CARCINOMA OF THE LUNG IN OKINAWA, JAPAN - WITH SPECIAL REFERENCE TO SQUAMOUS-CELL CARCINOMA AND SQUAMOUS METAPLASIA

In Okinawa, a subtropical island in southern Japan, squamous cell carc inoma (SCC), especially the well-differentiated form, is prevalent, wh ile this form is relatively rare in both the mainland and other countr ies (e.g. United States of America). More patients with SCC from Okina wa, moreover, were positive for human papillomavirus (HPV) DNA by poly merase chain reaction (PCR) (79%), and harbored HPV types 6, 16 and 18 , in combination. On the other hand, less than 30% of the mainland pat ients were positive for HPV DNA by PCR, Those patients who were positi ve all harbored only one HPV type, Furthermore, in Okinawa, there were a significant number of cases with adenosquamous carcinoma, and they too were positive for HPV DNA,The SCC and the adenocarcinoma cells adj acent to the SCC component in these cases were also positive for HPV D NA, and such adenocarcinoma cells were enlarged in size with relativel y wide cytoplasm. The authors postulate that HPV infects adenocarcinom a cells and changes them to enlarged cells, followed by squamous metap lasia, In this report, HPV DNA was transfected to adenocarcinoma cells (cultured cell lines) and this showed that HPV causes squamous metapl asia. In addition, aberrant expression of p53 was demonstrated in a la rge number of the SCC cases in Okinawa,The enlarged adenocarcinoma cel ls adjacent to the SCC components in adenosquamous carcinomas also sho wed aberrant expression of p53,The recent advances in the studies of a nti-oncogenes, p53, etc, and oncogenes are outlined, It is to be noted that the molecular mechanisms of carcinogenesis in the lung have been studied in general, classifying lung tumors into two groups, namely, small cell carcinoma (SOLO) and non-small cell carcinoma (NSCLC). Howe ver, because human lung cancer is represented by a wide variety of his tologic types, molecular genetic studies according to a more detailed histological subclassification is needed.