Role of occupational asbestos exposure in Hungarian lung cancer patients

What is the frequency of occupational asbestos exposure among patients suffering from malignant respiratory tumours and how many of these tumours are associated with asbestos in Hungary? An internationally established questionnaire with 29 questions, covering the most characteristic activities of asbestos exposure at the workplace was completed for 300 patients with respiratory malignancies, i.e. 297 patients with lung cancer and three with mesothelioma of the pleura. From the questionnaire, the smoking habits were estimated and cumulative asbestos exposure was assessed in fibre-years. Additionally, lung X-rays were classified and the national data on the incidence of malignant pleura mesothelioma were analysed. A cumulative asbestos exposure of 25 fibre-years or more was detected in 11 patients with lung cancer (4%) and in each of the three patients with pleural mesothelioma (100%). In a further 72 patients (24%), cumulative occupational asbestos exposure was assessed as below 25 fibre-years (between 0.01 and 23.9 fibre-years). In this group, car and truck mechanics, and installation and construction workers using asbestos-cement were registered. Among patients with an asbestos exposure of 25 fibre-years or more, six asbestos-cement production workers were observed, among them the three mesothelioma cases. A weak but significant association between positive X-ray findings and exposure estimates could be demonstrated. Additionally, results of the lung tissue fibre counts by scanning transmission electron microscopy were available for 25 of the lung cancer patients. A good correlation was observed between the asbestos fibre counts and the assessment of cumulative asbestos exposure. In Hungary, 84 cases of pleural mesothelioma were registered in 1997 and 73 in 1998. These numbers correspond to an annual incidence of about one new case per 100,000 inhabitants older than 15 years. The annual incidence of lung cancer in Hungary is about 6,000. Since in our series of lung cancer patients about 4% were observed, which could be accepted as representing occupational disease because of a cumulative exposure to 25 fibre-years or more, the annual asbestos related lung tumour incidences may be estimated to be approximately 150 or more. The proportion of nearly two estimated cases of lung cancer per case of pleural mesothelioma corresponds to international experience. Up to now, lung cancer cases only exceptionally have been registered as occupational diseases, i.e. the