MedWire News: Using regional rather than general anesthesia during cancer surgery is unlikely to have a large influence on patients’ risk for recurrence, research suggests.

There are several trials of general versus regional anesthesia during cancer surgery in progress, but these are unlikely to produce results for several years.

The current findings emerge from a long-term follow-up of the MASTER trial, which randomly assigned cancer patients to general or general plus regional anesthesia, but was not designed to gauge the effect of the intervention on recurrence rates.

The trial “was well powered to detect a one-third treatment effect but lacked power to reliably detect smaller effects that might still be of considerable clinical importance, particularly for individual types of cancer,” caution the researchers, led by Paul Myles (Alfred Hospital, Melbourne, Australia).

All patients in the trial were undergoing major abdominal surgery for cancer and received general anesthesia, but were randomly assigned to also receive either regional anesthesia (epidural) during surgery with postoperative regional analgesia, or post-operative opioids only. For the current study, the researchers analyzed data on 230 patients with complete follow-up from the epidural group and 216 patients from the non-epidural group.

Post-surgical cancer recurrence risk is thought to be raised by the surgical stress response, use of volatile anesthetics, and use of opioids, so giving patients regional anesthesia should in theory reduce or eliminate these additional risks.

Studies in animals and observational studies in patients have largely supported the theory.

But over 9 to 15 years of follow-up of MASTER trial participants, the median recurrence-free survival was similar in both treatment groups, at 2.6 years among patients who received an epidural and 2.8 years among those who did not.

Survival rates over 5 years were 42% and 44% in the epidural and non-epidural groups, respectively, and the corresponding recurrence-free survival rates were 40% and 43%. These small differences between the groups were not statistically significant.

“At the very least, our results suggest that in vitro, animal, and observational human data about regional block and recurrence of cancer should be extrapolated to patients with considerable caution,” say Myles et al.

“Although compelling short-term reasons exist to use epidural analgesia in many patients, reducing the long-term risk of recurrence of cancer may not be among them.”