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Poster Sessions
    Friday 19, November, 2004, 12:30-18:30, (16:00-17:00, Q&A) No.3 CR
Saturday 20, November, 2004, 09:30-18:30, (16:00-17:00, Q&A) No.3 CR
  Sunday 21, November, 2004, 09:30-12:30, No.3 CR

Poster Sessions
The Effect on Lung Cancer Risk of Having Asbestosis beyond The Dose Related Effect of Asbestos Alone
Alison Reid1*, Nicholas De Klerk1,2, Gina Ambrosini1, Nola Olsen1, Bill Musk1,3
1School of Population Health, University of Western Australia, Australia
2Institute of Child Health Research, University of Western Australia, Australia
3Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
ABSTRACT:

Background: To determine if the presence of asbestosis is a prerequisite (precursor) for lung cancer in subjects with known asbestos exposure.
Methods: 2214 former workers and residents of Wittenoom, a crocidolite mining and milling town in Western Australia, with known asbestos exposure (duration, intensity and time since first exposure), annual chest x-rays and smoking information, participating in a cancer prevention programme, using Vitamin A (beta carotene for the first five years in half the participants, retinyl palmitate for everyone else). The first x-ray was read for 1988 study participants between 1990 and 1996 to obtain radiographic evidence of asbestosis as per the UICC (ILO) Classification. Cox proportional hazards modelling was performed to assess the association between asbestosis, asbestos exposure and lung cancer.
Findings: Twelve percent of study participants had radiographic evidence of asbestosis on initial x-ray. Smoking status was the strongest predictor of lung cancer with current smokers (OR=31.7 95%CI 4 - 235) having the greatest risk. Radiographic asbestosis (OR=2.15 95%CI 1.21 - 3.82) and asbestos exposure (OR=1.24 95%CI 1.05 E1.45) were significantly associated with an increased risk of lung cancer.
Interpretation: In this cohort of former workers and residents of Wittenoom, asbestosis is not a mandatory precursor for asbestos related lung cancer. These findings support the hypothesis that it is the asbestos fibre per se that causes lung cancer and that this can develop with or without the presence of asbestosis, but that the presence of asbestosis further increases the lung cancer risk: this may be a result of underestimating the exposures.