Background: Paraneoplastic neurological syndromes (PNS) almost invariably precede detection of the malignancy. Screening for tumours is important in PNS as the tumour directly affects prognosis, and treatment and should be performed as soon as possible.

Objectives: An overview of the screening of tumours related to classical PNS is given. Small cell lung cancer, thymoma, breast cancer, ovarian carcinoma and teratoma, and testicular tumours are described in relation to paraneoplastic limbic encephalitis, subacute sensory neuronopathy, subacute autonomic neuropathy, paraneoplastic cerebellar degeneration, paraneoplastic opsoclonus-myoclonus, Lambert-Eaton myasthenic syndrome, myasthenia gravis and paraneoplastic peripheral nerve hyperexcitability.

Methods: Many studies with class IV evidence were available; one study reached level III evidence. No evidence-based recommendations for Levels A–C were possible, but good practice points were agreed by consensus.

Recommendations: The nature of the antibody, and to a lesser extent the clinical syndrome, determines the risk and type of an underlying malignancy. For screening of the thoracic region a CT thorax is recommended, which if negative is followed by FDG-PET. Breast cancer is screened for by mammography, followed by MRI. For the pelvic region ultrasound is the investigation of first choice followed by CT. Dermatomyositis patients should have CT thorax/abdomen, ultrasound (US) of the pelvic region and mammography in women, US of testes in men under 50 years and colonoscopy in men and women over 50. If primary screening is negative, repeat screening after 3–6 months and screen every 6 months for up to 4 years. In LEMS, screening for 2 years is sufficient. In syndromes where only a subgroup of patients has a malignancy, tumour markers have additional value to predict a probable malignancy.