To the Editor:
I read with great interest the recent publication in Anesthesiology regarding the potential effect of epidural analgesia on cancer recurrence in patients undergoing colon surgery.1The study1reported that epidural analgesia showed no overall benefit—a finding that is in contrast to those of previous investigators.2,3However, Gottschalk et al .1report a limited beneficial effect in older patients as observed in post hoc analysis.
Is it possible that the results of the study by Gottschalk et al .1are different from those previously reported because their epidurals were not necessarily initiated before surgical incision? As a result of this methodologic preference, readers do not know whether these epidurals were functioning intraoperatively. This information is very important because, if the epidural was not used intraoperatively, suppression of the surgical stress response (and the resulting immunosuppression) may have not occurred in many of the patients in this study. In a similar study, Christopherson et al. 2ensured that an analgesic level was attained before surgical incision—which may explain why an overall benefit was shown in that trial, but not in the current one.
Why patients older than 64 yr had some benefits remains uncertain. It could be a random statistical finding, as noted by the authors.1Alternatively, one can assume that these patients may have received less narcotic than their younger counterparts—or that these patients take drugs that may play a role in cancer recurrence, such as β blockers and statins.4
University of Virginia, Charlottesville, Virginia. firstname.lastname@example.org