Short- and long-term results after laparoscopic vs conventional colon resection in a tumor-bearing small animal model

We designed a study to evaluate the short- and long-term outcome of laparoscopic vs conventional colonic resection in a tumor-bearing small animal model.

We operated on male BD X rats (260-300 g), performing either laparoscopic (n = 9) or open colon resection (n = 9) in order to evaluate stress and immunological response to laparoscopic vs conventional colon resection. A third group (n = 9) underwent anesthesia only. Immediately before and after surgery, as well as at 1, 7, and 21 days postoperatively, a sample of 1 ml blood was taken from the retrobulbar venous plexus. Stress (corticosterone) and immune parameters (neopterine and IL-1 beta, IL-6) and body weight as a parameter of postoperative recovery were measured to identify short-term alterations. Long-term changes were evaluated in terms of survival time and at autopsy by measuring the tumor weight and the number of tumor infiltrated nodules (histology).

The analysis of variance (ANOVA) showed significant differences between the three groups over a period of 1 week (p < 0.001 for corticosterone, p = 0.009 for neopterine, p = 0.04 for IL-1 beta, p = 0.024 for IL-6). Additionally, significant differences by t-test were found between the laparoscopic (minor alteration) and conventional (major alteration) group regarding corticosterone (p = 0.0015), neopterine (p = 0.0024), IL 1-beta (p = 0.033), and IL-6 (p = 0.015) at the end of the operation. One week after the operation, the body weight was different depending on the type of operative procedure: 7 days postoperatively the rats lost 8% of their body weight after open surgery but only 4.3% after laparoscopic surgery. After anesthesia only, body weight increased by approximately 4.8%. The medium survival time for the lap group was 44 days, whereas it was 44.1 days for the conventional group and 46 days for the anesthesia group (ANOVA p = 0.625). The number of nodules was 13.5 in the laparoscopic group 10.5 in the open group, and 7.4 in the anesthesia group, (ANOVA p = 0.119). The tumor weight was 6.8 g in the laparoscopic group, 6.4 g in the open group, and 5.04 g in the anesthesia group (ANOVA p = 0.874).

In a tumor-bearing small animal model, laparoscopic colon resection alters the stress and immune system less than open colon resection. This observation has no implications for the long-term results as measured by survival time and at autopsy. Therefore, laparoscopic colon resection has a short-term benefit and has no negative effect on long-term results compared to conventional operative procedures.