI (pretracheal, paratracheal, and prelaryngeal/Delphian lymph nodes)
• N1b - Metastasis to unilateral, bilateral, contralateral cervical, or superior mediastinal mode metastases
• NX - Nodes not assessed at surgery
• MO - No distant metastases
• M1 - Distant metastases
• MX - Distant metastases not assessed

Stage I (any T, any N, M0)

Stage II (any T, any N, M1)


Author: Mark E Gerber, MD, FACS, FAAP  Clinical Assistant Professor of Otolaryngology, University of Chicago, Pritzker School of Medicine; Section Head, Pediatric Otolaryngology-Head and Neck Surgery, NorthShore University HealthSystem  


Co-Author: Brian Kip Reilly, MD  Assistant Professor of Otolaryngology and Pediatrics, Department of Otolaryngology, Children's National Medical Center, George Washington University School of Medicine

Diagnostic Testing for Thyroid Cancer Basics

The Following Diagnostic Tests and Procedures  that examine the thyroid, neck, and blood are used to detect (find) and diagnose thyroid cancer.

• Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or swelling in the neck, voice box, and lymph nodes, and anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.

• Laryngoscopy: A procedure in which the doctor checks the larynx (voice box) with a mirror or with a laryngoscope. A laryngoscope is a thin, tube-like instrument with a light and a lens for viewing. A thyroid tumor may press on vocal cords. The laryngoscopy is done to see if the vocal cords are moving normally.

• Blood hormone studies: A procedure in which a blood sample is checked to measure the amounts of certain hormones released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that makes it. The blood may be checked for abnormal levels of thyroid-stimulating hormone (TSH). TSH is made by the pituitary gland in the brain. It stimulates the release of thyroid hormone and controls how fast follicular thyroid cells grow. The blood may also be checked for high levels of the hormone calcitonin.

• Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances, such as calcium, released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that makes it.

• Radioactive iodine scan (RAI scan): A procedure to find areas in the body where thyroid cancer cells may be dividing quickly. Radioactive iodine (RAI) is used because only thyroid cells take up iodine. A very small amount of RAI is swallowed, travels through the blood, and collects in thyroid tissue and thyroid cancer cells anywhere in the body. Abnormal thyroid cells take up less iodine than normal thyroid tissue. Areas that do not absorb the iodine normally (cold spots) show up lighter in the picture made by the scan. Cold spots can be either benign (not cancer) or malignant, so a biopsy is done to find out if they are cancer.

• Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The picture can be printed to be looked at later. This procedure can show the size of a thyroid tumor and whether it is solid or a fluid-filled cyst. Ultrasound may be used to guide a fine-needle aspiration biopsy.

• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.

• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).

• PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.

• Fine-needle aspiration biopsy of the thyroid: The removal of thyroid tissue using a thin needle. The needle is inserted through the skin into the thyroid. Several tissue samples are removed from different parts of the thyroid. A pathologist views the tissue samples under a microscope to look for cancer cells. Because the type of thyroid cancer can be hard to diagnose, patients should ask to have biopsy samples checked by a pathologist who has experience diagnosing thyroid cancer.

• Surgical biopsy: The removal of the thyroid nodule or one lobe of the thyroid during surgery so the cells and tissues can be viewed under a microscope by a pathologist to check for signs of cancer. Because the type of thyroid cancer can be hard to diagnose, patients should ask to have biopsy samples checked by a pathologist who has experience diagnosing thyroid cancer.

MEDICAL REVIEW: 02/12/2012

What Causes Thyroid Cancer ?

 Although scientists have found that thyroid cancer is linked with a number of other conditions (described in  "What are the risk factors for thyroid cancer?"), the exact cause of most thyroid cancers is not yet known. Researchers have made great progress in understanding how certain changes in a person's DNA can cause thyroid cells to become cancerous. 

• DNA is the chemical in each of our cells that makes up our genes – the instructions for how our cells function. We usually look like our parents because they are the source of our DNA. However, DNA affects more than how we look. It also can influence our risk for developing certain diseases, including some kinds of cancer.

• Some genes contain instructions for controlling when our cells grow and divide. Certain genes that speed up cell division or cause cells to live longer than they should are called oncogenes. Others that slow down cell division or cause cells to die at the appropriate time are called tumor suppressor genes. Cancers can be caused by DNA changes that turn on oncogenes or turn off tumor suppressor genes.

