Rationale and Design of the CAN Study: an RCT of Survival after Propofol- or Sevoflurane-based Anesthesia for Cancer Surgery

Long-term Survival after Volatile or Propofol General Anesthesia for Bladder Cancer Surgery: A Retrospective National Registry Cohort Study

BACKGROUND

Prospective interventional trials and retrospective observational analyses provide conflicting evidence regarding the relationship between propofol versus inhaled volatile general anesthesia and long-term survival after cancer surgery. Specifically, bladder cancer surgery lacks prospective clinical trial evidence.

METHODS

Data on bladder cancer surgery performed under general anesthesia between 2014 and 2021 from the National Quality Registry for Urinary Tract and Bladder Cancer and the Swedish Perioperative Registry were record-linked. Overall survival was compared between patients receiving propofol or inhaled volatile for anesthesia maintenance. The minimum clinically important difference was defined as a 5-percentage point difference in 5-yr survival.

RESULTS

Of 7,571 subjects, 4,519 (59.7%) received an inhaled volatile anesthetic, and 3,052 (40.3%) received propofol for general anesthesia maintenance. The two groups were quite similar in most respects but differed in American Society of Anesthesiologists Physical Status and tumor stage. Propensity score matching was used to address treatment bias. Survival did not differ during follow-up (median, 45 months [interquartile range, 33 to 62 months]) in the full unmatched cohort nor after 1:1 propensity score matching (3,052 matched pairs). The Kaplan-Meier adjusted 5-yr survival rates in the matched cohort were 898 of 3,052, 67.5% (65.6 to 69.3%) for propofol and 852 of 3,052, 68.5% (66.7 to 70.4%) for inhaled volatile general anesthesia, respectively (hazard ratio, 1.05 [95% CI, 0.96 to 1.15]; P = 0.332). A sensitivity analysis restricted to 1,766 propensity score-matched pairs of patients who received only one general anesthetic during the study period did not demonstrate a difference in survival; Kaplan-Meier adjusted 5-yr survival rates were 521 of 1,766, 67.1% (64.7 to 69.7%) and 482 of 1,766, 68.9% (66.5 to 71.4%) for propofol and inhaled volatile general anesthesia, respectively (hazard ratio, 1.09 [95% CI, 0.97 to 1.23]; P = 0.139).

CONCLUSIONS

Among patients undergoing bladder cancer surgery under general anesthesia, there was no statistically significant difference in long-term overall survival associated with the choice of propofol or an inhaled volatile maintenance.

EDITOR’S PERSPECTIVE

Anesthesia and cancer recurrence: a narrative review

Cancer is a leading cause of death worldwide. With the increasingly aging population, the number of emerging cancer cases is expected to increase markedly in the foreseeable future. Surgical resection with adjuvant therapy is the best available option for the potential cure of many solid tumors; thus, approximately 80% of patients with cancer undergo at least one surgical procedure during their disease. Agents used in general anesthesia can modulate cytokine release, transcription factors, and/or oncogenes. This can affect host immunity and the capability of cancer cells to survive and migrate, not only during surgery but for up to several weeks after surgery. However, it remains unknown whether exposure to anesthetic agents affects cancer recurrence or metastasis. This review explores the current literature to explain whether and how the choice of anesthetic and perioperative medication affect cancer surgery outcomes.

Impact of general anaesthesia on breast cancer survival: a 5-year follow up of a pragmatic, randomised, controlled trial, the CAN-study, comparing propofol and sevoflurane

Background

Anaesthesia may impact long-term cancer survival. In the Cancer and Anaesthesia study, we hypothesised that the hypnotic drug propofol will have an advantage of at least five percentage points in five-year survival over the inhalational anaesthetic sevoflurane for breast cancer surgery.

Methods

From 2118 eligible breast cancer patients scheduled for primary curable, invasive breast cancer surgery, 1764 were recruited after ethical approval and individual informed consent to this open label, single-blind, randomised trial at four county- and three university hospitals in Sweden and one Chinese university hospital. Of surveyed patients, 354 were excluded, mainly due to refusal to participate. Patients were randomised by computer at the monitoring organisation to general anaesthesia maintenance with either intravenous propofol or inhaled sevoflurane in a 1:1 ratio in permuted blocks. Data related to anaesthesia, surgery, oncology, and demographics were registered. The primary endpoint was five-year overall survival. Data are presented as Kaplan-Meier survival curves and Hazard Ratios based on Cox univariable regression analyses by both intention-to-treat and per-protocol. EudraCT, 2013-002380-25 and ClinicalTrials.gov, NCT01975064.

