Long-term survival in older patients given propofol or sevoflurane anaesthesia for major cancer surgery: follow-up of a multicentre randomised trial

The Role of GABA Receptors in Anesthesia and Sedation: An Updated Review

GABA (γ-aminobutyric acid) receptors are constituents of many inhibitory synapses within the central nervous system. They are formed by 5 subunits out of 19 various subunits: α1-6, β1-3, γ1-3, δ, ε, θ, π, and ρ1-3. Two main subtypes of GABA receptors have been identified, namely GABAA and GABAB. The GABAA receptor (GABAAR) is formed by a variety of combinations of five subunits, although both α and β subunits must be included to produce a GABA-gated ion channel. Other subunits are γ, δ, ε, π, and ϴ. GABAAR has many isoforms, that dictate, among other properties, their differing affinities and conductance. Drugs acting on GABAAR form the cornerstone of anesthesia and sedation practice. Some such GABAAR agonists used in anesthesia practice are propofol, etomidate, methohexital, thiopental, isoflurane, sevoflurane, and desflurane. Ketamine, nitrous oxide, and xenon are not GABAR agonists and instead inhibit glutamate receptors-mainly NMDA receptors. Inspite of its many drawbacks such as pain in injection, quick and uncontrolled conversion from sedation to general anesthesia and dose-related cardiovascular depression, propofol remains the most popular GABAR agonist employed by anesthesia providers. In addition, being formulated in a lipid emulsion, contamination and bacterial growth is possible. Literature is rife with newer propofol formulations, aiming to address many of these drawbacks, and with some degree of success. A nonemulsion propofol formulation has been developed with cyclodextrins, which form inclusion complexes with drugs having lipophilic properties while maintaining aqueous solubility. Inhalational anesthetics are also GABA agonists. The binding sites are primarily located within α+/β- and β+/α- subunit interfaces, with residues in the α+/γ- interface. Isoflurane and sevoflurane might have slightly different binding sites providing unexpected degree of selectivity. Methoxyflurane has made a comeback in Europe for rapid provision of analgesia in the emergency departments. Penthrox (Galen, UK) is the special device designed for its administration. With better understanding of pharmacology of GABAAR agonists, newer sedative agents have been developed, which utilize "soft pharmacology," a term pertaining to agents that are rapidly metabolized into inactive metabolites after producing desired therapeutic effect(s). These newer "soft" GABAAR agonists have many properties of ideal sedative agents, as they can offer well-controlled, titratable activity and ultrashort action. Remimazolam, a modified midazolam and methoxycarbonyl-etomidate (MOC-etomidate), an ultrashort-acting etomidate analog are two such examples. Cyclopropyl methoxycarbonyl metomidate is another second-generation soft etomidate analog that has a greater potency and longer half-life than MOC-etomidate. Additionally, it might not cause adrenal axis suppression. Carboetomidate is another soft analog of etomidate with low affinity for 11β-hydroxylase and is, therefore, unlikely to have clinically significant adrenocortical suppressant effects. Alphaxalone, a GABAAR agonist, is recently formulated in combination with 7-sulfobutylether-β-cyclodextrin (SBECD), which has a low hypersensitivity profile.

Anesthetic Techniques and Cancer Outcomes: What Is the Current Evidence?

It is almost 2 decades since it was first hypothesized that anesthesia technique might modulate cancer biology and thus potentially influence patients' long-term outcomes after cancer surgery. Since then, research efforts have been directed towards elucidating the potential pharmacological and physiological basis for the effects of anesthetic and perioperative interventions on cancer cell biology. In this review, we summarize current laboratory and clinical data. Taken together, preclinical studies suggest some biologic plausibility that cancer cell function could be influenced. However, available clinical evidence suggests a neutral effect. Observational studies examining cancer outcomes after surgery of curative intent for many cancer types under a variety of anesthetic techniques have reported conflicting results, but warranting prospective randomized clinical trials (RCTs). Given the large patient numbers and long follow-up times required for adequate power, relatively few such RCTs have been completed to date. With the sole exception of peritumoral lidocaine infiltration in breast cancer surgery, these RCTs have indicated a neutral effect of anesthetic technique on long-term oncologic outcomes. Therefore, unless there are significant new findings from a few ongoing trials, future investigation of how perioperative agents interact with tumor genes that influence metastatic potential may be justified. In addition, building multidisciplinary collaboration to optimize perioperative care of cancer patients will be important.

Intraoperative hypotension is associated with decreased long-term survival in older patients after major noncardiac surgery: Secondary analysis of three randomized trials

STUDY OBJECTIVE

To assess the association of intraoperative hypotension with long-term survivals in older patients after major noncardiac surgery mainly for cancer.

DESIGN

A secondary analysis of databases from three randomized trials with long-term follow-up.

