[Clinical study of lung cancer complicated by pneumoconiosis]

To elucidate the characteristics of lung cancer complicated by pneumoconiosis, we compared the clinical features of complicated and uncomplicated lung cancer cases. The average age at onset was higher for patients with pneumoconiosis than for those without. Because pneumoconiosis presents various respiratory symptoms, subjective symptoms were less important than objective symptoms in detecting lung cancer complicated by pneumoconiosis. Although fiberoptic bronchoscopy was the predominant diagnostic method, it could not be used with the pneumoconiosis patients. Diagnoses of lung cancer complicated by pneumoconiosis were made more after by percutaneous needle aspiration cytology. Squamous cell carcinoma is the most frequent form of cancer in patients with pneumoconiosis, which suggests that the inhalation of carcinogens may play a role in the pathogenesis of lung cancer. With respect to the smoking index (SI), histological specimens indicated that the incidence of squamous cell carcinoma in patients with pneumoconiosis was significantly higher in heavy smokers (SI > or = 600) than in light smokers (SI < 600) or nonsmokers. It is suspected that smoking affects carcinogenesis of pneumoconiosis. No differences in the distribution of lung cancer (right-left, hilar-peripheral) distinguished the 2 groups. Many of the patients with peripheral-type lung cancer and pneumoconiosis had tumors in the lower lung lobes. These findings underline the importance of encouraging pneumoconiosis patients to avoid lung cancer by not smoking, and to have lung cancer detected in its early stages by undergoing regular medical exams.