Epidural Analgesia and Recurrence after Colorectal Cancer Surgery: A Danish Retrospective Registry-based Cohort Study

Background: Surgery is the main curative treatment for colorectal cancer. Yet the immunologic and humoral response to surgery may facilitate progression of micro-metastases. It has been suggested that epidural analgesia preserves immune competency and prevents metastasis formation. Hence, the authors tested the hypothesis that epidural analgesia would result in less cancer recurrence after colorectal cancer surgery. Methods: The Danish Colorectal Cancer Group Database and the Danish Anesthesia Database were used to identify patients operated for colorectal cancer between 2004 and 2018 with no residual tumor tissue left after surgery. The exposure group was defined by preoperative insertion of an epidural catheter for analgesia. The primary outcome was colorectal cancer recurrence, and the secondary outcome was mortality. Recurrences were identified using a validated algorithm based on data from Danish health registries. Follow-up was until death or September 7, 2018. The authors used propensity score matching to adjust for potential preoperative confounders. Results: In the study population of 11,618 individuals, 3,496 (30.1%) had an epidural catheter inserted before surgery. The epidural analgesia group had higher proportions of total IV anesthesia, laparotomies, and rectal tumors, and epidural analgesia was most frequently used between 2009 and 2012. The propensity score-matched study cohort consisted of 2,980 individuals in each group with balanced baseline covariates. Median follow-up was 58 months (interquartile range, 29 to 86). Recurrence occurred in 567 (19.0%) individuals in the epidural analgesia group and 610 (20.5%) in the group without epidural analgesia. The authors found no association between epidural analgesia and recurrence (hazard ratio, 0.91; 95% CI, 0.82 to 1.02) or mortality (hazard ratio, 1.01; 95% CI, 0.92 to 1.10). Conclusions: In colorectal cancer surgery, epidural analgesia was not statistically significantly associated with less cancer recurrence.