ETHNIC OR ENVIRONMENTAL DIFFERENCES IN DISPARATE GEOGRAPHIC REGIONS MAY INFLUENCE THE HISTOLOGY OF FLAT COLORECTAL NEOPLASIAS

Histologic sections of endoscopically flat colorectal polyps removed i n Tokyo and Stockholm were reviewed A total of 178 flat colorectal neo plasias (88 from the Tokyo Medical College Hospital, Tokyo and 90 from the Karolinska Hospital, Stockholm) were classified following strict histologic criteria by two different pathologists (one Swedish and the other Japanese). The number of polyps with high grade dysplasia, with intramucosal carcinoma and with invasive carcinoma were significantly higher (p < 0.001) in Tokyo (61.4% or 54/88) than in Stockholm (15.0% or 14/90). The present results suggest that flat colorectal neoplasic polyps may be histologically more ''severe'' and more ''aggresive'' i n Japanese than in Swedish patients. The possibility that more ''advan ced'' lesions had been inadvertently removed in Tokyo was discounted a s Japanese endoscopists were also instrumental in excising many of the flat colorectal polyps in Stockholm. Ethnic and/or environmental diff erences seem to play a crucial role in the evolution of flat colorecta l neoplasic polyps from LGD and HGD, to intramucosal and to invasive c arcinoma.