Partial colon resection as a promotor of cancer growth in the rat.

Sprague-Dawley rats were treated with dimethylhydrazine (DMH) once a week for three months. After a treatment-free period of five months, they were subjected to minimal colon resection with an end-to-end anastomosis. Autopsy (one year after the discontinuation of DMH treatment, and seven months after surgery) demonstrated anastomotic tumors in 50% of the animals. Conclusions were that the carcinogen had induced genetic changes in the nonmigrating stem cells in the colonic crypts and that the chronic reparative process resulting from surgical trauma may have promoted colonic cells to induce tumors at the suture line.