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Wide awake surgery keeps killer cells on the alert

点击量:   时间:2019-02-27 09:17:01

By Vincent Kiernan PATIENTS undergoing surgery for cancer might stand a better chance of a full recovery if they remain conscious during the operation, says a surgeon from Pennsylvania. General anaesthetic does more than simply knock out patients, it also seems to depress a key element of the immune system that attacks cancer cells, says Walter Koltun, an assistant professor of surgery at Pennsylvania State University’s Hershey Medical Center. Koltun’s research suggests that patients would be better off having an epidural anaesthetic, particularly if they already have a weak immune system. An epidural prevents pain signals from travelling along the spinal cord to the brain. The patient feels no pain but remains conscious. Koltun compared 10 patients who underwent colon surgery under general anaesthetic with 10 who had the operation with an epidural. He analysed blood samples from all 20 patients shortly after surgery and found that those under general anaesthetic had fewer active natural killer cells than those given the epidural. Killer cells are the cells of the immune system that attack tumour cells. Koltun also found that the unconscious patients had higher levels of stress-related hormones such as adrenaline and cortisol in their blood. This suggests that although general anaesthetic prevents a patient from feeling pain, says Koltun, the unconscious brain nevertheless registers the trauma of surgery and initiates the production of hormones that accompany danger or injury to the body. Unfortunately, these hormones temporarily depress the activity of the immune system. “You’re not conscious of it, but your body still responds,” he says. By contrast, because the epidural blocks the transmission of nerve impulses to the brain, the brain does not trigger the stress response and the killer cells are left unaffected. Interfering with the natural killer cells could be particularly bad news for cancer patients, says Koltun. Surgery to remove tumours often dislodges a few tumour cells, which are carried around the body. Normally, active killer cells would destroy roving tumour cells, but a general anaesthetic suppresses them just when the patient needs them most, says Koltun. Although many people would prefer to be unconscious when they have an operation, Koltun says that patients who have an epidural are just as oblivious as those under general anaesthetic. The epidural blocks all sensation, from the nipples down to the knees. “Most patients don’t even remember their surgery,