This week's artwork was donated by Dathan, a pediatric cancer patient who received treatment at The Children's Hospital of Philadelphia . A hypothesis for the etiology of adenoma-carcinoma sequence in large bowel neoplasms is proposed based on the results of previous studies. In populations with a low incidence of colorectal cancer, the incidence of adenomas varies greatly. Furthermore, the subsite distribution of adenomas within the colon and rectum differs from that of carcinomas.
Large adenomas have a greater malignant potential than small adenomas.
The subsite distribution and incidence of large adenomas approximate those of colorectal cancer. Thus, the major factor in determining carcinoma incidence is the one that causes adenomas to grow to a large size, rather than the one that actually causes malignant change. A genetic predisposition to adenomas has been proposed, with a recessive gene making a person adenoma-prone. It is suggested that environmental agent A, which causes adenomas, will act in adenoma-prone cells to create small adenomas. It is suggested that the agent causing the adenomas to grow is a bacterial metabolite of the bile acids already incriminated in the etiology of large-bowel cancer.