The authors found no association between duration of anesthesia and time BIS was < 45 with the risk of new malignancy or death. (Image source: Thinkstock)

The authors found no association between duration of anesthesia and time BIS was < 45 with the risk of new malignancy or death. (Image source: Thinkstock)

Anesthetics are known to affect the immune response, yet recently in this journal it was shown that the risk of malignant disease within 5 years postoperatively could not be associated with the duration of general anesthesia and time with Bispectral Index (BIS) under 45 in patients without a history of malignancy.  What about patients with previous or existing malignant disease at the time of surgery?  Does duration of general anesthesia and time with BIS < 45 affect the risk of malignant disease within 5 postoperative years in this group of patients?

Dr. Maj-Lis Lindholm, Department for Anesthesia and Intensive Care, Kalmar, Sweden, and colleagues studied the risk of new malignancy in 766 patients with previous or prevailing malignant disease at the time of surgery.  The results of their analysis are summarized in the article titled “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,” which is published in the current issue of Anesthesia & Analgesia.

In this patient group, the authors found 51 patients (6.7%) who developed 54 new malignant diagnoses within 5 years after the index operation. Twenty-one (41%) of the 51 patients with a new malignant diagnosis died within the study period.  The authors found no relation between duration of anesthesia and time BIS was < 45 with the risk of new malignancy or death.

Is sample size of this study large enough to definitely draw such a conclusion?  Might there be a subset of patients in whom there is such an association?  Finally, might different anesthetics result in a different outcome than others?  Though imperfect, investigations such as this are very helpful in view of the interactions (if any) of general anesthesia upon such things as cancer incidence or recurrence.