Development of an animal model to study the biology of recurrent colorectal cancer originating from mesenteric lymph system metastases.

We developed an animal model to study the biology and therapy of local-regional recurrent colorectal cancer. Syngeneic tumor cells or human colon carcinoma cells, respectively, were injected into the lymphoid follicle of the cecum of conventional mice or athymic nude mice. The cecum was resected (at a distant site) at various time points after the injection. Recurrent disease at the site of resection and in regional mesenteric lymph nodes was found in most of the injected mice, even in those whose cecum was resected 10 min after injection. The injection of tumor cells into the lymphoid follicle of the cecum introduces tumor cells into the lymph system of the cecum and the draining mesenteric lymph nodes, and these few cells, which cannot be detected at the time of operation, are the source of recurrent disease. This new animal model should allow us to study the biology and therapy of local and regional colorectal cancer.