Variants of Sentinel Lymph Node Research Protocols in Breast Cancer

Purpose: To study the advantages of the technique of administering a radiopharmaceutical according to the “two-day protocol” for determining the sentinel lymph node in breast cancer. Compare the methods of introducing radiopharmaccutical according to the “two-day protocol” and the “one-day protocol”. To identify the advantages of using the “two-day protocol” method over the “one-day protocol” method. Material and methods: In order to improve the diagnosis and treatment of breast cancer by means of a sentinel lymph node biopsy (SLNB) using the technique of introducing a radiopharmaceutical a day before surgical treatment, we analyzed 76 patients with various molecular biological types and stage of breast cancer disease who underwent examination and treatment in the conditions of the P.A. Herzen Moscow State Medical Institute. This cohort of patients was divided into 2 comparable groups: 1 group of patients who underwent SLNB according to a two-day protocol (n=38), the 2nd group of patients who underwent SLNB according to a one-day protocol (n=38). The ambient equivalent dose rate of photon radiation was measured using the MKS-08P dosimeter on the day of RP administration and on the day of surgery. Results: On average, the dose rate of photon radiation 0.5 m from the injection point on the day of radiopharmaccutical administration (according to the “one-day protocol”) and on the day of surgery (according to the “two-day protocol”) was 46.9±23.1(11.0‒85.4) and 2.2±1.1(1.0‒6.4) μSv/h, respectively. The average value of thedose rate directly in the colloid injection zone two hours after administration is equal to 185.1±25.7 (138.9‒258.0) μSv/h, a day later ‒ 9.8±3.8 (6.5‒27) μSv/h. In the first group, when using the “two-day protocol”, when scanning the SPECT/CT in 34/38 (89.5 %) patients revealed 83 lymph nodes, in the second in 30/38 (78.9 %) patients – 72; the total number of removed lymph nodes ‒ 147 and 156, respectively. With an urgent cytological examination, adenogenic metastases were detected in 8 cases in the first group, in 11 cases in the second. In 11/38 (29.0 %) patients, according to the “two-day protocol”, the number of detected and removed lymph nodes is equal, “according to the one-day protocol” ‒ in 5/38 (13.2 %). The scan did not reveal any SLN in the first group – 5/38 (13.2 %), in the second – 7/38 (18.4 %). Conclusions: The advantage of using the “two-day protocol” was revealed, consisting in an 18-fold decrease in background radiation. And also, a faster and more accurate determination of the sentinel lymph node in the surgical field using a gamma detector, associated with a minimum number of cases of scattered radiation in the area of regional lymph outflow, in contrast to the weak accumulation of “sentinel” lymph nodes and strong background radiation outside the nodes when a radioisotope is injected on the day of surgery. The “two-day protocol” greatly facilitates the work of the oncologist surgeon, contributes to a more accurate determination and biopsy of the sentinel lymph node, reduces the radiation load on medical staff during surgery.