SETTING

The underlying trials were conducted in 17 tertiary hospitals in China.

PATIENTS

Patients aged 60 to 90 years who underwent major noncardiac thoracic or abdominal surgeries (≥ 2 h) in a single center were included in this analysis.

EXPOSURES

Restricted cubic spline models were employed to determine the lowest mean arterial pressure (MAP) threshold that was potentially harmful for long-term survivals. Patients were arbitrarily divided into three groups according to the cumulative duration or area under the MAP threshold. The association between intraoperative hypotension exposure and long-term survivals were analyzed with the Cox proportional hazard regression models.

MEASUREMENTS

Our primary endpoint was overall survival. Secondary endpoints included recurrence-free and event-free survivals.

MAIN RESULTS

A total of 2664 patients (mean age 69.0 years, 34.9% female sex, 92.5% cancer surgery) were included in the final analysis. MAP < 60 mmHg was adopted as the threshold of intraoperative hypotension. Patients were divided into three groups according to duration under MAP < 60 mmHg (<1 min, 1-10 min, and > 10 min) or area under MAP <60 mmHg (< 1 mmHg⋅min, 1-30 mmHg⋅min, and > 30 mmHg⋅min). After adjusting confounders, duration under MAP < 60 mmHg for > 10 min was associated with a shortened overall survival when compared with the < 1 min patients (adjusted hazard ratio [HR] 1.31, 95% confidence interval [CI] 1.09 to 1.57, P = 0.004); area under MAP < 60 mmHg for > 30 mmHg⋅min was associated with a shortened overall survival when compared with the < 1 mmHg⋅min patients (adjusted HR 1.40, 95% CI 1.16 to 1.68, P < 0.001). Similar associations exist between duration under MAP < 60 mmHg for > 10 min or area under MAP < 60 mmHg for > 30 mmHg⋅min and recurrence-free or event-free survivals.

CONCLUSIONS

In older patients who underwent major noncardiac surgery mainly for cancer, intraoperative hypotension was associated with worse overall, recurrence-free, and event-free survivals.

The role of perioperative factors in the prognosis of cancer patients: A coin has two sides

Cancer, the second leading cause of mortality globally, poses a significant health challenge. The conventional treatment for solid tumors involves surgical intervention, followed by chemo- and radio-therapies as well as target therapies, but the recurrence and metastasis of cancers remain a major issue. Anesthesia is essential for ensuring patient comfort and safety during surgical procedures. Despite its crucial role during the surgery, the precise effect of anesthesia on cancer patient outcomes is not clearly understood. This comprehensive review aims to elucidate the various anesthesia strategies used in the perioperative care of cancer patients and their potential effects on patients' prognosis, but understanding the complex relationship between anesthesia and cancer outcomes is crucial, given the complexity in cancer treaments. Examining potential implications of anesthesia strategies on cancer patient prognosis may help better understand treatment efficacy and risk factors of cancer recurrence and metastasis. Through a detailed analysis of anesthesia practices in cancer surgery, this review aims to provide insights that may lead to improving the existing anesthesia protocols and ultimately reduce risk factors for patient outcomes in the field of oncology.

Perioperative Immunosuppressive Factors during Cancer Surgery: An Updated Review

Surgical excision of the primary tumor represents the most frequent and curative procedure for solid malignancies. Compelling evidence suggests that, despite its beneficial effects, surgery may impair immunosurveillance by triggering an immunosuppressive inflammatory stress response and favor recurrence by stimulating minimal residual disease. In addition, many factors interfere with the immune effectors before and after cancer procedures, such as malnutrition, anemia, or subsequent transfusion. Thus, the perioperative period plays a key role in determining oncological outcomes and represents a short phase to circumvent anesthetic and surgical deleterious factors by supporting the immune system through the use of synergistic pharmacological and non-pharmacological approaches. In line with this, accumulating studies indicate that anesthetic agents could drive both protumor or antitumor signaling pathways during or after cancer surgery. While preclinical investigations focusing on anesthetics' impact on the behavior of cancer cells are quite convincing, limited clinical trials studying the consequences on survival and recurrences remain inconclusive. Herein, we highlight the main factors occurring during the perioperative period of cancer surgery and their potential impact on immunomodulation and cancer progression. We also discuss patient management prior to and during surgery, taking into consideration the latest advances in the literature.

Uncovering essential anesthetics-induced exosomal miRNAs related to hepatocellular carcinoma progression: a bioinformatic investigation

BACKGROUND

Anesthetic drugs may alter exosomal microRNA (miRNA) contents and mediate cancer progression and tumor microenvironment remodeling. Our study aims to explore how the anesthetics (sevoflurane and propofol) impact the miRNA makeup within exosomes in hepatocellular carcinoma (HCC), alongside the interconnected signaling pathways linked to the tumor immune microenvironment.

