Halothane potentiates the antitumor activity of gamma-interferon and mimics calmodulin-blocking agents

Anesthesia Medications and Interaction with Chemotherapeutic Agents

Cancer is now a leading health concern worldwide. In an effort to provide these patients with adequate care, coordination between anesthesiologists and surgeons is crucial. In cancer-related treatment, it is very clear that radio-chemotherapy and medical procedures are important. There are some obstacles to anesthesia when dealing with cancer treatment, such as physiological disturbances, tumor-related symptoms, and toxicity in traditional chemotherapy treatment. Therefore, it is important that a multisystemic, multidisciplinary and patient-centered approach is used to preserve perioperative homeostasis and immune function integrity. Adding adjuvants can help increase patient safety and satisfaction and improve clinical efficacy. Correctly paired anesthetic procedures and medications will reduce perioperative inflammatory and immune changes that could potentially contribute to improved results for future cancer patients. Further research into best practice strategies is required which will help to enhance the acute and long-term effects of cancer care in clinical practice.

The Role of Inhaled Anesthetics in Tumorigenesis and Tumor Immunity

Inhaled anesthetics are widely used for induction and maintenance of anesthesia during surgery, including isoflurane, sevoflurane, desflurane, haloflurane, nitrous oxide (N₂O), enflurane and xenon. Nowadays, it is controversial whether inhaled anesthetics may influence the tumor progression, which urges us to describe the roles of different inhaled anesthetics in human cancers. In the review, the relationships among the diverse inhaled anesthetics and patient outcomes, immune response and cancer cell biology were discussed. Moreover, the mechanisms of various inhaled anesthetics in the promotion or inhibition of carcinogenesis were also reviewed. In summary, we concluded that several inhaled anesthetics have different immune functions, clinical outcomes and cancer cell biology, which could contribute to opening new avenues for selecting suitable inhaled anesthetics in cancer surgery.

Anaesthesia and anti-cancer chemotherapeutic drugs

PURPOSE OF REVIEW

This is a review of anti-cancer chemotherapeutic drugs, describing their actions, interactions, and toxicity with a particular focus on the relevance for the anaesthetist.

RECENT FINDINGS

Anti-cancer chemotherapeutics have a vast array of adverse effects, some of which, i.e. cardiac and pulmonary toxicity, are of particular anaesthesiological relevance. Recently it has been shown that following chemotherapy with anthracyclines subtle abnormalities in cardiac function may exist even in those patients with a normal resting cardiac function, which become apparent only during anaesthesia or exercise. Children and adolescents with previous anthracycline treatment and normal cardiac function at rest had a significantly greater decrease in fractional shortening, a marker of left-ventricular systolic function, and stroke-volume index during a balanced anaesthesia with isoflurane [1 minimum alveolar concentration (MAC)] in N2O/O2. Notably, delayed cardiotoxicity (years after completed chemotherapy) has been seen only after anthracycline therapy. With respect to regional anaesthetics, one should be aware that in a considerable percentage of patients a sub-clinical, unrecognized neuropathy may be present in patients with previous chemotherapy, particularly after cisplatin treatment. Recently, a diffuse brachial plexopathy after interscalene blockade has been reported in a patient receiving cisplatin chemotherapy. Thus, if regional anaesthesia is contemplated, a detailed pre-operative neurological examination and careful assessment of the risks and benefits is warranted.

SUMMARY

Anti-cancer chemotherapeutic drugs may cause generalized and specific organ toxicities and may also give rise to various unpredictable or life-threatening peri-operative complications, rendering a detailed pre-operative assessment of patients with previous chemotherapy mandatory.

