What is the relationship between INHALATION ANESTHESIA and CANCER? - NAVE Discussion

Hello NAVE Crew, how are you? Every now and then someone mentions that inhalation anesthesia predisposes to the development of cancer. Perhaps this (crazy) idea has been spread because there is a history that inhalation anesthetics are related to chronic diseases, teratogenicity, and mutagenicity.

Well, there are several studies showing that professionals working in the surgical team have a high degree of irritability, headache, and miscarriage when compared to those who do not work in the operating room. Could this be related to pollution in the surgical room with inhalation anesthetics? Maybe, but there is still no proof, because there are several other situations that differentiate the surgical medical team from a non-surgical one, such as the stress of working in a surgical environment and the hours spent in these conditions.

Inhalation Anesthesia and Teratogenicity

Regarding teratogenicity, which refers to fetal malformation, there are very controversial studies that show both yes and no. Those correlating inhaled agents with teratogenicity often propose excessive exposure to inhalational agents in laboratory animals, for example, which is not consistent with clinical reality. However, because of this uncertainty, it is recommended that professionals in the first trimester of pregnancy do not remain in environments with high exposure to inhalation anesthetics. It's important to note that this does not apply to the patient who will undergo the procedure only once.

Inhalation Anesthesia and Mutagenicity

Mutagenicity follows the same line. There are still no studies proving that the concentration of inhaled anesthetic provided during anesthesia, or even environmental pollution in the room, can promote mutagenicity. However, a recent study found that people who spend many hours per week or for a long time in a surgical environment showed a higher percentage of micronuclei and cellular oxidative stress, which may be related to mutagenicity. Again, we need to study more about this.

What is the relationship between Inhalation Anesthesia and Cancer?

Inhalation anesthesia apparently is related to decreased immunity, which can favor metastatic conditions, for example. Now, correlating this with cancer goes far beyond what the information gives us. For example, a comprehensive study that assessed the risk of metastasis or worsening survival rates in women with breast cancer found no difference between the group subjected to inhalation anesthesia (2,246 patients) and the group subjected to intravenous anesthesia (3,085 patients) (Yoo et al. 2019).

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We also suggest that you read the position of the Brazilian College of Veterinary Anesthesiology (CBAV) regarding the relationship between cancer and anesthesia. There they describe, based on several scientific articles, that "the choice between intravenous or inhalation anesthesia cannot be guided by the risk of tumor recurrence."

In light of all this, what we really need to do is reduce the exposure of the surgical team to the inhalation agent, especially by implementing an appropriate anti-pollution system (passive or active), avoiding mask induction, refraining from frequently filling and/or emptying the anesthetic vaporizer, and preferring a valvular closed-circuit system when possible.

So, if you, as an anesthetist, want to use inhalation anesthesia in your patient, go ahead. If you want to use TIVA, go ahead, no problem. What matters is that you perform a proper procedure, minimizing risks for your patient, and that's it.

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Read also about:

• Inhalant Anesthesia - Anesthesia Unravelled #16
• Anesthetic Systems - Anesthesia Unravelled #15
• Universal Vaporizer - NAVE Answer

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Find out more:
– Colégio Brasileiro de Anestesiologia Veterinária – Posicionamento do Colégio Brasileiro de Anestesiologia Veterinária (CBAV) sobre a relação entre câncer e anestesia, 2021.
– Silva et al. Evaluation of genetic instability, oxidative stress, and metabolism-related gene polymorphisms in workers exposed to waste anesthetic gases. En. Science and Pollution Res, 30:9609-9623,2023.
– Yoo eet al. Total Intravenous Anesthesia versus Inhalation Anesthesia for Breast Cancer Surgery: A Retrospective Cohort Study. Anestesiology, 130, 31-40,2019.

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