• People inherit 2 copies of each gene – one from each parent. People can inherit damaged DNA from one or both parents, which accounts for inherited cancers. Most cancers, though, are not inherited. In these cases, a person's DNA is damaged by exposure to something in the environment, like smoking or radiation. Other DNA changes may just be random events that sometimes happen inside a cell, without having an external cause.

Papillary Thyroid Cancer:  Several DNA mutations have been found in some forms of papillary thyroid cancer. Many of these cancers have changes in specific parts of the RET gene. The altered form of this gene, known as the PTC oncogene, is found in about 10% to 30% of papillary thyroid cancers overall, and in a larger percentage of these cancers found in children and/or linked with radiation exposure. These RET mutations usually are acquired during a person's lifetime rather than being inherited. They are present only in cancer cells and are not passed on to the patient's children.

• Many (30% to 70%) papillary thyroid cancers contain a mutation of the BRAF gene. The BRAF mutation is less common in thyroid cancers in children and in those thought to arise from exposure to radiation. Cancers with BRAF changes tend to have more aggressive growth and a greater likelihood of spreading to other parts of the body. 

• Both BRAF and RET/PTC changes are thought to cause cells to grow and divide. It is extremely rare for papillary cancers to have changes in both the BRAF and RET/PTC genes. Some doctors now advise testing papillary cancer samples for these gene mutations, as some studies have suggested they may affect a person's prognosis (outlook). 

• Changes to other genes have also been tied to papillary thyroid cancer, including those in the NTRK1 gene and the METgene.

Follicular Thyroid Cancer:  Acquired changes in the RAS oncogene have a role in causing some follicular thyroid cancers.

Anaplastic Thyroid Cancer:  These cancers tend to have some of the mutations described above and often have changes in the p53 tumor suppressor gene and the CTNNB1 oncogene as well.

Medullary Thyroid Cancer:  People who have medullary thyroid carcinoma (MTC) have mutations in different parts of the RET gene compared with papillary carcinoma patients. Nearly all patients with the inherited form of MTC and about 1 of every 10 with the sporadic (non-inherited) form of MTC have a mutation in the RET gene.

• Most patients with sporadic MTC have acquired mutations present only in their cancer cells. Those with familial MTC and MEN 2 inherit the RET mutation from a parent. These mutations are present in every cell of the patient's body and can be detected by testing the DNA of blood cells.

• In people with inherited mutations of RET, one RET gene is usually normal and one is mutated. Because every person has 2RET genes but passes only one of them to a child (the child's other RET gene comes from the other parent), the odds that a person with familial MTC will pass a mutated gene on to a child are 1 in 2 (or 50%).

Last Medical Review: 06/29/2011

Last Revised: 01/20/2012

Diagnosing Pediatric Thyroid Cancer: Biopsy

Fine-needle aspiration biopsy: 

• FNAB is the criterion standard in the diagnostic workup of adult thyroid nodules. Several studies report efficacy in the pediatric population.

• High diagnostic accuracy with experienced pathologists improves the selection of pediatric patients for surgery and is an adjunct to guide further management.

• Ultrasonography can be a useful guide for percutaneous needle biopsy when the lesion is difficult to identify with palpation.

• FNAB is often not practical in children younger than 10 years; therefore, excisional biopsy (surgical removal of nodule or tumor mass) under general anesthesia is recommended in this population.

• Using molecular polymerase chain reaction (PCR) studies on FNAB aspirate is mostly beneficial in the clinical research setting. It can be used in a very small number of patients for diagnostic purposes, but it remains expensive.

Significant Histologic Findings Review

Follicular adenoma is the most common cause of solitary nodules of the thyroid in the pediatric population. Adenomas are solitary, well circumscribed, and well encapsulated and are composed of glandular epithelium. Most are histologically follicular but are occasionally papillary.

• Most thyroid cancers (papillary, follicular, anaplastic) originate from follicular cells. Medullary thyroid cancers (25% hereditary vs 75% sporadic) are of C-cell (calcitonin-producing) origin.

• Thyroid malignancies in children are usually well-differentiated papillary or papillary-follicular subtypes, but all histologic types have been observed. 

• Papillary carcinoma lesions, which comprise an estimated 72% of pediatric thyroid cancers, are irregular, solid, or cystic masses that arise from follicular epithelium.

• Microscopically, pediatric thyroid cancer masses or nodules have fronds of epithelium and distinct uniform cells with rare mitoses. Most contain both papillary and follicular components. The cells contain pink, finely granular cytoplasm with large pale nuclei (Orphan Annie eyes) and nuclear grooves. 

