Detection of Lymph Node Positivity in Patients With Invasive Ductal Breast Cancer Using Immun Checkpoint Washout

The most common cancer in women worldwide and the leading cause of death among those aged 20-59 is breast cancer. Invasive breast cancers are primarily classified as ductal and lobular. However, special types of invasive breast cancers, which constitute 10% of total cases, have been included in the current histological classification.

Invasive ductal carcinoma is the most frequently observed type among invasive breast cancers (80%) and is also defined as invasive ductal carcinoma of no special type. Macroscopic or microscopic axillary lymph node metastases have been detected in up to 25% of screening-diagnosed cases and up to 60% of symptomatic cases of invasive ductal carcinoma.

The clinical staging of breast cancer is primarily determined by the physical examination of the breast skin, breast tissue, and regional lymph nodes (axillary, supraclavicular, and internal mammary). However, the accuracy of clinically determining axillary lymph node metastases is only 33%. Proper lymph node staging in breast cancer patients is crucial for both prognosis and treatment.

Ultrasound is significantly more sensitive than physical examination alone in determining axillary lymph node involvement in breast cancer staging. For lymph nodes that remain indeterminate or suspicious on ultrasound, fine-needle aspiration biopsy or core biopsy provides a definitive diagnosis. The most commonly used staging system is the TNM staging system. The American Joint Committee on Cancer (AJCC) recently modified the TNM system. According to the latest TNM staging, the presence of macrometastases in ipsilateral level 1 and level 2 axillary lymph nodes classifies breast cancer as stage 2A or higher. Although biopsy sampling has a high diagnostic accuracy, it requires experienced pathologists, and the evaluation process can take weeks. Therefore, there is a need for faster and more cost-effective diagnostic methods for detecting axillary metastases.

The lymph node washout technique is used to determine lymph node metastasis in malignancies such as papillary thyroid carcinoma, the most common type of thyroid cancer. Papillary thyroid carcinomas generally do not exhibit aggressive clinical behavior and have favorable long-term prognoses. However, at the time of diagnosis, cervical and mediastinal lymph node involvement ranges from 27% to 46%, and the postoperative recurrence rate is between 3% and 30%. Thus, determining preoperative lymph node involvement and distinguishing it from benign reactive lymphadenitis is essential. For this purpose, fine-needle aspiration with thyroglobulin washout sampling has recently become widely used worldwide. In patients with papillary thyroid carcinoma, fine-needle aspiration of cervical lymph nodes and testing for thyroglobulin, a protein normally present in thyroid tissue, is considered one of the most reliable methods for detecting lymph node metastasis. A large-scale study by Moon et al. found that fine-needle aspiration thyroglobulin washout had a sensitivity of 93.2% and a specificity of 95.9% in detecting lymph node metastases in papillary thyroid carcinoma.