No abstract

Cytologic examinations of sputum collected periodically since 1957 on a group of uranium miners have been studied and related to the development of bronchogenic carcinoma. Many individuals developed abnormal squamous cell metaplasia that gradually progressed, in several, to develop invasive carcinoma. This progression has been classified into mild, moderate, and marked atypical, squamous cell metaplasias and carcinoma in situ. Cigarette smoking and uranium mining were both associated with the prevalence of these atypias, and with carcinoma in situ and invasive cancer. Neither of these agents, however, appeared to be strongly associated with the duration of the stages of atypia. Age at start of uranium mining was more strongly associated with age at development of carcinoma in situ than other factors tested. There appears to be an average period of 4 or 5 years during which individuals exfoliate cells that are markedly atypical or represent carcinoma in situ in their sputum before developing invasive carcinoma of epidermoid or small cell, undifferentiated varieties. Periodic sputum surveillance of groups at elevated risk of bronchogenic cancer can utilize this period for early detection and treatment.

A comprehensive autopsy survey of the large bowel showed that adenomas were very common lesions occurring in about one-half of the 518 cases studied. The great majority were small adenomatous polyps (tubular adenomas), 86.7% measuring less than 10 mm in diameter. Adenomas with a more complex tubulovillous pattern were larger with a mean diameter of 19.0 mm. There was no apparent incresae in mean size of adenomas with age. Nineteen clinically unsuspected cancers were discovered. Fourteen (8 in situ and 6 invasive) cancers had areas of residual benign adenoma. Five invasive cancers had no residual benign component. No in situ carcinomas or small (less than 10 mm) invasive cancers not containing residual adenoma were found. The results suggest that, although adenomas of the large bowel are very common, the vast majority are simple adenomatous polyps which do not undergo progressive growth and malignant change. Conversely, it appears that cancers may arise from benign adenomas which have the characteristics of large size and a more complex villous architecture.