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Arsenic is a well-documented human carcinogen. Previous studies on urinary bladder and skin cancers have shown that arsenic can cause specific cell types of malignancy. To evaluate whether this is also true for lung cancers, we conducted a study on 243 townships in Taiwan. We identified patients through the National Cancer Registry Program and compared the proportion of each major cell type between an endemic area of arsenic intoxication with exposures through drinking water, which includes 5 of the townships and the other 238 townships. To control for gender and age, we analyzed data on men and women separately and divided patients into four age groups. A total of 37,290 lung cancer patients, including 26,850 men and 10,440 women, was diagnosed between January 1, 1980 and December 31, 1999 in study townships. Patients from the endemic area had higher proportions of squamous cell and small cell carcinomas, but a lower proportion of adenocarcinomas. These findings were similar across all age groups in both genders, although the lack of data on smoking is a limitation of our study. The results suggested that the carcinogenicity of arsenic on lungs is also cell type-specific: squamous cell and small cell carcinomas appeared to be related to arsenic ingestion, but not adenocarcinoma. Whereas data in the literature are limited, the association between adenocarcinoma and arsenic exposures through inhalation appeared to be stronger than that of squamous cell carcinoma. Therefore, we speculate that arsenic may give rise to different mechanisms in the development of lung cancers through different exposure routes.

Since 1994 an endemic of chronic obstructive pulmonary disease (COPD) has developed in Taiwan after a prevalent use of a body-weight-reducing vegetable, Sauropus androgynus (SA). All conventional treatments for COPD, including steroids and bronchodilators, had been ineffective. Studies of limited lung biopsy specimens from these patients revealed bronchiolitis obliterans. A few patients died, but many developed protracted chronic respiratory failure. Because of the chronic debilitation and ineffective conventional treatments, single lung transplants were performed as the last resort in four patients. The excised lungs revealed focal fibromuscular sclerosis and obliteration of bronchial arteries in the wall of large bronchi 4 to 5 mm in diameter with segmental necrosis of bronchi 2 to 4 mm in diameter. Bronchi immediately proximal to the necrotic zone showed fibrosis and atrophy of cartilage, bronchial glands, and smooth muscle cells; bronchioles immediately distal showed obstruction or dilatation. Most bronchi larger than 5 mm, pulmonary vessels, small bronchioles, and alveoli were little altered. The pathologic changes were most consistent with segmental ischemic necrosis of bronchi at the water-shed zone of bronchial and pulmonary circulation. The specific etiologic agent and detail of pathogenesis of this SA-related COPD needs further investigation.