• Psammoma bodies (rounded calcified deposits) can be found in approximately 50% of the lesions. 

• Pediatric Papillary Carcinoma has frequent lymphatic and pulmonary metastases.

• Follicular carcinoma lesions, which comprise 18% of pediatric thyroid cancers, are usually encapsulated and have highly cellular follicles and microfollicles with compact dark-staining nuclei of fairly uniform size, shape, and location. Pathologic diagnosis can be made only when invasion of the capsule, adjacent glands, lymphatics, or blood vessels is seen. 

• Pediatric Follicular Carcinoma metastasizes intravascularly to the lungs, brain, and bones. When a portion of the cells in the tumor are found to be oxyphilic (Hürthle cells), it is called a Hürthle cell tumor. These lesions tend to have a less favorable prognosis.

• MTC or Pediatric Medullary Thyroid Cancer arises from the thyroid parafollicular or C cells, which secrete calcitonin and are derived from the neural crest and ultimobranchial body. Hyperplasia of the C cells is thought to represent a precancerous state. 

• Histologically, MTC is composed of columns of epithelial cells and dense stroma that typically stain for amyloid and collagen. The nuclei are hyperchromatic, and mitoses are common. The cells have a fusiform shape and may form a whirling pattern. Calcifications are observed in 50% of these lesions.

Author: Mark E Gerber, MD, FACS, FAAP  Clinical Assistant Professor of Otolaryngology, University of Chicago, Pritzker School of Medicine; Section Head, Pediatric Otolaryngology-Head and Neck Surgery, NorthShore University HealthSystem  

Co-Author: Brian Kip Reilly, MD  Assistant Professor of Otolaryngology and Pediatrics, Department of Otolaryngology, Children's National Medical Center, George Washington University School of Medicine 

Diagnosing Pediatric Thyroid Cancer: Imaging Studies

Imaging studies reveal the malignant potential and the extent of disease, and they provide an anatomical roadmap for surgical planning. The following are the imaging studies with the highest yield.

Ultrasonography:  The safest and most widely available imaging technique, is the first-line screening diagnostic test in all pediatric patients with thyroid nodules. In particular, children with a history of radiation exposure should be observed with serial ultrasonography. 

• Nodules that enlarge even a few millimeters should undergo FNAB.

• Ultrasonography is useful in differentiating solid nodule or mass from cystic lesions and in revealing nonpalpable lesions. Many investigators consider cystic lesions to be benign lesions that represent hemorrhage into, or degeneration of, an adenomatous nodular goiter.

• A solid nodule is more likely to be malignant; however, up to 50% of malignant lesions may have a cystic component, and approximately 8% of cystic lesions represent malignancies.

• Ultrasonography reveals critical information regarding the risk of benign versus malignant disease. Benign features on ultrasound include multiple, solid isoechogenic or nonechogenic lesions and a uniform peripheral halo. Malignant features include a thick irregular halo.

• Color-Doppler sonography may aid in the diagnosis in patients with hyperfunctioning nodules (hot on scintigraphy and usually benign histologically), indicating an intensive vascular flow within a highly vascularized lesion and no visible flow through the remaining suppressed thyroid gland. Color-Doppler sonography is also valuable in distinguishing a cystic lesion (with no vascular flow) from a solid neoplasm (with intranodular flow).

• One of the most helpful capabilities of ultrasonography is guidance of percutaneous needle biopsy.

Radionucleotide scan (scintigraphy): Thyroid scintigraphy is most useful in revealing tissue function in thyroglossal duct cysts (eg, ensuring that thyroid tissue in the normal location is functioning) and in diagnosing ectopic thyroid. However, thyroid scintigraphy has not proven worthwhile in distinguishing malignant from benign disease.

• Classic hot nodules show uptake only in the nodule area of the thyroid and are associated with about a 6% incidence of malignancy. Harach et al (2002) wrote that untreated hot nodules can progress to carcinoma. 

• Surgical treatment is advisable for all children and adolescents with autonomously functioning thyroid nodules because of the risks of hyperthyroidism and thyroid carcinoma.

• Cold nodules are usually benign adenomas, although, in children, a larger number of them are carcinomas. Solid lesions that are cold on scintigraphy are malignant in about 30% of children.

• Total-body radioactive iodine (RAI) scans often reveal pulmonary nodal metastases, which are missed on radiography.

CT Scans

• Noncontrast CT scans can be helpful in patients with substernal extension, local invasion, or lymph node metastasis. 

