Various regional anesthesia techniques, either individually or in combination, can be utilized for analgesia in breast cancer surgery. This study aims to map the cutaneous sensory block areas of different regional anesthesia techniques (serratus anterior plane block, parasternal block, and interpectoral + pectoserratus plane block) applied to patients undergoing breast cancer surgery. Furthermore, the extent to which these blocks cover the modified radical mastectomy incision will be assessed. The study seeks to comparatively determine the minimum and maximum sensory spread of each block. Ultimately, the findings are intended to provide valuable data for developing tailored perioperative pain management strategies specific to the surgical procedure and individual patient needs.

Breast cancer is the most common type of cancer in women, and surgical intervention is frequently employed as a treatment modality. However, the choice of surgical approach may vary depending on the tumor subtype and the extent of metastasis. The orientation of the surgical incision also differs based on the tumor location and/or the presence of axillary involvement.

Accurately identifying the anatomical location of the affected tissues during breast surgery is of critical importance for planning an effective perioperative analgesia strategy. Procedures such as lumpectomy, partial mastectomy, and therapeutic mammoplasty primarily involve the skin and subcutaneous breast tissue. Depending on whether the surgery is performed medial or lateral to the nipple, the anterior or lateral cutaneous branches of the intercostal nerves play a role in innervating the surgical area. In more extensive surgeries such as modified radical mastectomy (MRM), nerves originating from the brachial plexus (pectoralis, thoracodorsal, and long thoracic nerves) may contribute to perioperative pain. These procedures typically involve the dissection of all subcutaneous breast tissue, the overlying skin, and the pectoralis and serratus anterior muscles and often necessitate sentinel lymph node biopsy or axillary dissection.

Due to these factors, various incision types are used in oncological breast surgeries depending on the type of surgery. Therefore, a patient-specific perioperative pain protocol should be established for each procedure, and the most appropriate regional anesthesia technique should be selected accordingly.

In the literature, serratus plane blocks, paravertebral block, interpectoral, and pectoserratus blocks, as well as their combination, have been reported to provide effective perioperative pain management in breast cancer surgery. These techniques offer benefits such as reducing acute and chronic pain, minimizing the surgical stress response, facilitating early mobilization, decreasing opioid consumption, and ensuring a more hemodynamically stable perioperative period.

In the investigators' clinic, regional anesthesia techniques guided by ultrasound are routinely administered, either alone or in combination, to manage perioperative pain in patients undergoing breast cancer surgery. These techniques include serratus anterior plane block, parasternal block, and interpectoral + pectoserratus plane block.

The study was designed as an observational clinical trial to evaluate patients undergoing breast cancer surgery who received regional anesthesia for perioperative pain management. The primary objective is to evaluate the cutaneous sensory block areas of these blocks and compare the blocked sensory areas with the modified radical mastectomy incision to assess the minimum and maximum sensory spread of each block.

Inclusion Criteria:

• Patients with unilateral breast cancer surgery
• Patients receiving regional anesthesia as part of their perioperative analgesia management
• Aged between 18 and 70 years.
• ASA<IV
• Patients who agree to participate and provide written informed consent

Exclusion Criteria:

• Patients who refuse to participate.
• Patients who have not undergone any regional anesthesia technique.
• ASA>III
• Bilateral mastectomy.
• History of previous breast surgery (except excisional biopsy).
• Cognitive impairment or dementia.
• Patients with psychiatric disorders such as depression, mania, or schizophrenia.

Female patients scheduled for breast cancer surgery will be included.

Patients scheduled for breast cancer surgery and receiving regional anesthesia as part of their perioperative analgesia management will be included in the study.