This research aims to investigate the effect of mindfulness-based stress reduction training given before mastectomy on postoperative early period pain and the fear of movement caused by pain. According to the World Health Organization, 18.1 million new cancer diagnoses are made each year, with breast cancer being the most common type among women, accounting for 24.2% of all cancers diagnosed. In Turkey, the incidence of breast cancer was determined as 22,345 in 2018. Breast cancer significantly affects women's quality and length of life. Surgical intervention is the most commonly chosen treatment method for cases of localized breast cancer. Pain and limited movement are among the most common problems encountered after surgery. Non-pharmacological methods have been shown to be effective in pain management, with the mindfulness-based stress reduction technique being one of these methods. This technique is described as an effective treatment for conditions such as pain, depression, and addiction, with high levels of mindfulness being associated with greater self-esteem, optimism, and empathy, whereas low levels of mindfulness are linked to depression, anxiety, chronic pain, and acute pain.

This research aims to explore the effectiveness of mindfulness-based stress reduction (MBSR) training, delivered through an eight-session program prior to mastectomy, in alleviating postoperative pain-a critical challenge in breast cancer treatment. Recognizing the substantial impact of breast cancer on women's quality of life and the limitations of traditional pharmacological approaches to pain management, this study proposes a non-pharmacological intervention. By employing an experimental design, it investigates whether preoperative MBSR training can lead to a significant reduction in pain levels among patients undergoing mastectomy, compared to those who do not receive such training. The hypothesis suggests that mindfulness training, by fostering higher levels of mindfulness, may improve pain management, thereby enhancing patient outcomes and suggesting a potential shift towards incorporating holistic preparatory training in standard preoperative protocols. This approach aims to contribute to the evolving landscape of pain management strategies in breast cancer care, emphasizing patient-centered and integrative treatment modalities.

Inclusion Criteria:

• Verbally and in writing agreed to participate in the study after being informed about the research, Are aged 18 and over, Can read, write, and speak Turkish, understand the provided information, and have no issues with verbal communication, Do not have any physical issues that would prevent participation in mindfulness-based stress reduction training, Have not previously received mindfulness-based stress reduction training, Underwent surgery with general anesthesia, Had arterial blood pressure, pulse, oxygen saturation, and body temperature within normal limits during and after surgery, Received non-narcotic and consistent analgesic substances postoperatively for pain control, Were administered antibiotics postoperatively with the same active ingredient.

Exclusion Criteria:

• Patients without internet access, Those unable to use the application through which the training is provided or without someone to assist them, Individuals who cannot allocate regular time for the training, Patients with chronic pain during the preoperative period who are using analgesics for treatment, Patients with restricted movement activity before the surgery will not be included

being female