Thyroid Cancer, Medullary

• • Aggressive form of thyroid cancer that can be either sporadic or familial

  • Arises from parafollicular or C cells

Epidemiology

• • 5% of malignant tumors of the thyroid

  • 35% of medullary thyroid cancer (MTC) is familial

  • 65% of MTC is sporadic

  • Peak incidence of familial MTC is second to third decade of life

  • Peak incidence of sporadic MTC is fifth to sixth decade of life

Symptoms and Signs

• • Hard thyroid nodule

  • Enlarged or hard cervical lymph nodes

  • Pain in the thyroid or paralaryngeal area

  • Hoarseness

  • Dyspnea

  • Stridor

  • Dysphagia

  • Diarrhea

Laboratory Findings

• • Normal thyroid-stimulating hormone (TSH) levels

  • Elevated calcitonin level (basal or calcium/pentagastrin stimulated)

Imaging Findings

• • US: Demonstrates extent of tumor and can detect enlarged lymph nodes

  • Plain films of neck may reveal irregular dense calcifications of the MTC lesion

• • Tumors contain amyloid

  • Not radioiodine sensitive (not follicular cell-derived)

  • Growth not stimulated by TSH

  • Spread is lymphatic

  • Familial tumors are often multifocal and bilateral (vs unilateral in sporadic disease)

Rule Out

• • Multiple endocrine neoplasia type 2A or 2B

• • Complete history and physical exam, with special consideration to family history and exam of the neck and cervical lymph nodes

  • Fine-needle aspiration biopsy

  • Serum calcitonin

  • Screen for Ret mutations (10% of patients without a family history have de novo mutations)

  • Cervical ultrasound to assess thyroid and regional lymph nodes

• • Prophylactic total thyroidectomy before age 5 recommended for patients without symptoms and if detected by family genetic screening

  • Surgical treatment represents the only chance for cure

  • Nonresectable recurrence of MTC may respond to external beam radiation or multidrug chemotherapy regimen

Surgery

Indications

• • All MTCs should be removed, with central neck dissection, as completely as possible

Medications

• • Postoperative thyroid hormone replacement

Treatment Monitoring

• • Calcitonin level and neck palpation every 3-6 months

Complications

• • Neck hematoma

  • Superior laryngeal nerve injury

  • Recurrent laryngeal nerve injury

  • Transient or permanent hypoparathyroidism

Prognosis

• • Outcome correlates directly with completeness of tumor resection and degree of extrathyroidal spread

  • 10-year survival about 30-40%

References