2. Patient Factors: Hyperglycemia and Obesity
2.1. Hyperglycemia
Diabetes mellitus (DM) and PC are intimately related, as high blood glucose levels promote PC proliferation, invasion, EMT, and metastasis
[13,14][13][14]. In addition, insulin resistance, hyperinsulinemia, hyperglycemia, and chronic inflammation are the mechanisms of type-2-DM-associated PC
[15].
2.1.1. Laboratory Studies
Recently, Otto et al. attributed a role to the type-2-DM-related hyperglycemic inflammatory micromilieu in the acquisition of malignancy-associated alterations in premalignant pancreatic ductal epithelial cells, thus providing new insights into how hyperglycemia might promote PC initiation
[16]. It is well-known that EMT of pancreatic ductal epithelial cells develops in correlation with hyperglycemia or macrophages
[17,18][17][18]. Moreover, hyperglycemia aggravates microenvironment hypoxia, accelerates EMT, and then promotes the metastatic ability of PC. PC is generally hypoxic due to its avascular morphology, and PC cells express high levels of HIF-1α and MMP-9 for promoting tumor growth, invasion and metastasis in a hypoxic environment
[19]. In addition, the accumulation of HIF-1α induced by hyperglycemia might promote pancreatic glycolysis to facilitate cancer progression
[20]. Zhou et al. reported that the high-glucose microenvironment accelerated PC growth
[21]. With regard to the VAs, Guo et al. reported that isoflurane promoted glucose metabolism through upregulation of
miR-21 and suppressed mitochondrial oxidative phosphorylation in ovarian cancer cells
[22]. Dong et al. reported that dezocine, an opioid analgesic, promoted glucose metabolism and impaired the proliferation of lung cancer cells
[23]. However, Codd et al. reported that opioid agonists did not elevate blood glucose and lacked an insulin-reducing effect
[24]. Han et al. reported that indometacin, an inhibitor of cyclooxygenase (COX)-2, ameliorated high-glucose-induced proliferation and invasion via upregulation of E-cadherin in PC cells
[25]. Current laboratory data on the effect of anesthesia on glucose metabolism in PC are limited, and further investigation is required.
2.1.2. Clinical Studies
Insulin resistance, hyperinsulinemia, hyperglycemia, and chronic inflammation are the mechanisms of type-2-DM-associated PC
[15]. Recently, type 2 DM was shown to reduce the likelihood of cancer survival, and was significantly correlated with comorbidity and poor prognosis in patients undergoing PC surgery
[15]. In addition, metformin may lower the probability of PC. By contrast, insulin therapy may amplify the probability of PC
[15]. In another study, approximately 85% of PC patients exhibited impaired glucose tolerance associated with DM and had a reduced overall survival rate
[26]. Elderly patients with new-onset DM are at higher risk of developing PC than the general population
[26]. Therefore, new-onset DM and hyperglycemia serve as important screening tools to diagnose asymptomatic PC and improve PC survival
[26]. Sandini et al. reported that preoperative blood glucose ≥ 140 mg/dL was associated with poor long-term outcomes in patients undergoing resection for PC
[27]. Conti et al. reported that anti-diabetic drugs represented a significant protective factor against mortality among older adults with metastatic PC
[28]. However, in a recent meta-analysis study, blood glucose, fasting blood glucose, and glycated hemoglobin (HbA1c) levels were not associated with the survival of patients with PC
[29].
Liu et al. reported that the blood glucose levels of the DM patients in the propofol group were significantly lower than those in the sevoflurane group during gastric cancer surgery. This result indicated that the effect of propofol on glucose metabolism under surgical stimulation was less than that of sevoflurane
[30]. Epidural blockade with bupivacaine attenuated the hyperglycemic response to surgery by modifying glucose production in colorectal surgery
[31]. Current clinical data on the effect of anesthesia on glucose metabolism in PC are limited. Further investigation is required to determine the effects of anesthetics and analgesics on glucose metabolism in PC (
Figure 1).
Figure 1.
Anesthesia in pancreatic microenvironments.
2.2. Obesity
Obesity-associated adipose tissue inflammation may play a central role in the development of PC and the promotion of PC growth
[32]. Chronic inflammation, hormonal effects, circulating adipokines, and adipocyte-mediated inflammatory and immunosuppressive microenvironments are involved in the association of obesity with PC
[33]. The tumor-promoting effects of obesity occur at the local level via adipose inflammation and associated alterations in the microenvironment, as well as systemically via circulating metabolic and inflammatory mediators associated with adipose inflammation
[34].
In a review article, Heil et al. reported that anesthetics with the effect of inhibiting obesity-induced inflammation may improve postoperative outcomes
[35]. Eley et al. concluded that VAs, ketamine, opioids, propofol, and regional anesthesia have been shown to modulate parts of the immune system in patients with obesity
[36].
2.2.1. Laboratory Study
Incio et al. reported that obesity-induced inflammation and desmoplasia promoted PC progression and resistance to chemotherapy
[37]. Until now, there have been no laboratory studies on the effects of anesthetics in obesity-induced inflammation and PC progression, and further investigation is necessary.
2.2.2. Clinical Studies
Recently, Zorbas et al. showed that obesity was significantly associated with higher risk of postoperative complications and mortality in patients with body mass index ≥ 40 after pancreatoduodenectomy
[38]. Li et al. reported that the lean body-weight-based dosing of propofol had more potent antioxidant and anti-inflammatory effects on morbidly obese patients than the total body-weight-based dosing during anesthesia induction
[39]. Until now, there have been no clinical studies on the effects of anesthetics in obesity-induced inflammation and PC progression, and further investigation is necessary.
