Lung asbestos content in lungs resected for primary lung cancer

The majority of Australia's burden of lung cancer occurs in current or former tobacco smokers. To determine the possible contribution of asbestos exposure in Australians presenting with primary lung cancer, we measured lung asbestos content in cases resected consecutively at a single cardio-thoracic hospital.

Asbestos bodies were quantified by lung tissue digestion, filtration, and light microscopy, and were correlated with exposure questionnaires and clinicopathological features.

We demonstrate high intrarater reproducibility and interrater reliability using these methods. In 463 patients with resected primary lung cancers, asbestos content ranged from 0 to 749 asbestos bodies per gram wet weight (AB/gww). Forty-eight percent of patients had no asbestos bodies identified. One-third had less than or equal to 20 AB/gww (a level previously found to be consistent with urban dwelling). Nineteen percent had lung content in excess of this level. Only 20 cases had AB >100/gww, approximately equivalent to the Helsinki threshold for attribution of lung cancer to asbestos. Median asbestos body counts were higher in patients who reported previous asbestos exposure than in those who reported no exposure. A subgroup of cases gave detailed exposure histories that did not predict presence or absence of asbestos bodies in men or women. In cases with cumulative tobacco exposure less than 20 pack-years, asbestos body counts exceeding 20 AB/gww were overrepresented.

We found that the majority of patients with primary lung cancer at a single Australian center have detectable asbestos in resected lung tissue, but fiber burdens are generally low. The contributory role of this low-level asbestos exposure in causing lung cancer remains uncertain.