Findings

Of 1764 patients, included from December 3, 2013, to September 29, 2017, 1670 remained for analysis. The numbers who survived at least five years were 773/841 (91.9% (95% CI 90.1-93.8)) in the propofol group and 764/829 (92.2% (90.3-94.0)) in the sevoflurane group, (HR 1.03 (0.73-1.44); P = 0.875); the corresponding results in the per-protocol-analysis were: 733/798 (91.9% (90.0-93.8)) and 653/710 (92.0% (90.0-94.0)) (HR = 1.01 (0.71-1.44); P = 0.955). Survival after a median follow-up of 76.7 months did not indicate any difference between the groups (HR 0.97, 0.72-1.29; P = 0.829, log rank test).

Interpretation

No difference in overall survival was found between general anaesthesia with propofol or sevoflurane for breast cancer surgery.

Funding

Swedish Research Council; Uppsala-Örebro Regional Research Council; Västmanland Regional Research Fund; Västmanland Cancer Foundation; Stig and Ragna Gohrton Foundation; Birgit and Henry Knutsson Foundation.

Volatile versus propofol general anesthesia and long-term survival after breast cancer surgery: a national registry retrospective cohort study

BACKGROUND

Several retrospective studies using administrative or single center data have failed to show any difference between general anesthesia using propofol versus inhaled volatiles on long-term survival after breast cancer surgery. Although randomized controlled trials are ongoing, validated data from national clinical registries may advance the reliability of existing knowledge.

METHODS

Data on breast cancer surgery performed under general anesthesia between 2013 and 2019 from The Swedish PeriOperative Register and The National Quality Register for Breast Cancer were record-linked. Overall survival was compared between patients receiving propofol or inhaled volatile for anesthesia maintenance.

RESULTS

Of 18,674 subjects, 13,873 patients (74.3%) received propofol and 4,801 (25.7%) received an inhaled volatile for general anesthesia maintenance. The two cohorts differed in most respects. Patients receiving inhaled volatile were older (67 years vs 65 years), sicker (888 [19.0%] ASA status 3-5 versus 1,742 [12.8%]), and the breast cancer to be more advanced. Median follow-up was 33 months (IQR, 19 to 48). In the full, unmatched cohort, there was a statistically significantly higher overall survival among patients receiving propofol (13,489/ 13,873 (97.2%)) versus inhaled volatile (4,039/4,801 (84.1%)) hazard ratio = 0.80 (95% CI 0.70-0.90, P < 0.001). Following 1:1 propensity score matching (4,658 matched pairs) there was no statistically significant difference in overall survival, (propofol 4,284/4,658 (92.0%) versus inhaled volatile 4,288/4,658 (92.1%) hazard ratio = 0.98 (95% CI 0.85-1.13, P = 0.756)).

CONCLUSIONS

Among patients undergoing breast cancer surgery under general anesthesia, no association was observed between the choice of propofol or an inhaled volatile maintenance and overall survival.

Effects of Propofol Versus Sevoflurane on Postoperative Breast Cancer Prognosis: A Narrative Review

Perioperative interventions produce substantial biologic perturbations which are associated with the risk of recurrence after cancer surgery. The changes of tumor microenvironment caused by anesthetic drugs received increasing attention. Till now, it’s still unclear whether or not anesthetic drugs may exert positive or negative impact on cancer outcomes after surgery. Breast cancer is the most common tumor and the leading cause of cancer deaths in women. Propofol and sevoflurane are respectively the most commonly used intravenous and inhaled anesthetics. Debates regarding which of the two most commonly used anesthetics may relatively contribute to the recurrence and metastasis vulnerability of breast cancer postoperatively remain. This review aimed to provide a comprehensive view about the effect of propofol versus sevoflurane on the prognosis of breast cancer obtained from pre-clinical studies and clinical studies. Laboratory and animal studies have demonstrated that sevoflurane may enhance the recurrence and metastasis of breast cancer, while propofol is more likely to reduce the activity of breast cancer cells by attenuating the suppression of the immune system, promoting tumor cells apoptosis, and through other direct anti-tumor effects. However, retrospective clinical studies have shown contradictory results about the effects of propofol and sevoflurane on long-term survival in breast cancer patients. Furthermore, recent prospective studies did not identify significant differences between propofol and sevoflurane in breast cancer metastasis and recurrence. Therefore, more preclinical studies and randomized controlled studies are needed to guide the choice of anesthetics for breast cancer patients.

