For some solid tumors, surgical resection is the best approach available. Surgery causes the release of pro-inflammatory mediators and stimulation of the neuroendocrine system in the perioperative period. Additionally, surgery causes increased sympathetic stimulation and initiates a proinflammatory response to tissue damage. This pro-inflammatory response influences the cell-mediated immune response. Natural killer (NK) cells and CD8+ T cells both have antitumor activities and are associated with cortisol and catecholamine release. It also causes activation of pro-oncogenic cells, regulatory T cells, and type 2 helper T cells. This biological response to surgical stress may result in tumor cell survival and metastasis. Metastatic diseases are the most common cause of death in cancer patients. Exposure to anesthesia during surgery may also play a role in primary relapse or metastatic transformation. Agents used in the induction and maintenance of general anesthesia have interactions with the immune and neuroendocrine systems and may affect the stress response during surgery. Therefore, it is important to choose the best type of anesthesia that will help alleviate sympathetic and/or pro-inflammatory responses while modulating cytokine release and transcription factors/oncogenes. The effect of anesthesia may affect cancer cell survival and ability to metastasize, which can be stimulated not only during surgery but also during the immediate post-operative recovery phase. Studies on the effects of anesthesia methods and anesthetic drugs on tumor recurrence and metastasis are ongoing. It has been shown that volatile anesthetics such as sevoflurane and isoflurane may cause suppression of the immune system by blocking antigen-1-dependent integrin lymphocyte function. Non-volatile anesthetics such as ketamine have been shown to suppress Natural Killer (NK) cell cytotoxicity and inhibit the production of pro-inflammatory cytokines (IL-6 and TNF-α). It has been reported that opioids used alone in pain and pain treatment cause suppression of the immune system through NK activity. Regional anesthesia; It has been hypothesized that it may reduce cancer progression through different mechanisms, including modulation of the sympathetic response, avoidance of the harmful effects of general anesthetics and opioids, and direct immunomodulatory effects of local anesthetics. Peripheral nerve blocks are a regional anesthesia method used to reduce postoperative pain and opioid consumption in many primary tumor resections. In addition to the analgesic properties of local anesthetics and regional anesthesia methods used in regional anesthesia, their anti-inflammatory and antitumor effects have also been proven. The use of ultrasound (US) in peripheral nerve blocks for the last 10 years has increased the success rate in blocks and led to the discovery of new blocks. Fascial plane blocks (FPBs) are regional anesthesia techniques performed by needle insertion and injection into the space between two separate fascial layers. Analgesia is achieved by spreading local anesthetic to the nerves and adjacent tissues moving within this plane. In 2011, Rafael Blanco introduced a new method to analgesia methods after breast surgery by blocking the medial and lateral pectoral nerves of the brachial plexus between the pectoralis major and minor muscles (Pectoral Block I). Pectoral Block II was developed to be effective in axillary interventions. Ultrasound-guided Pectoral Block I and II (PECS I and II) are alternative methods to thoracic epidural and paravertebral blocks in preventing pain after breast surgery. In study, the investigators aimed to compare the effects of general anesthesia and peripheral nerve block (PECS Block) methods on the leukocyte, platelet-lymphocyte count and ratios, the total amount of opioids used, and discharge times in patients who underwent wire localized lumpectomy. It is aimed to ensure that the operation can be performed with peripheral nerve blocks, to protect the patient from immunosuppression that may be caused by general anesthetics and opioids, and to enable early discharge. The originality of the study is to investigate the usability of the PECS Block method not only as a postoperative pain method but also as an anesthesia method during surgery.

In addition, no clinical study has been found in the literature comparing the regional anesthesia method, which is applied only with local anesthetics, with the general anesthesia method.

The study was planned retrospectively. 26 patients who underwent wire localized lumpectomy for breast cancer treatment and diagnosis under general anesthesia (n=13) or PECS block (n=13) were found in hospital records. PECS block was applied to patients who had a high risk of general anesthesia or who did not want to receive general anesthesia during the pandemic. Patients who could not reach a sufficient block level and required additional doses of analgesics were not included in the study. In the PECS I block, local anesthetic was applied between the fascia of the pectoralis major and minor muscles, and in the PECS II block, local anesthetic was applied between the fascia of the pectoralis minor and serratus muscles. The surgery duration, total analgesic amounts pre- and post-operative leukocyte, neutrophil, lymphocyte, platelet levels, and discharge times were evaluated from the records.