Which paraneoplastic syndromes are most commonly associated with lung cancer, and how should they be managed in primary care?

Common paraneoplastic syndromes associated with lung cancer include:

• Hypercalcaemia, often linked to squamous cell carcinoma of the lung.
• SIADH (Syndrome of Inappropriate Antidiuretic Hormone secretion), commonly seen in small-cell lung cancer.
• Cushing's syndrome due to ectopic ACTH production, also associated with small-cell lung cancer.
• Neurological syndromes such as Lambert-Eaton myasthenic syndrome.

Recommended management in primary care involves:

• Early recognition of symptoms suggestive of paraneoplastic syndromes and prompt referral to secondary care for diagnosis and management.
• Supportive care including symptom control and monitoring of biochemical abnormalities (e.g., calcium levels, sodium levels).
• Coordination with oncology and multidisciplinary teams for comprehensive cancer treatment and management of paraneoplastic manifestations.
• Smoking cessation advice and support, as smoking is a major risk factor for lung cancer and may worsen outcomes.

Primary care's role is mainly supportive and involves timely referral and coordination of care rather than direct treatment of paraneoplastic syndromes, which require specialist input NICE NG122.