Background: Lymph node metastases and peritoneal carcinosis, occurring as a result of gastrointestinal cancer, reduce the likelihood that conventional therapy will be adequate to remove the cancer. Although diagnostic techniques have greatly improved, it is not always possible to diagnose the entire extent of the metastases. Often, peritoneal micrometastases are not visible and may be missed during laparoscopic or open surgery.
Methods: Peritoneal carcinosis was induced in WAG-Rij rats (n = 6), by laparoscopically implanting 1,2-dimethylhydrazine-induced colon carcinoma tumor cells (CC531, 5 x 10(5)) at multiple sites within the peritoneal cavity. After 12 days of tumor growth, the animals were given delta-aminolevulinic acid (ALA) (5 mL, 3% solution in 0.17 mol/L NaHCO3) by peritoneal lavage. The tumors were visualized laparoscopically using both white and blue light (D-light, Karl Storz, Tuttlingen, Germany). Fluorescence was detected by using a modified CCD camera and a special observation filter incorporated into the laparoscope.
Results: Peritoneal carcinoma foci ranging in size from 0.05 to 2.0 cm were clearly visible laparoscopically with conventional white light (n = 142). After blue light excitation, all 142 tumors identified with white light were also identified by fluorescence. There were an additional 30 tumors that could only be identified by blue light-induced fluorescence and were histologically confirmed to be derived from colon carcinoma tumor cells.
Conclusions: Peritoneal colonic carcinoma foci were detected laparoscopically after intraperitoneal lavage with delta-aminolevulinic acid (ALA) and excitation with blue light. These experiments demonstrate that fluorescence laparoscopy is an important technique for the staging of gastrointestinal cancer, including colorectal cancer, because of the enhanced ability to detect small cancerous foci.