The study to which Yoshida, Kobayashi, and Miyata are responding shows that tumor establishment and growth are facilitated after laparotomy as compared with laparoscopy. Our laboratory and others' have previously shown that cellular immune response is preserved after laparoscopic vs open procedures.1-3 Yoshida and his colleagues offer data that support a benefit to laparoscopic procedures and they suggest that this benefit is due to the lack of exposure of the peritoneal cavity to air.
The data presented do not support the conclusion that exposure to air is responsible for the differences found in the above studies. Yoshida and his colleagues did not control for the variable of surgical trauma. No group having laparotomy in an environment that avoided exposure of the peritoneum to air was included nor was any surgical procedure performed in the group that was insufflated with carbon dioxide. An insufflation group using air as