The anaesthesia technique used during breast cancer surgery may affect cancer recurrence and survival, Danish researchers report.
In a small study that followed 77 breast cancer patients, researchers found the combination of a general anaesthetic plus injections of a nerve block resulted in increased survival and fewer recurrences, said Dr Palle Steen Carlsson, a researcher at the Aarhus University Hospital in Denmark.
A six-year follow-up found that 13% of patients who got the combination had their cancer recur versus 37% of those who got anaesthesia alone. And 10% of those in the combination group died compared to 32% of those given anaesthesia alone.
The idea that the anaesthesia technique used during breast cancer surgery affects results is evolving, anaesthesiologists say, and needs more study. Carlsson found a link between the two, but her study didn't show a direct cause-and-effect relationship. She is scheduled to report her findings at the American Society of Anaesthesiologists' annual meeting in San Francisco.
Carlsson acknowledged the study's limitations. "The weakness of our study is the size," she said.
During cancer surgery, tumour cells released into the blood can implant in lymph nodes and other organs, she said. The immune system kicks in to fight these cells, but surgery and anaesthesia can impair the immune system.
Carlsson can't say for sure why women who got the nerve block plus anaesthesia tended to fare better. One theory is that better pain relief during and after surgery reduces the stress response to the procedure, she said. Or perhaps the need for fewer narcotic painkillers after surgery reduces the risk of cancer spreading.
In the study, Carlsson randomly assigned the 77 patients to general anaesthesia plus injections of saline or general anaesthesia plus injections of local anaesthetic (this is called a paravertebral block) about an inch from the middle of the spine.
Besides differences in recurrence and survival, medical records six years later showed fewer opioids for pain relief were needed by the women who got the combination approach.
In an earlier study, researchers found that the combination of general anaesthesia and regional anaesthesia reduced recurrences and the spread of breast cancer four-fold, but that study looked back at medical records. Carlsson said her study is believed to be the first to follow patients forward.
The concept has been a hot topic for several years among aneasthesiologists, said Dr Michael Lew, professor and chairman of anaesthesiology at the City of Hope Comprehensive Cancer Center in Duarte, California. Lew was not involved in the study.
"[This study] is exciting and a step in the right direction," he said. "However, [Carlsson] is correct in saying there needs to be more numbers."
Opioids inhibit natural killer cells
More information is expected soon, Lew said, citing a clinical trial under way at the Cleveland Clinic and elsewhere. It will compare different anaesthesia approaches used in more than 1 100 breast cancer patients over five years and evaluate differences in outcomes.
Until more findings are in, Lew suggested that women facing breast cancer surgery tell their surgeon they want a general anaesthetic with as few opioids as possible. "The opioids inhibit natural killer cells [that attack roaming cancer cells]," he said.
Lew said he sometimes gives a general anaesthetic plus intravenous anti-inflammatory medicine to combat pain.
Studies presented at meetings typically are considered preliminary until published in a peer-reviewed medical journal.
To learn more about breast cancer, visit the American Cancer Society.
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