Promotional Role of Lymphoid Nodules in Colorectal Cancer: Implicationsfor Endoscopic Screening and Prevention

Abstract

This report examines the anatomical distribution of colorectal cancer CRC in the human large bowel. The find- ings indicate the high occurrence of cancer in the rectum. The reason for the high incidence of rectal cancer is explored. Published data were compiled and analyzed to correlate the high occurrence of CRC in the human rectum to the high oc- currence of lymphoid nodules (LNs). Histopathologic classification and distribution of CRC types was reviewed. Statisti- cal findings reveal a significant (p < 0.01) positive relationship between number of LNs and number of CRCs. Histopa- thological findings indicate that LNs promote epithelial hyperplasia and a nonpolyploid pathway of cancer development especially in the rectum.The findings of a 7 to 8 fold higher density of rectal cancer per cm length in the human rectum compared to the other segments of the large bowel emphasize the importance of careful endoscope screening for the de- tection of nonpolyploid rectal cancers. Review of human and rat literature suggests that drugs that suppress the immune system and that aspirin, an anti-inflammatory agent,may work to reduce risk of CRC via their effect on lymphoid nodules.