Postoperative intra-abdominal infection and colorectal cancer recurrence: A prospective matched cohort study of inflammatory and angiogenic responses as mechanisms involved in this association

Abstract Background Anastomotic leakage is associated with higher rates of recurrence after surgery for colorectal cancer. However, the mechanisms responsible are unknown. The aim was to investigate the inflammatory and angiogenic responses in patients undergoing surgery for colorectal cancer who had postoperative intra-abdominal infection, and to compare the results with patients without complications. Methods Consecutive patients undergoing surgery for colorectal cancer with curative intent were included. Patients who had an anastomotic leak or intra-abdominal abscess were included in the infection group and matched with patients who had an uncomplicated postoperative course. IL-6 and VEGF were measured in serum and peritoneal fluid. Results Serum concentration of IL-6 was higher in the infection group ( n  = 30) compared with the control group ( n  = 30) on day 4 (infection: 42.3 [27.6–1473.2] versus control: 0.6 [0.6–17.1] pg/ml; p  = 0.008). IL-6 in peritoneal fluid was higher in the infection group at 48 h and day 4 (infection: 1000.2 [995.4–1574.0] versus control: 90.3 [35.2.6–106.1] pg/ml; p  = 0.001). Serum VEGF was higher in the infection group on day 4 (infection: 1128.6 [427.3–10000.0] versus control: 438.3 [214.1–677.6] pg/ml; p  = 0.001). Peritoneal VEGF concentration was higher in the infection group at 48 h and day 4 (infection: 10000.0 [2563.0–10000.0] versus control: 477.8 [313.5–814.4] pg/ml; p  = 0.001). Two-year recurrence rate was higher in patients with infection (infection: 30% versus control: 4%; p  = 0.001). Conclusions Intra-abdominal infection increases IL-6 and VEGF after surgery for colorectal cancer. Amplification of inflammation and angiogenesis might be one of the mechanisms responsible for the higher recurrence rate observed in patients with anastomotic leakage or intra-abdominal abscess.