This study compares two methods of local pain control in patients undergoing Modified Radical Mastectomy, a common surgery for breast cancer( tumor in the breast) treatment. It aims to determine which method, the Thoracic Interfascial Plane Block or the Erector Spinae Plane Block, provides better pain relief after surgery, reduces side effects, and increases patient satisfaction. Why This Study Is Important: Breast cancer surgery can cause significant pain, and managing this pain is important for a quick recovery. Currently, pain is often managed with opioids, which can cause side effects like nausea and drowsiness. invistigators want to find a method that controls pain effectively with fewer side effects, helping patients recover faster and feel better. Who Can Take Part: Women aged 21 and older who are scheduled for a Modified Radical Mastectomy at Ain Shams University hospitals can participate in this study. What Will Happen During the Study: Participants will be randomly assigned to receive either the Thoracic Interfascial Plane Block or the Erector Spinae Plane Block before surgery. Pain levels will be measured using a numerical pain score from 1 to 10. Researchers will track the amount of pain medication needed, the time it takes to feel pain relief, and any side effects. Other factors such as sleep quality, time to start walking again, and overall satisfaction with pain control will also be recorded. What investigators hope to Learn: Investigators hope to find out which nerve block provides better pain relief after surgery. By comparing TIPB and ESPB, with the aim to identify the method that: Requires less additional pain medication Has fewer side effects Improves sleep quality and overall recovery Increases patient satisfaction Significance: This study could lead to better pain management strategies for breast cancer surgery, reducing the need for opioids and enhancing patient recovery and comfort. Participation: Participants will be monitored closely during and after the procedure to ensure their safety and well-being. The results of this study could help improve pain management for future patients undergoing similar surgeries.