Paraneoplastic Syndromes

Key Features

• Small cell lung cancer is most common tumor association

• Can occur despite relatively limited neoplastic growth

• May provide an early clue to presence of certain types of cancer

• Course usually parallels course of the cancer

  • Effective cancer treatment should be accompanied by resolution of the syndrome

  • Conversely, recurrence of the cancer is sometimes heralded by return of syndrome

• Metabolic or toxic effects of the syndrome (eg, hypercalcemia, hyponatremia) may be a more urgent hazard to life than the underlying cancer

• Many of the neuromuscular, dermatologic and rheumatologic paraneoplastic syndromes are caused by antibodies directed against tumor antigens that share epitopes with normal tissue; testing for antibodies can often detect syndrome-specific antibodies

Clinical Findings

• Hypercalcemia, hyponatremia

• Clinical manifestations of cancer are usually due to

  • Pressure effects of local tumor growth

  • Infiltration or metastatic deposition of tumor cells in a variety of organs in the body

  • Certain systemic symptoms

• Patients with advanced or widespread metastatic cancer may have anorexia, malaise, weight loss, and sometimes fever

• Systemic symptoms of cancer are usually not specific (except in the case of functioning tumors)

• In the paraneoplastic syndromes, clinical findings may resemble those of primary endocrine, dermatologic, rheumatologic, hematologic, or neuromuscular disorders

Diagnosis

• See eTable 39–1