Sentinel lymph node biopsy (SLNB) is the standard of axillary lymph node surgical staging in patients with early breast cancer.

The main goal of the study is to abandon axillary surgery in patients over 59 years old with early, luminal A, clinical lymph node negative breast cancer.

Sentinel lymph node biopsy (SLNB) has replaced axillary lymph node dissection (ALND) in early breast cancer and has been widely implemented in clinical practice worldwide. The primary goal of SLNB is to reduce the complications associated with ALND while maintaining high anti-tumor efficacy.

However, many studies have shown that although SLNB reduces the complications typical of ALND, the incidence of these complications remains high: the risk of developing lymphedema is 7.5%, sensory disturbances and restrictions in arm movement occur in 5-8% of cases. It is well known that these complications negatively affect the physical, psychological, and emotional well-being of women, thereby reducing their quality of life.

It is also noteworthy that there is a relatively high rate of false-negative results in SLNB (ranging from 4.6% to 16.7%).

Due to advances in imaging diagnostic methods, the accuracy of preoperative assessment of lymph node status has significantly improved. According to studies, the sensitivity and specificity of ultrasound examination of the axillary lymph nodes in diagnosing lymph node involvement are 85% and 78%, respectively. Other sources, however, report a 15.5% of false-negative rate in preoperative ultrasound examinations. Consequently, the diagnostic field of standard radiological methods (ultrasound, CT, MRI) in assessing axillary lymph node status is deemed 'insufficient'. Mammolymphoscintigraphy is an additional diagnostic method based on the detection of pathophysiological alterations in the energy metabolism of tumor cells at the subcellular and molecular levels. Moreover, since metabolic changes usually precede anatomical reorganization, functional imaging methods are regarded as having greater sensitivity in identifying neoplastic changes. Our own experience with radiolabeled 99mTc lipophilic cations in diagnosing axillary lymph node metastasis breast cancer demonstrated that the sensitivity, specificity, and overall accuracy of the method were 80%, 84%, and 76%, respectively. Therefore, in this study, we are incorporating mammolymphoscintigraphy as an essential method for determining lymph node status.

In recent years, the status of axillary lymph nodes has played a diminishing role for adjuvant therapy in early breast cancer patients. Furthermore, in the luminal A subtype of early breast cancer, hormone therapy will be prescribed in the adjuvant setting regardless of axillary lymph node status.

Thus, the existing clinical data do not allow for a definitive conclusion regarding the role of SLNB in early breast cancer patients with the luminal A subtype. To address this and other questions, the present study was initiated

Inclusion Criteria:

1. HER2-negative breast cancer (ER +/ PR +), Ki67 <= 30%, G1-2
2. age> 59 years.
3. morphologically confirmed diagnosis of breast cancer, IA-IIA stage
4. ECOG score 0-2.
5. the absence of contraindications to surgical intervention (including anesthetic risk is taken into account).
6. patient is able to provide informed consent and sign approved consent forms to participate in the study.
7. patients after surgical treatment in the scope of breast resection with sentinel lymph node biopsy (SLNB, group 1) or without axillary surgery (without SLNB, group 2).
8. N0 status of axillary lymph nodes according to ultrasound and SPECT-CT of the breast with 99mTc-Technetril.

Exclusion Criteria:

1. Inconsistency with inclusion criteria.
2. stage T2-4, N1 or M1 cancer
3. severe uncontrolled concomitant chronic diseases or acute diseases
4. previous/concurrent malignancy or history of radiation therapy to the chest wall region
5. any condition that is a contraindication to radiation therapy

5. pregnancy