Effects of topical tumoricidal agents on port-site recurrence of colon cancer: an experimental study in rats.

BACKGROUND: Reports of metastatic spread of colon and rectal cancer to port sites after laparoscopic resection of potentially curable lesions has raised doubt regarding the efficacy and safety of laparoscopic technology in cancer surgery. Experimental study in animals has led us to believe that the mode of spread of these metastases is via the direct route. We hypothesized, therefore, that we could decrease the rate of trocar-site recurrences by treating the individual port sites with a topical tumoricidal agent. MATERIALS AND METHODS: Male BD-IX rats weighing 240 to 360 g were injected with syngeneic colon cancer to simulate free intraperitoneal cancer spread to trocar sites. All rats were subjected to a sham laparoscopic operation after 2 x 10(5) viable cancer cells had been injected into their peritoneal cavities. Five-millimeter trocars were inserted into each rat after abdominal insufflation to 10 mm Hg. Pneumoperitoneum was maintained for 10 minutes before the trocars were removed simultaneously. Trocar sites were then subjected to one of three treatments, with each animal receiving a maximum of two different treatments. Sites were treated with 70% ethanol (N = 42), povidine/ iodine (N = 40), or no topical treatment (N = 46). Three weeks later, the animals were euthanized and autopsied. Subcutaneous tumors at trocar sites or tumors with >50% volume within the wound were considered implants. RESULTS: Control sites revealed a metastasis rate of 41% (19/46). The tumor implant rate was 36% (15/42) at alcohol-treated sites and 20% (8/40) at sites treated with povidone-iodine (P < 0.05). CONCLUSION: Topical administration of povidone-iodine to trocar wounds after laparoscopic surgery can significantly reduce the incidence of port-site metastasis in a syngeneic animal model of colon cancer.

Characterization and cloning of the E11 antigen, a marker expressed by rat osteoblasts and osteocytes.

A new marker for cells of the osteoblastic lineage was identified by raising monoclonal antibodies against an immortalized rat osteoblastic cell line. Among the different antibodies one was selected which, on tissue sections, strongly reacts with osteoblasts, preosteocytes, and osteocytes. This antibody, designated E11, recognizes an antigen localized at the cell surface. The cDNA encoding the E11 antigen was cloned from a cDNA library prepared from ROS 17/2.8 cells, using a eukaryotic expression system. The E11 cDNA sequence revealed homology with the murine OTS-8/gp38 sequence. In situ hybridization confirmed that E11 mRNA expression in bone is restricted to osteoblasts and osteocytes. The tissue specificity of the E11 expression was studied by immunohistochemistry and Northern blot analysis. Apart from bone, E11-positive cells were also found in lung: namely, the alveolar cells of type I. Epithelial cells of the choroid plexus and endothelial cells of lymphatic vessels were also labeled with mAb E11. These results were confirmed by Northern blot, as the 1.8 kb E11 mRNA transcript was detected in bone and also in lung, brain, and skin. In conclusion, we describe a novel osteoblastic product which is expressed by mature osteoblasts and newly formed osteocytes.