Effect of halothane on intercellular adhesion molecule-1 (ICAM-1) in melanoma cells

There have only been a few reports relating to the effect of inhalational anesthetics on the tumor cell morphology in cancer patients undergoing surgery. We hypothesized that some anesthetic agents might influence the spread of unresectable cancer cells and might additionally worsen the condition of the patient due to depressed host immune surveillance. We therefore evaluated the influence of halothane on tumor cell adhesion, which is closely linked to tumor cell metastasis. Human melanoma cells from SK-MEL-37 cell-line were exposed to 4% halothane for 3, 6, 12 or 24 hours, respectively. Furthermore, after 24 hours halothane exposure, they were incubated in a 5% CO2 atmosphere for 12 or 24 hours. The cells were then analyzed using a fluorescence flowcytometer and intercellular adhesion molecule-1 (ICAM-1) expression in SK-MEL-37 cells was quantified as the intensity of fluorescence of ICAM-1 expressed in 10,000 cells. ICAM-1 expression in cells exposed to halothane for 3, 6, 12 or 24 hours was lower than that of non-exposed cells and returned to control level after further incubation in 5% CO2 atmosphere for either 12 or 24 hours. We conclude that halothane might affect the progression of tumor cell metastasis in vitro.

Anaesthetic implications of anticancer chemotherapy

In anaesthetic practice we deal with cancer patients who are scheduled for operations on tumours or other manifestations of malignant disease. Those patients are often debilitated and have significant weight loss accompanied with hypoproteinaemia, anaemia and coagulation disorders. Oncological patients usually present to the anaesthetist before tumour disease surgery, but they are also candidates for elective operations (e.g. hernia repair) and urgent/emergency surgery (e.g. trauma, fractures and ileus). Chemotherapeutic agents given to these patients are potentially noxious, can affect the conduct of anaesthesia and, furthermore, may aggravate the patient's condition. In this review the most commonly used cytostatic drug regimens and their common side-effects are listed. Some preclinical studies on anaesthetic and cytostatic drug metabolism and interactions are emphasized, as well as clinically relevant perioperative alterations that may affect anaesthetic management in cancer patients. An anaesthetist may have to modify a routine anaesthetic regimen in cancer patients especially if anticancer chemotherapeutics were given. Clinically silent toxic drug effects may become apparent during operation, trauma or in the early postoperative course in such patients. Altered reactions to commonly used anaesthetics in patients receiving chemotherapeutics and an impaired stress reaction may occur in such patients. Special attention must be drawn to protection against opportunistic infections.

[Effects of anesthetic agents on arterial reactivity]

OBJECTIVE

To review the effects of halogenated and intravenous anaesthetics on arterial vasoreactivity.

DATA SOURCE

Articles were obtained from a MEDLINE review (search terms: 'vascular smooth muscle, endothelium' used separately or associated with following anaesthetic agents: 'halothane, isoflurane, enflurane, desflurane, sevoflurane, thiopentone, propofol, ketamine, etomidate'. Other sources included review articles and textbooks.

STUDY SELECTION AND DATA EXTRACTION

All experimental studies published since 1975 were analysed and pertinent data extracted.

DATA SYNTHESIS

Within the vascular wall, arterial vasoreactivity involves the endothelium and the vascular smooth muscle. In vivo, arterial vasoreactivity is regulated by neuronal, hormonal, and metabolic factors. In vitro, the direct action of anaesthetic agents on the vessel can be studied in the absence of such factors. In vitro studies with arterial rings have shown that inhalational anaesthetics directly decrease endothelium-independent contraction induced by various pharmacological agents. This direct effect of anaesthetics results from a decrease in intracellular calcium, mainly caused by an inhibition of transsarcoplasmic calcium influx. Volatile anaesthetics decrease endothelium-dependent vasorelaxation at a site(s) within the nitric oxide (NO) signalling pathway, located downstream from the NO-related receptors and upstream from guanylyl cyclase. They may also decrease endothelium-independent vasorelaxation by inhibiting NO activation of guanylate cyclase. Intravenous anaesthetics, such as propofol, barbiturates, ketamine and etomidate also decrease vasoconstriction by various degrees. Propofol is the most potent inhibitor of vasoconstriction and thiopental the least one. All these IV anaesthetics have been shown to inhibit in some circumstances both endothelium-dependent and -independent vasorelaxation. Further studies are required to enable a better understanding of the mechanism and the site of action of these vascular effects of anaesthetics. For example, the investigation of the effects of anaesthetic agents on vascular reactivity in diseases associated with endothelial dysfunction may indirectly provide insight into the role of endothelium.