METHODS

In this prospective study, we collected plasma exosomes from two groups of HCC patients (n = 5 each) treated with either propofol or sevoflurane, both before anesthesia and after hepatectomy. Exosomal miRNA profiles were assessed using next-generation sequencing (NGS). Furthermore, the expression data from The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) was used to pinpoint the differentially expressed exosomal miRNAs (DEmiRNAs) attributed to the influence of propofol or sevoflurane in the context of HCC. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were used to dissect the signaling pathways and biological activities associated with the identified DEmiRNAs and their corresponding target genes.

RESULTS

A total of 35 distinct DEmiRNAs were exclusively regulated by either propofol (n = 9) or sevoflurane (n = 26). Through TCGA-LIHC database analysis, 8 DEmiRNAs were associated with HCC. These included propofol-triggered miR-452-5p and let-7c-5p, as well as sevoflurane-induced miR-24-1-5p, miR-122-5p, miR-200a-3p, miR-4686, miR-214-3p, and miR-511-5p. Analyses revealed that among these 8 DEmiRNAs, the upregulation of miR-24-1-5p consistently demonstrated a significant association with lower histological grades (p < 0.0001), early-stage tumors (p < 0.05) and higher survival (p = 0.029). Further analyses using GSEA and GSVA indicated that miR-24-1-5p, along with its target genes, were involved in governing the tumor immune microenvironment and potentially inhibiting tumor progression in HCC.

CONCLUSIONS

This study provided bioinformatics evidence suggesting that sevoflurane-induced plasma exosomal miRNAs may have a potential impact on the immune microenvironment of HCC. These findings established a foundation for future research into mechanistic outcomes in cancer patients.

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

Effects of anesthesia on long-term survival in cancer surgery: A systematic review and meta-analysis

Backgrounds

The association between anesthesia and long-term oncological outcome after cancer surgery remains controversial. This study aimed to investigate the effect of propofol-based anesthesia and inhalation anesthesia on long-term survival in cancer surgery.

Methods

A comprehensive literature search was performed in PubMed, Medline, Embase, and the Cochrane Library until November 15, 2023. The outcomes included overall survival (OS) and recurrence-free survival (RFS). The hazard ratio (HR) and 95 % confidence interval (CI) were calculated with a random-effects model.

Results

We included forty-two retrospective cohort studies and two randomized controlled trials (RCTs) with 686,923 patients. Propofol-based anesthesia was associated with improved OS (HR = 0.82, 95 % CI:0.76-0.88, P < 0.00001) and RFS (HR = 0.80, 95 % CI:0.73-0.88, P < 0.00001) than inhalation anesthesia after cancer surgery. However, these positive results were only observed in single-center studies (OS: HR = 0.76, 95 % CI:0.68-0.84, P < 0.00001; RFS: HR = 0.76, 95 % CI:0.66-0.87, P < 0.0001), but not in multicenter studies (OS: HR = 0.98, 95 % CI:0.94-1.03, P = 0.51; RFS: HR = 0.95, 95 % CI:0.87-1.04, P = 0.26). The subgroup analysis revealed that propofol-based anesthesia provided OS and RFS advantages in hepatobiliary cancer (OS: HR = 0.58, 95 % CI:0.40-0.86, P = 0.005; RFS: HR = 0.62, 95 % CI:0.44-0.86, P = 0.005), gynecological cancer (OS: HR = 0.52, 95 % CI:0.33-0.81, P = 0.004; RFS: HR = 0.51, 95 % CI:0.36-0.72, P = 0.0001), and osteosarcoma (OS: HR = 0.30, 95 % CI:0.11-0.81, P = 0.02; RFS: HR = 0.32, 95 % CI:0.14-0.75, P = 0.008) surgeries.

Conclusion

Propofol-based anesthesia may be associated with improved OS and RFS than inhalation anesthesia in some cancer surgeries. Considering the inherent weaknesses of retrospective designs and the strong publication bias, our findings should be interpreted with caution. Well-designed multicenter RCTs are still urgent to further confirm these findings.

On the horns of a dilemma: choosing total intravenous anaesthesia or volatile anaesthesia for cancer surgery, an enduring controversy

Two methods for administering general anaesthesia are widely used: propofol-based total intravenous anaesthesia (propofol-TIVA) and inhalation volatile agent-based anaesthesia. Both modalities, which have been standards of care for several decades, boast a robust safety profile. Nevertheless, the potential differential effects of these anaesthetic techniques on immediate, intermediate, and extended postoperative outcomes remain a subject of inquiry. We discuss a recently published longitudinal analysis stemming from a multicentre randomised controlled trial comparing sevoflurane-based inhalation anaesthesia with propofol-TIVA in older patients with cancer, which showed a reduced incidence of emergence and postoperative delirium, comparable postoperative complication rates within 30 days after surgery, and comparable long-term survival rates. We undertake an assessment of the trial's methodological strengths and limitations, contextualise its results within the broader scientific evidence, and explore avenues for resolving the extant controversies in anaesthetic choice for cancer surgery. We aim to pave the way for the incorporation of precision medicine paradigms into the evolving landscape of perioperative care for patients with cancer.