Anesthesia and Cancer, Friend or Foe? A Narrative Review

Cancer remains the leading cause of death worldwide with close to 10 million deaths reported annually. Due to growth of the advanced age cohort in our population, it is predicted that the number of new cancer cases diagnosed between now until 2035 is to reach potentially 24 million individuals, a staggering increase in a relatively short time period. For many solid tumors, surgical resection along with chemotherapy is the best available approach to a potential cure which leads to almost 80% of cancer patients undergoing at least one surgical procedure during the course of their disease. During surgical intervention, the exposure to general anesthesia can be lengthy, complex and often involves various modalities resulting in an important question as to the role, if any, anesthesia may play in primary recurrence or metastatic conversion. Many components of the stress and inflammatory responses exhibited in the perioperative period can contribute to cancer growth and invasion. The agents used to induce and maintain general anesthesia have variable interactions with the immune and neuroendocrine systems and can influence the stress response during surgery. Thus, debating the best type of anesthesia that would help to attenuate sympathetic and/or pro-inflammatory responses while modulating cytokine release and transcription factors/oncogenes remains at the forefront. This may affect inducible cancer cell survival and migratory abilities not only intra-operatively, but also during the immediate post-operative phase of recovery. The ultimate question becomes how and whether the choice of anesthesia may influence the outcomes of cancer surgery with two major approaches being considered, i.e., regional and general anesthesia as well as the various hypnotics, analgesics and sympatholytics commonly used. In this review, we will address the latest information as to the role that anesthesia may play during cancer surgery with specific focus on primary recurrence and metastasis.

Effect of Volatile Anesthetics on Myocardial Infarction After Coronary Artery Surgery: A Post Hoc Analysis of a Randomized Trial

OBJECTIVE

To investigate the effect of volatile anesthetics on the rates of postoperative myocardial infarction (MI) and cardiac death after coronary artery bypass graft (CABG).

DESIGN

A post hoc analysis of a randomized trial.

SETTING

Cardiac surgical operating rooms.

PARTICIPANTS

Patients undergoing elective, isolated CABG.

INTERVENTIONS

Patients were randomized to receive a volatile anesthetic (desflurane, isoflurane, or sevoflurane) or total intravenous anesthesia (TIVA). The primary outcome was hemodynamically relevant MI (MI requiring high-dose inotropic support or prolonged intensive care unit stay) occurring within 48 hours from surgery. The secondary outcome was 1-year death due to cardiac causes.

MEASUREMENTS AND MAIN RESULTS

A total of 5,400 patients were enrolled between April 2014 and September 2017 (2,709 patients randomized to the volatile anesthetics group and 2,691 to TIVA). The mean age was 62 ± 8.4 years, and the median baseline ejection fraction was 57% (50-67), without differences between the 2 groups. Patients in the volatile group had a lower incidence of MI with hemodynamic complications both in the per-protocol (14 of 2,530 [0.6%] v 27 of 2,501 [1.1%] in the TIVA group; p = 0.038) and as-treated analyses (16 of 2,708 [0.6%] v 29 of 2,617 [1.1%] in the TIVA group; p = 0.039), but not in the intention-to-treat analysis (17 of 2,663 [0.6%] v 28 of 2,667 [1.0%] in the TIVA group; p = 0.10). Overall, deaths due to cardiac causes were lower in the volatile group (23 of 2,685 [0.9%] v 40 of 2,668 [1.5%] than in the TIVA group; p = 0.03).

CONCLUSIONS

An anesthetic regimen, including volatile agents, may be associated with a lower rate of postoperative MI with hemodynamic complication in patients undergoing CABG. Furthermore, it may reduce long-term cardiac mortality.

