The point of conversion in laparoscopic colonic surgery affects the oncologic outcome in an experimental rat model

Approximately 20% of laparoscopic colonic tumor resections result in conversion to open surgery. This result may be related to an increased risk in terms of the oncologic outcome. This study aimed to investigate the oncologic consequences of early and late conversion in laparoscopic colonic surgery.

For this study, 45 male WAG-Rij rats were randomized into three operation groups of 15 animals each: laparotomy (LT group), laparoscopy followed by early conversion after 20 min (EC group), and laparoscopy followed by late conversion after 40 min (LC group). The total procedure time for the LT and EC groups was 60 min, compared with 80 min for the LC group. Hematogenous metastatic spread was induced in each operation group by tumor cell inoculation of a rat colon adenocarcinoma (CC 531) into the portal vein after 15 min of surgical intervention. A cecal resection was performed after 30 min in the LT and EC groups and after 50 min in the LC group. On day 28 after surgery, hepatic tumor growth was evaluated by measuring the diameter of tumor nodules, the tumor volume, the weight of the liver, and the cancer index.

Hepatic tumor volume was significantly increased after LC than after EC (p = 0.01) and LT (p = 0.04). The liver weights in the LC group were significantly higher than in the EC (p = 0.01) and LT (p = 0.01) groups. No significant difference between EC and LT was observed in any parameters surveyed.

The LC procedure resulted in greater tumor growth than EC and LT. The EC procedure did not lead to significantly more hepatic tumor growth than the same procedure performed using the conventional open technique. From the oncologic point of view, an early decision for conversion must be recommended as soon as any prolonged operating time has to be hypothesized.