The post-surgical inflammatory response provokes enhanced tumour recurrence: a crucial role for neutrophils.

BACKGROUND/AIMS Peritoneal trauma activates a cascade of peritoneal defence mechanisms responsible for postoperative intra-abdominal tumour recurrence. After peritoneal trauma, inflammatory cells and soluble factors are present in the abdominal cavity and can be captured in lavage fluids. The present study evaluated which component enhances intra-abdominal tumour recurrence. Furthermore, we evaluated which inflammatory cells are present and studied the influence of anti-neutrophil serum (ANS) on peritoneal tumour recurrence. METHODS In a peritoneal trauma model in rats, postoperative lavage fluids were collected and separated into cellular and supernatant components. Both components were injected in naïve rats together with CC531s colon carcinoma cells. In a second experiment, rats were treated with one or three doses of ANS. RESULTS Intraperitoneal injection of naïve recipients with inflammatory cells or supernatant resulted in significant tumour recurrence. Severe peritoneal trauma provoked significant intra-abdominal neutrophil influx which could be prevented by ANS. Treatment with one dose did not affect blood cell counts and significantly reduced tumour recurrence. Treatment with three doses of ANS decreased blood lymphocytes, monocytes, and neutrophils and induced tumour load. CONCLUSIONS Neutrophils play a crucial role in postoperative adhesion and growth of spilled tumour cells after surgical peritoneal trauma. Prevention of peritoneal neutrophil influx reduces local tumour recurrence.