Propofol-based total intravenous anesthesia is associated with better survival than desflurane anesthesia in glioblastoma surgery

Background

Previous research has shown that anesthetic techniques can influence patient outcomes following cancer surgery. However, the effects of anesthesia in patients undergoing glioblastoma surgery are still not known. We studied the relationship between the type of anesthesia and patient outcomes following elective glioblastoma surgery.

Methods

This was a retrospective cohort study of patients who underwent elective glioblastoma surgery between January 2008 and December 2018. Patients were grouped according to the anesthesia they received, desflurane or propofol. A Kaplan-Meier analysis was conducted, and survival curves were presented from the date of surgery to death. Univariable and multivariable Cox regression models were used to compare hazard ratios for death after propensity matching.

Results

A total of 50 patients (45 deaths, 90.0%) under desflurane anesthesia and 53 patients (38 deaths, 72.0%) under propofol anesthesia were included. Thirty-eight patients remained in each group after propensity matching. Propofol anesthesia was associated with improved survival (hazard ratio, 0.51; 95% confidence interval, 0.30–0.85; P = 0.011) in a matched analysis. Furthermore, patients under propofol anesthesia exhibited less postoperative recurrence than those under desflurane anesthesia (hazard ratio, 0.60; 95% confidence interval, 0.37–0.98; P = 0.040) in a matched analysis.

Conclusions

In this limited sample size, we observed that propofol anesthesia was associated with improved survival and less postoperative recurrence in glioblastoma surgery than desflurane anesthesia. Further investigations are needed to examine the influence of propofol anesthesia on patient outcomes following glioblastoma surgery.

Is It Definitely Clear That Long-Term Survival after Breast Cancer Surgery Is Not Affected by Anaesthetics?

Retrospective studies indicate that cancer survival may be affected by the anaesthetic technique. Propofol seems to be a better choice than volatile anaesthetics, such as sevoflurane. The first two retrospective studies suggested better long-term survival with propofol, but not for breast cancer. Subsequent retrospective studies from Asia indicated the same. When data from seven Swedish hospitals were analysed, including 6305 breast cancer patients, different analyses gave different results, from a non-significant difference in survival to a remarkably large difference in favour of propofol, an illustration of the innate weakness in the retrospective design. The largest randomised clinical trial, registered on clinicaltrial.gov, with survival as an outcome is the Cancer and Anesthesia study. Patients are here randomised to propofol or sevoflurane. The inclusion of patients with breast cancer was completed in autumn 2017. Delayed by the pandemic, one-year survival data for the cohort were presented in November 2020. Due to the extremely good short-term survival for breast cancer, one-year survival is of less interest for this disease. As the inclusions took almost five years, there was also a trend to observe. Unsurprisingly, no difference was found in one-year survival between the two groups, and the trend indicated no difference either.

Survival after primary breast cancer surgery following propofol or sevoflurane general anesthesia-A retrospective, multicenter, database analysis of 6305 Swedish patients

BACKGROUND

Retrospective studies indicate that the choice of anesthetic can affect long-term cancer survival. Propofol seems to have an advantage over sevoflurane. However, this is questioned for breast cancer. We gathered a large cohort of breast cancer surgery patients from seven Swedish hospitals and hypothesized that general anesthesia with propofol would be superior to sevoflurane anesthesia regarding long-term breast cancer survival.

METHODS

We identified all patients who were anaesthetized for breast cancer surgery between 2006 and 2012. The patients were matched to the Swedish Breast Cancer Quality Register, to retrieve tumor characteristics, prognostic factors, and adjuvant treatment as well as date of death. Overall survival between patients undergoing sevoflurane and propofol anesthesia was analyzed with different statistical approaches: (a) multiple Cox regression models adjusted for demographic, oncological, and multiple control variables, (b) propensity score matching on the same variables, but also including the participating centers as a cofactor in a separate analysis.

RESULTS

The database analysis identified 6305 patients. The 5-year survival rates were 91.0% and 81.8% for the propofol and sevoflurane group, respectively, in the final model (P = .126). Depending on the statistical adjustment method used, different results were obtained, from a non-significant to a "proposed" and even a "determined" difference in survival that favored propofol, with a maximum of 9.2 percentage points higher survival rate at 5 years (hazard ratio 1.46, 95% CI 1.10-1.95).

CONCLUSIONS

It seems that propofol may have a survival advantage compared with sevoflurane among breast cancer patients, but the inherent weaknesses of retrospective analyses were made apparent.