Malignant disease within 5 years after surgery in relation to duration of sevoflurane anesthesia and time with bispectral index under 45

Abstract

Background: Surgery, general anesthesia, and related events have been implicated to promote cancer proliferation. We investigated the incidence of cancer within 5 years after surgery in relation to duration of anesthesia (T(ANESTH)) and also by time with bispectral index (BIS) under 45 (T(BIS<45)) serving as a proxy for more profound anesthesia exposure.

Methods: New malignant diagnoses after surgery under sevoflurane anesthesia were obtained in a prospective cohort of 2972 BIS-monitored patients without any clinically diagnosed malignant disease at the time of index surgery. The risk of cancer during follow-up in relation to T(ANESTH) and T(BIS<45) was assessed by Cox regression. The cancer incidence in this surgical population was compared with the incidence in a standardized general population by calculation of standard incidence ratio.

Results: One hundred twenty-nine patients (4.3%) were assigned 136 new malignant diagnoses within 5 years after surgery. No relation between T(ANESTH) or T(BIS<45) and new malignant disease was found, nor were any significant relations obtained when other thresholds for BIS (i.e., <30, <40, and <50, respectively) were used in the calculations. The standard incidence ratio for new malignant disease was 1.37 (confidence interval, 1.15-1.62).

Conclusion: Neither duration of anesthesia nor increased cumulative time with profound sevoflurane anesthesia was associated with an increased risk for new malignant disease within 5 years after surgery in previously cancer-free patients.