[Tumor cells in peritoneal irrigation fluid in conventional and laparoscopic surgery for colorectal carcinoma]

In minimal invasive cancer surgery port-side metastases are observed. The most plausible theory of there development is by tumor cell contamination during the operation. This prospective controlled study was designed to evaluate the moment of liberation of cancer cells, frequency of implantation and follow up after laparoscopically assisted and open resections.

The peritoneal cavity is washed out 4 times with 200 mls of Ringer' solution (at the beginning of the operation, after central ligation of the vessels, after mobilisation of the cancer and at the end). The aspirate is centrifuged and stained by Papanicolaou. Follow up is by the protocol of the swiss cancer study group. Up to now 71 patients (35 laparoscopical, 4 conversions, 27 open, 5 peritoneal carcinomatosis) have entered the study.

Positive cytology was found in 4/35 laparoscopic and 5/27 open resections. Excluding the first wash out 1/35 (3%) and 3/27 (11%) respectively were positive, however, none at the end of operation. Only in 4/5 peritoneal carcinomatosis tumor cells were present in the final wash out. Median follow up of patients with positive cytology was 9,5 months [6-15] for laparoscopy and 8 months [2-11] for open surgery. Three from each group were followed more than 7 months. No recurrence or port-side metastasis was observed. In patients with negative cytology two cancer progressions were detected.

The significance of free tumor cells for the development of implantation metastases is unclear. In 8/13 patients cytology was positive at the beginning of the operation, and only patients with a peritoneal carcinomatosis demonstrated cancer cells in the final wash out. In laparoscopy no cells were found in the second and one in the third wash out, resulting in a 1/35 risk of cancer cell liberation. Whether this patient will develop a port-side metastasis is unknown. He is followed for 8 months without tumor progression. We believe that a positive cytology alone cannot be the reason for implantation metastases.

Using the minimal invasive technique for colorectal carcinoma resection liberation of cancer cells tends to be less compared with open surgery. For further conclusions the time of follow up is not yet long enough.