OncologyTier 2Disease (DEADMAN)

Paraneoplastic syndromes

Description

Paraneoplastic syndromes are remote effects of malignancy not directly caused by tumour bulk, invasion, or metastasis - mediated instead by tumour-secreted substances or an immune response cross-reacting with normal tissue

Epidemiology

Can be the presenting feature of an otherwise occult malignancy, sometimes preceding the cancer diagnosis by months - recognising the syndrome should prompt a search for the underlying tumour

Aetiopathogenesis

Hormonal/humoral - ectopic hormone secretion by tumour cells (see hormone-secreting tumours - ACTH, ADH, PTHrP)
Immune-mediated/autoimmune - the tumour expresses an antigen that also occurs on normal tissue (especially neurons), triggering an immune response that cross-reacts with that normal tissue - the mechanism behind most neurological paraneoplastic syndromes

Diagnosis

Syndrome	Classic tumour association
Lambert-Eaton myasthenic syndrome	Small cell lung cancer
Limbic encephalitis / anti-Hu, anti-Ma2	Small cell lung cancer, testicular cancer
Cerebellar degeneration (anti-Yo)	Ovarian, breast cancer
Hypercalcaemia of malignancy (PTHrP)	Squamous cell carcinomas (lung, head/neck), renal cell
Dermatomyositis	Increased malignancy risk across multiple solid tumours, especially in older-onset disease
Trousseau syndrome (migratory thrombophlebitis)	Pancreatic and other adenocarcinomas

Management

Treating the underlying malignancy is the primary treatment for most paraneoplastic syndromes - the syndrome often improves or resolves with successful cancer treatment
Neurological (antibody-mediated) paraneoplastic syndromes may also need specific immunotherapy (as for autoimmune encephalitis) alongside tumour treatment, particularly when antibody-mediated damage is ongoing

Associations

Small cell lung cancer (the most prolific paraneoplastic-associated tumour), hypercalcaemia of malignancy, Lambert-Eaton myasthenic syndrome, dermatomyositis as a malignancy marker

Natural history & complications

New-onset dermatomyositis, especially in an older adult, or an unexplained neurological syndrome with characteristic antibodies, should prompt a thorough age-appropriate malignancy screen even without other cancer symptoms

6 more sections, plus exam facts

Premium unlocks every note across every specialty, and the full exam fact library behind it.

Get premium access