3. Tumor Factors: EMT, Hypoxia-Inducible Factor-1α (HIF-1α), Matrix Metalloproteinases (MMP)-9 Expression, Inflammation, Apoptosis, Autophagy, and Oxidative Stress
3.1. EMT
The development of EMT originates in the conversion of epithelial cells to motile mesenchymal stem cells
[40], which is based on many essential processes involving embryonic progression, tissue formation/fibrosis, and wound repairing
[40]. Moreover, the initiation of EMT contributes to tumor growth, therapy resistance, and tumor spreading
[40]. In the case of high EMT expression in tumors, deterioration of overall outcomes and metastases is inevitable.
[40,41,42,43][40][41][42][43]. However, research on the direct effects of specific anesthetics on EMT of PC is currently lacking, and further investigation is required.
3.1.1. Laboratory Studies
Anesthesia and analgesia may affect EMT
[25,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61][25][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61]. Studies have reported that propofol suppressed EMT in esophageal cancer, choriocarcinoma, breast cancer, thyroid cancer, lung cancer, gastric cancer, hepatocellular carcinoma (HCC), renal cell carcinoma (RCC), prostate cancer, and oral squamous cell carcinoma cells
[45,46,47,48,49,50,51,52,53,54][45][46][47][48][49][50][51][52][53][54]. By contrast, Ren et al. reported that desflurane induced EMT and metastasis in colorectal cancer through deregulation of the miR-34a/LOXL3 axis
[44]. Opioids promoted EMT in breast and lung cancers via mu- or delta-opioid receptors
[55,56][55][56]. Zhang et al. showed morphine-induced EMT in esophageal carcinoma cells
[57]. However, sufentanil inhibited EMT by acting on NF-κB and Snail signaling pathways to inhibit proliferation and metastasis of esophageal cancer
[58]. Lidocaine suppressed EMT in ovarian cancer cells
[59]. However, high concentrations of levobupivacaine significantly increased EMT in the A549 lung cancer cell line, and enhanced metastasis in mice
[60]. COX-2 inhibitors may suppress EMT in oral squamous cell carcinoma
[61]. Han et al. reported that indometacin reduced the expression levels of MMP-2, MMP-9, and vascular endothelial growth factor (VEGF) by upregulation of E-cadherin, inhibiting proliferation and invasion of PC
[25]. Zheng et al. observed the benefit of EMT inhibition due to the use of chemotherapy in PC treatment
[62]. To the best of
ouresearcher
s' knowledge, NSAIDs may inhibit EMT expression in PC. Propofol may inhibit EMT, but VAs may promote EMT in different cancers. On the other hand, opioids and LAs may induce uncertain effects (both positive and negative) on EMT. Laboratory research on the direct effects of specific anesthetics on EMT in PC is currently lacking. Further investigation is needed (see existing studies in
Table 1 and
Figure 1).
Table 1.
The existing studies on the effects of anesthetics/analgesics on clinical outcomes and pancreatic microenvironments.
Type of Anesthetics/Analgesics |
Effects |
Clinical studies
Propofol/VAs |
Propofol was associated with no or low-grade complication compared with desflurane in PC surgery [10]; propofol anesthesia was associated with better survival than desflurane anesthesia in PC surgery [11]. |
NSAIDs |
In a systematic review of observational studies, there was no signification association between aspirin use and mortality risk in PC [63]; aspirin use reduced risk of PC [64]; aspirin was associated with improved overall survival and improved disease-free survival in PC surgery [65]. |
Opioids |
High opioid consumption was related to decreased survival rates in newly diagnosed stage IV PC patients [66]; opioid prescription was associated with poor overall survival among PC patients [67]; there was an insignificant relationship between intraoperative opioid use and decreased survival in PC surgery [68]; administration of opioids was associated with prolonged survival in older adult patients with PC [69]. |
LAs |
Intraoperative administration of intravenous lidocaine was associated with improvement of overall survival in PC patients [12]; intraoperatively epidural ropivacaine infusion was associated with survival improvement in PC patients [70]; perioperative lidocaine administration might be beneficial to the function of NK cells in PC surgery [71]; peridural anesthesia with ropivacaine might improve the oncological outcome of PC patients [72]. |
Experimental studies
Propofol |
Propofol attenuated malignant potential by inhibiting HIF-1α and VEGF expression [73]; PC cell growth was inhibited by propofol via suppression of MMP-9 expression [74]; propofol inhibited migration and induced apoptosis [75]; propofol induced apoptosis in PC cells in vitro [76]; propofol inhibited PC progression by downregulating ADAM8 [77,78,79][77][78][79]; propofol suppressed proliferation and invasion of PC cells by upregulating microRNA-133a expression [80]; propofol inhibited growth and invasion of PC cells through regulation of the miR-21/Slug signaling pathway [81]. |
NSAIDs |
Indometacin ameliorated high glucose-induced proliferation and invasion by upregulating E-cadherin (EMT) in PC cells [25]; aspirin counteracted PC stem cell features and desmoplasia and gemcitabine resistance [82]; COX-2 inhibition promoted an immune-stimulatory microenvironment in preclinical models of PC [83]; sodium salicylate inhibited proliferation and induced G1 cell cycle arrest in human PC cell lines [84]; indometacin inhibited proliferation and activation of pancreatic stellate cells through the downregulation of COX-2 [85]. |
Opioids |
Fentanyl decreased gene expression of PC stem cell markers and increased expression of apoptosis-related genes [86]. |
LAs |
High concentrations of ropivacaine or bupivacaine revealed antiproliferative potency in PC cells [87]. |
Midazolam |
Midazolam exhibited antitumor (anti-proliferation) and anti-inflammatory effects in a mouse model of PC [88]. |
Ketamine |
Ketamine significantly inhibited proliferation in PC cells [89]; ketamine significantly inhibited proliferation and apoptosis in PC cells [90]. |