Asbestos and the lungs- myths and truths Dr Malcolm Ogborne MBBS FRACP

Summary O Asbestos fibers- general O Asbestos-related pleural disease (ARPD)  Pleural plaques  Pleural effusions  Round atelectasis O Asbestosis

O Bronchogenic carcinoma (lung cancer) O Mesothelioma

Asbestos fibers- general O Mined by the ancient Greeks O Used extensively in manufacture world-wide

up until late 20th century O Fire resistant, electrically insulating, tensile strength, sound absorbtion, versatile, cheap. O Plaster, vinyl floors, roofing, acoustic ceilings, fireproofing and heat insulation, electrical insulation, brake pads, gaskits, chemical filters, stage curtains, shoes etc etc

Asbestos fibers- general O Serpentine fibers (curly)  Chrysotile: 90% of world-wide manufacture,

most versatile O Amphibole (needle-like)  Amosite (brown): South Africa  Crocidolite (blue): Wittenoom, southern Africa, Bolivia  Tremolite: India, Turkey, Greece

Chrysotile Asbestos

Crocidolite Asbestos

Asbestos fibers- general O Pliny the Younger 61-114 AD noted ill health

amongst asbestos workers O Asbestos-related dust diseases scientifically described since 1920s  UK Parliamentary report 1930 led to regulation of industry to reduce exposure 1932, US 1942 O Dr J Wagner 1960 recognised the association between asbestos and mesothelioma Wagner Br J Int. Med, 1960, 17;260-71

O Mining ceased in Australia 1983, gradual

phasing out of materials from 1989. Total ban since 2003

Asbestos fibers- general O Fibers deposited in respiratory bronchioles and

alveolar interstitium Chang Am J Pathol 1988, 131:156

O Mucociliary clearence the main defence  Smoking significantly impairs mucociliary

defences O Attacked by MØ, type 1 pneumocytes Brody Am Rev Resp Dis 1981;123:672

O Inflammatory response, formation of asbestos

bodies, attempted removal to pleura.

ARDP- Pleural Plaques O 50% of all exposed patients O Parietal pleural adjacent to the ribs, bilateral  less in intercostal spaces

 absent at apicies, costophrenic angle  Tip of dome of diaphragm pathognomic O Calcified in 50% on CT (80% at biopsy)

O Usually benign process, monitoring not

required  may cause lung restriction with normal DLCO

ARPD- Pleural Plaques

ARPD- Pleural plaques

ARPD- Pleural plaques

ARPD- Benign Asbestosrelated Pleural Effusions O Occur most commonly 1-15 years after the

onset of exposure, but have been reported up to 50y Epler, JAMA 1982, 247:617

O  O 

Small, unilateral Patient usually asymptomatic Serous, serosanguinous, bloody >1/3 have high EØ count (up to 50%) Mattson, Scand Resp Dis 1975, 56:263

O Resolve over several weeks  May leave pleural thickening/ blunting of angle O Main DD is mesothelioma- associated effusion

ARPD- Round Atelectasis O Can occur with any pleural inflammation,

particularly prevalent in ARPD

Mintzer, Chest 1982; 81:457

O Progressive tethering of adjacent lung in a

O 

 

pincer-like process gradually forms a ball of scarred lung Main DD is a metastatic malignant deposit but: Often unilateral Associated pleural plaque disease PET scan or biopsy only occasionally needed

ARDP- Round atelectasis

ARPD- Round atelectasis

ARPD- Round atelectasis

Asbestosis O Pulmonary fibrosis caused by asbestos exposure  Appropriate history of exposure and/or

radiographic evidence (pleural plaques)  Latency 20-30 years Mossman, N Engl J Med 1989; 320: 1721

 Evidence of interstitial fibrosis: HRCT/ biopsy  Absence of other potential causes O Insidious onset, slowly progressive  Main symptom shortness of breath, cough late  No chest pain, wheeze, sputum

Asbestosis O “Usual Interstitial Pneumonia” (UIP) pattern both

radiologically and at biopsy O HRCT (30% may have normal CXR)

Gamau AJR Am J Roenten 1995; 164: 65

   

Predominantly basal and dorsal fibrosis Subpleural microcystic change (honeycombing) Subpleural linear densities Coarse parenchymal bands 2-5cm, often contiguous with the pleura Aberle Clin Chest Med 1991; 12:115

O Gallium scan, BAL for asbestos bodies of limited

use

Asbestosis

Asbestosis

Asbestosis

Asbestosis O Treatment mainly supportive  Smoking cessation  Prevent further exposure  Influenza and pneumococcal vaccinations  Prompt treatment of infection  Oxygen

 ?newer anti-fibrotics- watch this space

Bronchogenic (Lung) Cancer O All fiber types now accepted as an independent

risk for lung cancer  Exposure without smoking 6x RR  Smoking without exposure 11x RR  Exposure and smoking >20 pack years 59x RR Hammond Ann NY Acad Sci 1979; 330: 473

O ?screening CT if smoker and pleural plaques/

clear exposure O Other: laryngeal, renal, oesophagus, biliary Selikoff Environ Health Perspect 1990; 88: 269

Mesothelioma O Pleural carcinoma for which asbestos exposure is the

only clearly established risk  ?Ionising radiation

Tward, Cancer 2006; 07:108 Teta, Cancer 2007; 109: 1432

O Estimated lifetime risk for an asbestos worker

approximately 10%

Selikoff Cancer 1980; 48: 2736

 Risk is proportional to magnitude of exposure  Type of fiber (crocidolite> chrysotile)  Genetic: BAP-1 (histone transcription factor), other Carbone J Trans Med 2012; 10: 179

 ?viral: SV40- not clear Cistaudo Cancer Res 2006; 66: 3049 De Rienzo J Cell Biochem 2002, 84: 455

Mesothelioma O Commonest presentation is an unexplained    

unilateral pleural effusion latency 30-40y, not