Intraperitoneal exfoliated cancer cells in patients with colorectal cancer

The aims of this study were to evaluate potential predictors of exfoliated free cancer cells in the peritoneal cavity and to assess intraoperative peritoneal lavage cytology as a prognostic indicator in patients with colorectal cancer.

From 1985 to 1987, intraoperative peritoneal lavage cytology was performed in 140 patients with colorectal cancer. Among them, 88 patients underwent curative resection and 52 patients had noncurative surgery. Cytology was examined twice, i.e., immediately after opening the peritoneal cavity (precytology) and just before closing the abdomen (postcytology). One hundred milliliters of saline was poured into the peritoneal cavity and it was retrieved by suction after irrigation. Cytologic examination was performed after staining with Papanicolaou, Giemsa, periodic acid-Schiff, and Alcian blue stains.

Among the 140 patients examined, the incidence of positive cytology in the prelavage was 15 percent, and that in the postlavage was 9 percent, although it was 16 percent in either lavage. Among patients with curative resection, 10 percent had positive cytology. Seven characteristics were identified as features of tumors which are prone to exfoliate cells into the peritoneal cavity: 1) macroscopic peritoneal dissemination, 2) liver metastasis, 3) more than 20 ml of ascites, 4) ulcerated tumors without definite borders, 5) invasion of the serosal surface or beyond, 6) semiannular or annular shape, and 7) moderate or marked lymphatic invasion. In patients undergoing curative surgery, among these features, circumferential involvement was the only one correlated closely with positive cytology (P < 0.02). Positive cytology was associated with a worse outcome. In patients who were resected curatively, the postcytology had a stronger influence on local recurrence than the precytology; the local recurrence rate in patients with positive postcytology was higher than in those with negative postcytology, regardless of the precytology. All patients with cancer cells in the peritoneal cavity at the end of surgery had recurrence.

Seven characteristics were identified as risk factors for exfoliation of cancer cells into the peritoneal cavity in patients with colorectal cancer. These findings may be helpful for the choice of laparoscopic surgery in this era of increasing port-site metastases after laparoscopic procedure. The results of peritoneal lavage cytology at the end of surgery were correlated with the long-term postoperative outcome of colorectal cancer. Thus, meticulous follow-up and possibly adjuvant chemotherapy may be beneficial for patients with free cancer cells in lavage fluid, even after curative surgery.