Washington, Sept 26 : General anesthesia for surgery does not increase the risk of new-onset cancer, a new research has found.

Recent studies have raised the possibility that anesthesia or other factors around the time of cancer surgery may increase the risk of cancer recurrence. One theory is that anesthesia affects the immune system, allowing otherwise dormant cancer cells to progress into clinical disease.

But the new report has found no link between the duration or depth of general anesthesia and the subsequent risk of developing cancer.

“Neither duration of anesthesia nor increased cumulative time with profound sevoflurane anesthesia was associated with an increased risk for new malignant disease within five years after surgery in previously cancer-free patients,” concludes the study by Maj-Lis Lindholm, Ph.D., and colleagues of the Karolinska Institute, Stockholm.

The researchers analyzed data on nearly 3,000 Swedish patients undergoing surgery with the inhaled general anesthetic sevoflurane. None of the patients had any known cancer at the time of the surgery.

The duration and depth of anesthesia were analyzed as predictors of the later risk of cancer. (Depth of anesthesia was assessed using technique called bispectral index [BIS] monitoring.)

Five years after surgery, 4.3 percent of the patients had developed cancer.

On analysis adjusting for other factors, there was no association between the duration of anesthesia and the risk of developing cancer during follow-up.

Cancer risk was also unrelated to time spent at various depths of anesthesia, based on different BIS cutoff points.

The study has been published in the journal Anesthesia amd Analgesia. (ANI)