Asbestos-Related Lung Cancer

Asbestos related lung cancer is primary lung carcinoma caused or contributed to by asbestos exposure. It occurs with or without asbestosis, and risk rises with cumulative dose.

Epidemiology. All fibre types increase risk, with amphiboles more potent than chrysotile. Risk is greatest in smokers, in whom asbestos and tobacco effects combine multiplicatively or close to it.

Latency. Usually 10 to 30 years or more after first exposure.

Attribution. Causation is accepted when exposure is substantial; a doubling of risk and radiographic or pathological asbestosis are commonly used markers. Exposure thresholds vary between jurisdictions.

Histology. All types occur; adenocarcinoma and squamous cell carcinoma are most frequent.

Pathophysiology.

Fibres cause chronic inflammation, reactive oxygen and nitrogen species generation and DNA damage. Fibre associated macrophage activation and cytokine release promote epithelial transformation.

Asbestos also carries carcinogenic contaminants and absorbs tobacco carcinogens on its surface, contributing to the synergy with smoking.

• New or changed cough, dyspnoea, haemoptysis, chest pain, weight loss and recurrent chest infection.
• Hoarseness, superior vena cava obstruction, bone pain, neurological features and paraneoplastic syndromes in advanced disease.
• Underlying asbestosis or pleural disease may mask symptoms.

Red flags.

• Haemoptysis, stridor, superior vena cava obstruction, spinal cord compression.
• Hypercalcaemia or hyponatraemia.
• Rapid weight loss or new neurological signs.

• Contrast CT chest and upper abdomen.
• Tissue diagnosis by bronchoscopy, image directed biopsy or endobronchial ultrasound, with histology and molecular and PD-L1 testing.
• Staging: PET-CT, brain imaging, mediastinal sampling as needed.
• Lung function with DLCO and exercise testing for surgical fitness. Predicted post-operative FEV1 and DLCO over 60% indicate low risk; 30 to 60% needs exercise testing; under 30% indicates high risk.

Differential diagnosis. Mesothelioma, metastasis, folded lung, benign nodules, tuberculosis, organising pneumonia, lymphoma.

• Multidisciplinary stage directed treatment: surgery, stereotactic radiotherapy, chemoradiotherapy, or systemic therapy chosen by histology and molecular profile. Palliative care involvement in advanced disease.
• Smoking cessation: varenicline orally, 0.5 mg once daily on days 1 to 3, 0.5 mg twice daily on days 4 to 7, then 1 mg twice daily for 12 weeks (a further 12 weeks if abstinent). Maximum 2 mg daily. Monitor neuropsychiatric symptoms, nausea and sleep disturbance. If creatinine clearance is under 30 mL/min, start 0.5 mg once daily and limit to 0.5 mg twice daily.
• Influenza and pneumococcal vaccination; pulmonary rehabilitation.
• Low dose CT screening for eligible people by age and smoking history, where programmes exist.

Monitoring. Response imaging and symptom review directed by treatment; lung function before and after surgery or thoracic radiotherapy.

Referral and escalation. Urgent lung cancer service referral for suspected malignancy; occupational notification and compensation where required.

Special groups. Underlying asbestosis or pleural thickening limits surgical and radiotherapy options and raises the risk of post-treatment respiratory failure.