• At initial evaluation, approximately 20% of children have pulmonary metastasis that can be revealed by either chest radiography or CT scan.

• Children have a much higher incidence of pulmonary involvement (spread to or metastatic thyroid cancer disease) than adults.

• The CT lung findings, which usually consist of diffuse miliary spots and, less often, infiltrating nodules, are often also best noted with RAI scans.

Author: Mark E Gerber, MD, FACS, FAAP  Clinical Assistant Professor of Otolaryngology, University of Chicago, Pritzker School of Medicine; Section Head, Pediatric Otolaryngology-Head and Neck Surgery, NorthShore University HealthSystem  

Co-Author:  Brian Kip Reilly, MD  Assistant Professor of Otolaryngology and Pediatrics, Department of Otolaryngology, Children's National Medical Center, George Washington University School of Medicine 

Diagnosing Pediatric Thyroid Cancer: Laboratory Studies

• Thyroglossal duct cysts, the most common developmental thyroid anomaly, carry an increased, albeit small, risk of malignant transformation. This is one of the reasons excision with the Sistrunk procedure (removal of cyst, central hyoid bone, and core from the base of the tongue) is recommended. However, only 8 cases of malignant thyroglossal duct transformation have been reported in the literature.

• Levels of serum triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) are usually within reference ranges in malignancy. Therefore, although these blood studies have no predictive value for thyroid cancer, they help shape the differential diagnosis of a child's thyroid mass.

• Antithyroid antibodies are helpful in diagnosing chronic lymphocytic thyroiditis. Thyroglobulin levels may be elevated in differentiated thyroid carcinoma and may help in postoperative monitoring. The thyroglobulin level should not be measured until at least 14 days after fine-needle aspiration (FNA) to prevent an artificial level elevation from the needle instrumentation.

• Traditional screening for both medullary thyroid cancer (MTC) and thyroid C-cell hyperplasia is performed by measuring calcitonin levels before and after pentagastrin stimulation. Screening for multiple endocrine neoplasia 2 (MEN2) is now possible with DNA analysis for specific mutations in the ret protooncogene.

• Serum carcinoembryonic antigen (CEA) should be measured in those in whom MTC is suspected. Unfortunately, a negative value may be found in advanced stages of the disease.

• Obtain a 24-hour urine collection to screen for catecholamines metabolites, as a pheochromocytoma or paraganglioma should be surgically removed before thyroidectomy to avoid a hypertension crisis during surgery.

• Obtain genetic testing at birth in children at risk for MEN2B and no later than age one year in children at risk for MEN2A.

Author: Mark E Gerber, MD, FACS, FAAP  Clinical Assistant Professor of Otolaryngology, University of Chicago, Pritzker School of Medicine; Section Head, Pediatric Otolaryngology-Head and Neck Surgery, NorthShore University HealthSystem  

Co-Author: Brian Kip Reilly, MD  Assistant Professor of Otolaryngology and Pediatrics, Department of Otolaryngology, Children's National Medical Center, George Washington University School of Medicine 

Could it be thyroid cancer? When To Call The Doctor

When To Call a Doctor

Call your doctor if you have any of these signs of thyroid nodules:

• Swelling in your neck for more than 2 weeks
• A hoarse or scratchy voice that is not caused by a cold or throat infection and lasts longer than 1 month
• A hard time swallowing or breathing
• Symptoms of a thyroid problem such as feeling tired, weak, or nervous, losing weight, having trouble sleeping, or having a fast heartbeat

If you have had part of your thyroid gland removed because of noncancerous thyroid nodules, you will need regular medical checkups to make sure your thyroid gland is working well.

Watchful Waiting

For some kinds of health problems, you can wait and see what happens for a while before you and your doctor decide what kind of treatment you should have. This is called watchful waiting.

Because of the small risk of cancer, watchful waiting is not recommended for people with thyroid nodules.

Call your doctor if you have swelling in your neck that does not go away, problems swallowing, a hoarse or scratchy voice that has lasted several weeks, or any other symptoms of a thyroid problem.

Who To See

Different types of health professionals can help treat a thyroid problem.

• Family medicine doctor or general practitioner
• Internist
• Pediatrician
• Your doctor may also refer you to an endocrinologist for further tests and treatment.

If you need a special exam or treatment, you may see one of these types of doctors:

• Nuclear medicine physician (a doctor who specializes in medicine using different types of radioactive substances)
• Surgeon and/or Otolaryngologist (an ear, nose, and throat specialist)