This study evaluates the efficacy and feasibility of Carbon Nanoparticle Suspension Injection (CNSI) for Targeted Axillary Dissection (TAD) in breast cancer patients undergoing neoadjuvant chemotherapy (NAC), compared to traditional clip-based methods. By leveraging CNSI's enhanced visibility and stability, the study aims to improve the precision of lymph node removal, reduce surgical complications, and potentially transform clinical practices. Conducted across multiple centers, this randomized controlled trial focuses on clinical outcomes such as lymph node retrieval rates and the accuracy of surgical staging, aiming to establish a safer, more effective approach to managing axillary lymph nodes in breast cancer surgery.

Objective: This study aims to assess the clinical feasibility, accuracy, and effectiveness of CNSI in targeted axillary dissection compared to traditional tissue marker clips in patients with breast cancer undergoing neoadjuvant chemotherapy (NAC).

Background: Breast cancer remains one of the most prevalent cancers among women globally. Neoadjuvant chemotherapy (NAC) has significantly advanced the management of locally advanced breast cancer, enabling more conservative surgical approaches and reducing the dependency on axillary lymph node dissection (ALND), which is often associated with long-term complications such as lymphedema and chronic pain. Traditional TAD methods using tissue marker clips have challenges including high costs and potential for marker loss. CNSI presents a novel approach with potential for enhanced surgical precision and reduced complication rates.

Methods: The study employs a multicenter, randomized controlled trial design to compare the outcomes of TAD using CNSI versus conventional clip-based methods. Patients with clinically node-positive breast cancer who achieve clinical node-negative status post-NAC are enrolled. The primary endpoints include the rate of successful lymph node retrieval, the incidence of surgical complications, and the accuracy of lymph node staging.

Innovation: CNSI is designed to improve the visibility and stability of lymph nodes during surgery, potentially increasing the precision of cancerous node removal and minimizing the need for subsequent surgical interventions. Its unique properties, such as the slow metabolic rate and strong pigmentation, ensure prolonged visibility and facilitate easier identification during surgery.

Significance: By enhancing the effectiveness of TAD, CNSI could transform clinical practices in breast cancer surgery, reducing the physical burden of surgery and improving the quality of life for patients. The study's findings could lead to broader adoption of CNSI in surgical oncology, setting a new standard for axillary management in breast cancer.

Conclusion: This research could significantly impact breast cancer treatment protocols by providing a safer, more cost-effective, and clinically advantageous method for axillary lymph node management, potentially leading to widespread changes in surgical approaches and patient outcomes.

Inclusion Criteria:

1. Female patients aged 18 to 85 years are eligible.
2. Participants must have a histologically confirmed diagnosis of breast cancer, classified as cT1-4N1-2aM0 according to the 8th edition of the AJCC (American Joint Committee on Cancer) TNM classification system.
3. Eastern Cooperative Oncology Group (ECOG) performance status must be 0 or 1.
4. Clinical re-staging must indicate an axillary node status of ycN0 following NAC.
5. Participants must provide written informed consent to partake in the trial, acknowledging understanding and agreement to the procedures and risks involved.

Exclusion Criteria:

1. Patients with metastatic breast cancer (Stage IV).
2. Diagnosed with inflammatory breast cancer or bilateral breast cancer.
3. History of axillary surgical procedures.
4. Any medical, psychological, or social conditions that would prevent adherence to the study protocol or completion of the treatment or follow-up.
5. Known allergy to carbon nanoparticles or presence of severe comorbid conditions or other serious underlying medical issues.
6. Current or prior participation in another clinical trial that could interfere with the outcome of this study or affect the safety and well-being of the participants.