Parathyroid cancer

Epidemiology

• One of the rarest human cancers - 11 per 10,000,000 per year
• <1% of all patients with primary HPT
• Can occur in patients with familial HPT
• Median age 57yo
• Men and women equally

Pathophysiology

• Almost uniformly functional
• Mostly >3cm in size when excised

Presentation

• Generally severe primary HPT
• 50% have a palpable neck mass
• Often have RLN palsy
• Often calcium >3.49mmol/L, PTH 3-10x normal, increased ALP

Operative findings

• Solid firm mass with a grayish white appearance and a firm consistency
• Normal tissue planes between parathyroid and thyroid are absent
• Invasion of thyroid or straps
• Cervical lymph node mets are uncommon (3%)

Management

• Medical
  • Manage the hypercalcaemia prior to OT if severe
  • Radioresistant and chemotherapy is ineffective
  • Bisphosphonate or cinacalcet to control hypercalcaemia long-term
• Surgical
  • En bloc resection of the cancer and any adjacent involved structures
    • If RLN resected, consider reconstruction with ansa cervicales graft
    • May need to resect trachea/oesophagus
  • Cervical lymph node dissection only if actual metastases are suspected or seen

Prognosis

• Recurrence rates 40-70% within 2-5 years
• Most commonly metastasises to lung and bone
• Disease specific survival median 75 months