Cumulated Time With Low Bispectral Index Values Is Not Related to the Risk of New Cancer or Death Within 5 Years After Surgery in Patients With Previous or Prevailing Malignancy

Lindholm, Maj-Lis PhD*; Brudin, Lars MD, PhD; Sandin, Rolf H. MD, PhD

doi: 10.1213/ANE.0000000000000097
Patient Safety: Research Report

BACKGROUND: Preclinical data indicate that anesthesia and surgery may promote cancer growth. We previously found no increased risk of malignant disease within 5 years regarding duration of general anesthesia (TANESTH) and time with Bispectral Index (BIS) under 45 (TBIS < 45) in patients without any diagnosis or history of malignancy before or within 1 month after surgery. Because immunocompetence may be different in patients with previous malignant disease, we investigated the corresponding risk in patients with earlier or existing malignant disease at the time of surgery.

METHODS: In a prospective cohort of 766 BIS-monitored patients anesthetized with sevoflurane, new malignant diagnoses and death within 5 years after surgery were retrieved. Cox regression was used to assess the risk of new cancer and all-cause death during follow-up in relation to (TANESTH) and (TBIS <45).

RESULT: Fifty-one patients (6.7%) were assigned 54 new malignant diagnoses within 5 years after surgery. Cancer surgery comprised 387 (51%) of the index operations. Two hundred ninety-three (38 %) of the patients died during follow-up. No relation between TANESTH or TBIS <45 and new malignant disease (hazard ratio [HR] 0.64–1.11 and 0.76–1.30, respectively) or death was found (HR 0.85–1.05 and 0.94–1.16, respectively). Nor were any corresponding significant relations obtained when other thresholds for BIS (i.e., < 30, 40, and 50, respectively) were investigated.

CONCLUSION: In patients with previous or existing malignant disease, neither duration of anesthesia nor increased cumulative time with profound sevoflurane anesthesia was associated with an increased risk for new cancer or death within 5 years after surgery. Monitoring “depth of anesthesia” is not expected to alter the risk of cancer proliferation after surgery.

From the Departments for *Anesthesia and Intensive Care and Clinical Physiology, Lanssjukhuset, Kalmar; Department of Medicine and Health Sciences, University Hospital Linköping, Linköping; and Section for Anesthesiology and Intensive Care Medicine, Karolinska Institutet, Stockholm, Sweden.

Accepted for publication November 26, 2013.

Funding: FORSS (The Research Council in South-East Sweden) financed study personnel who collected raw data. BIS monitors were loaned and sensors provided by former Aspect Medical Systems, Newton, MA, now Covidien, Boulder, CO. Aspect Medical Systems/Covidien also financed downloading of BIS trends by their local representative in Sweden, and contributed to financing the dedicated study personnel.

Conflict of Interest: See Disclosures at the end of the article.

Reprints will not be available from the authors.

Address correspondence to Maj-Lis Lindholm, PhD, Department for Anesthesia and Intensive Care, Lanssjukhuset S-39185 Kalmar, Sweden. Address e-mail to majlisl@ltkalmar.se.

© 2014 International Anesthesia Research Society