The involvement of the gut microbiota in postoperative cognitive dysfunction based on integrated metagenomic and metabolomics analysis

IMPORTANCE

As the population ages and medical technology advances, anesthesia procedures for elderly patients are becoming more common, leading to an increased prevalence of postoperative cognitive dysfunction. However, the etiology and correlation between the gut microbiota and cognitive dysfunction are poorly understood, and research in this area is limited. In this study, mice with postoperative cognitive dysfunction were found to have reduced levels of fatty acid production and anti-inflammatory flora in the gut, and Bacteroides was associated with increased depression, leading to cognitive dysfunction and depression. Furthermore, more specific microbial species were identified in the disease model, suggesting that modulation of host metabolism through gut microbes may be a potential avenue for preventing postoperative cognitive dysfunction.

Tumour excisional surgery, anaesthetic-analgesic techniques, and oncologic outcomes: a narrative review

Cancer is a growing global burden; there were an estimated 18 million new cancer diagnoses worldwide in 2020. Excisional surgery remains one of the main treatments for solid organ tumours in cancer patients and is potentially curative. Cancer- and surgery-induced inflammatory processes can facilitate residual tumour cell survival, growth, and subsequent recurrence. However, it has been hypothesised that anaesthetic and analgesic techniques during surgery might influence the risk of cancer recurrence. This narrative review aims to provide an updated summary of recent observational studies and new randomised controlled clinical trials on whether certain specific anaesthetic and analgesic techniques or perioperative interventions during tumour resection surgery of curative intent materially affect long-term oncologic outcomes.

Intraoperative blood pressure: could less be more?

Retrospective observational studies have reported a significant association between intraoperative hypotension and postoperative morbidity. However, association does not imply causation, and whether preventing intraoperative hypotension can improve patient outcome remains to be demonstrated. In this issue of the British Journal of Anaesthesia, D'Amico and colleagues meta-analysed 10 prospective randomised trials comparing low (≤60 mm Hg) and higher mean arterial pressure targets during anaesthesia and surgery. They did not observe an increase in postoperative morbidity and mortality in the low target group. In contrast, they reported a statistically significant (but not clinically relevant) reduction in postoperative cardiac arrhythmia and hospital length of stay when targeting mean arterial pressure ≤60 mm Hg. These findings suggest that during most surgical cases, intraoperative hypotension is a marker of the severity, frailty, or both rather than a mediator of postoperative complications.

Delirium in older patients given propofol or sevoflurane anaesthesia for major cancer surgery: a multicentre randomised trial

BACKGROUND

Delirium is a common and disturbing postoperative complication that might be ameliorated by propofol-based anaesthesia. We therefore tested the primary hypothesis that there is less delirium after propofol-based than after sevoflurane-based anaesthesia within 7 days of major cancer surgery.

METHODS

This multicentre randomised trial was conducted in 14 tertiary care hospitals in China. Patients aged 65-90 yr undergoing major cancer surgery were randomised to either propofol-based anaesthesia or to sevoflurane-based anaesthesia. The primary endpoint was the incidence of delirium within 7 postoperative days.

RESULTS

A total of 1228 subjects were enrolled and randomised, with 1195 subjects included in the modified intention-to-treat analysis (mean age 71 yr; 422 [35%] women); one subject died before delirium assessment. Delirium occurred in 8.4% (50/597) of subjects given propofol-based anaesthesia vs 12.4% (74/597) of subjects given sevoflurane-based anaesthesia (relative risk 0.68 [95% confidence interval {CI}: 0.48-0.95]; P=0.023; adjusted relative risk 0.59 [95% CI: 0.39-0.90]; P=0.014). Delirium reduction mainly occurred on the first day after surgery, with a prevalence of 5.4% (32/597) with propofol anaesthesia vs 10.7% (64/597) with sevoflurane anaesthesia (relative risk 0.50 [95% CI: 0.33-0.75]; P=0.001). Secondary endpoints, including ICU admission, postoperative duration of hospitalisation, major complications within 30 days, cognitive function at 30 days and 3 yr, and safety outcomes, did not differ significantly between groups.

CONCLUSIONS

Delirium was a third less common after propofol than sevoflurane anaesthesia in older patients having major cancer surgery. Clinicians might therefore reasonably select propofol-based anaesthesia in patients at high risk of postoperative delirium.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR-IPR-15006209) and ClinicalTrials.gov (NCT02662257).