A Physicians' Guide to
Thyroid Cancer from A-Z

Thyroid Cancer Risk Factors, Symptoms and Signs

Most risk factors for thyroid cancer cannot be controlled by the patient—such as gender, age, and family history. Sometimes information about one or both biological parents is unavailable. Irradiation is an important risk, especially in people exposed during youth. Decades ago, x-ray irradiation of disorders of the head and neck was considered a "safe" medical practice. It was administered to treat facial acne and ringworm (on the scalp).1 Even today people are exposed knowingly or unknowingly to carcinogens in their homes, the workplace, and other environs.

Gender

  • Thyroid cancers affect women 3 times more often than men.2

Age

  • Women are usually diagnosed between the ages of 40 and 50.2,3
  • Men are typically diagnosed between the ages of 60 and 70.2

Diet

  • A higher incidence of papillary thyroid carcinoma is found in regions around the world with high dietary iodine intake (eg, Iceland).1
  • The incidence for follicular adenocarcinoma is higher in iodine-deficient countries.1

Radiation

  • Exposure to 131I from nuclear fallout (eg, Chernobyl) especially when exposure happens prior to 12 years of age.3,4

Genetics

  • Family history of thyroid cancer; especially medullary thyroid cancer.
  • Personal or family history of familial medullary thyroid carcinoma, multiple endocrine neoplasia type 2 (MEN II—subtypes MEN IIA and MEN IIB). All 3 are caused by mutations in the RET proto-oncogene, which encodes molecules that mediate cell adhesion and normal cell development.5
  • Cowden's syndrome (CS) is caused by mutations in the phosphatase and tensin homolog (PTEN)—an enzyme that acts as a tumor suppressor by regulating cell growth and division. CS increases the risk for papillary and/or follicular thyroid cancers.6
  • Familial adenomatous polyposis (FAP) is linked to the APC gene (adenomatous polyposis coli), a gene mutation that increases a person's risk of developing polyps, benign tumors, and cancer.6 FAP is associated with different types of cancer (eg, colorectal, pediatric liver, brain, papillary thyroid). Two retrospective studies (chart reviews) revealed a higher prevalence of thyroid cancer than some previous reports. In one study, 51 patients were clinically and/or genetically diagnosed with FAP.  Six of those patients (female, 12%) were diagnosed with papillary thyroid cancer.7 The second study identified 66 patients with FAP; 4 (6.1%) of them (all female) had a history of thyroid cancer and 3 of the 4 were papillary thyroid cancer.8

Thyroid Cancer Symptoms and Signs

Thyroid carcinoma patients are generally asymptomatic. Symptoms may present in cases of advanced thyroid cancer.

  • Symptoms related to the primary tumor:
    • Visible and/or palpable thyroid nodule(s)
    • Unilateral, bilateral and/or midline neck mass(es) (Fig. 1)
    • New onset of dysphonia (hoarseness, voice impairment)
    • Dyspnea (difficulty breathing)
    • Stridor (noisy breathing such as wheezing)
    • Dysphagia (difficulty swallowing, unable to swallow)
    • Neck pain and/or pressure
    • Cough unrelated to a respiratory problem (eg, cold, asthma)
  • Symptoms related to metastases:
    • Cough with bloody expectoration
    • Bone pain
    • Neurological symptoms (eg, headache, weakness, tingling, seizure)
  • Signs of thyroid cancer include:
    • One or more hard, fixed mass(es) in a thyroid lobe
    • Rapid growth of existing neck mass(es)
    • Cervical lymphadenopathy
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Thyroid Cancer Screening
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