Does General Anesthesia Choice Impact Breast Cancer Survival?
Breast cancer is one of the most common forms of cancer. Despite an increase in global survival rates among individuals with breast cancer, many still lose their lives. Part of what makes the management of breast cancer so complex are the many factors that may contribute to patient mortality, such as surgery.
Prior studies have raised questions on the role that anesthesia may have on long-term survival in individuals with breast cancer. In a follow-up to the Cancer and Anesthesia clinical trial, the authors further examined this relationship.1 They hypothesized that the anesthetic propofol will have an advantage over sevoflurane in 5-year survival of patients undergoing breast cancer surgery. However, the results of the study indicated that the choice of general anesthesia in breast cancer surgery did not impact the rate of overall survival of these patients.
To learn more about the study, Consultant360 reached out to the lead study author, Mats Enlund, MD, PhD, who is an associate professor at the Center for Clinical Research at Uppsala University in Sweden.
Consultant360: What prompted your team to study the outcomes associated with propofol and sevoflurane in breast cancer surgery?
Mats Enlund, MD, PhD: We started with a retrospective study published in 2014.2 We chose colorectal and breast cancer to focus on as we expected a large number of cases for these cancer types which had different tumor biology characteristics, as well as data for both superficial and deep surgery to be available. When we later decided to start a randomized controlled trial, we made the same choice because we had the numbers for an accurate power calculation, and again access to a large number of patients.3
C360: Your study notes that patient-related factors, such as tumor characteristics, were the most important predictors of survival. Did the impact of any of these factors surprise you, or did you anticipate this?
Dr Enlund: Already in our first retrospective study we could not see any difference in long-term survival for breast cancer in relation to the choice of anesthetic.2 Later, we conducted two different observational studies concerning breast cancer specifically. One included patients from seven different Swedish hospitals and one was a national study.4,5 In both studies the result was the same, which was that there was no difference in survival between the anesthetic agents, which was also in line with three studies from Asia.6-8 So we were not surprised by the results for the breast cancer cohort in our trial.
C360: What is the current standard of care for choosing a general anesthesia for patients undergoing breast cancer surgery?
Dr Enlund: I guess general anesthesia with or without paravertebral block predominates. However, it is possible to rely on a paravertebral block in combination with sedation (or with the patient awake), with or without the addition of local anesthesia. For very fragile patients, it is the preferred method.
C360: What are the next steps for research in this area?
Dr Enlund: Our next step is to analyze the colorectal cancer cohort at the end of this year. This part of our trial took much longer to complete, partly because we needed many more patients and partly because of a severe delay due to the pandemic. Because randomized controlled trials are costly to conduct both in time and financially, we have started using national Swedish quality registers, such as our national study.4 Similar studies on colorectal cancer and bladder cancer are on the way and there are more to come. We hope that the retrospective analyzes of these prospectively collected data at the national level will be more reliable than usual retrospective studies.
1. Enlund M, Berglund B, Enlund A, et al. Impact of general anesthesia on breast cancer survival: a follow-up of a pragmatic, randomized, controlled trial, the CAN-study, comparing propofol and sevoflurane. eClinicalMedicine. 2023;60;102037. doi:10.1016/j.eclinm.2023.102037.
2. Enlund M, Berglund A, Andreasson K, Cicek C, Enlund A, Bergkvist L. The choice of anaesthetic— sevoflurane or propofol —and outcome from cancer surgery: a retrospective analysis. Ups J Med Sci. 2014;119:251–261. doi:10.3109/03009734.2014.922649.
3. Enlund M, Enlund A, Berglund A, Bergkvist L. Rationale and design of the CAN Study: an RCT of survival after propofol- or sevoflurane-based anesthesia for cancer surgery. Curr Pharm Des. 2019;25:3028–3033. doi:10.2174/1381612825666190705184218.
4. Enlund M, Berglund A, Ahlstrand R, et al. Survival after primary breast cancer surgery following propofol or sevoflurane general anesthesia: a retrospective, multicenter, database analysis of 6305 Swedish patients. Acta Anaesthesiol Scand. 2020;64:1048–1054. doi:10.1111/aas.13644.
5. Enlund M, Berglund A, Enlund A, Bergkvist L. Volatile versus propofol general anesthesia and long-term survival after breast cancer surgery: a national registry retrospective cohort study. Anesthesiology. 2022;137:315–326. doi:10.1097/ALN.000000000000430910.1097/ALN.0000000000004309.
6. Kim MH, Kim DW, Kim JH, Lee KY, Park S, Yoo YC. Does the type of anesthesia really affect the recurrence-free survival of breast cancer surgery? Oncotarget. 2017;8(52):90477-90487. doi:10.18632/oncotarget.21014.
7. Yoo S, Lee HB, Han W, et al. Total intravenous anesthesia versus inhalation anesthesia for breast cancer surgery. Anesthesiology. 2019;130:31–40. doi:10.1097/ALN.0000000000002491.
8. Huang YH, Lee MS, Lou YS, et al. Propofol-based total intravenous anesthesia did not improve survival compared to desflurane anesthesia in breast cancer surgery. PLoS One. 2019;14:e0224728. doi:10.1371/journal.pone.0224728