The Preliminary Analysis of Sentinel Lymph Node Biopsy Guided by ^99mTc-Rituximab in Patients with Breast Cancer.

Objectives: Sentinel lymph node biopsy (SLNB) is a biopsy technique for assessing status of axillary lymph nodes. It is helpful for clinical staging and guide the choice of the surgical procedures. ^99mTc-Rituximab is a chimeric monoclonal antibody scintigraphy agent for CD₂₀ molecules on the surface of B lymphocytes in lymph nodes. The sentinel lymph node (SLN) is visualized by antigen-antibody reaction. In this study, sentinel lymph node biopsy guided by ^99mTc-Rituximab was performed in patients with breast cancer and analyzed for clinical application.

Methods: Study subjects were 54 women who were diagnosed with breast cancer and were eligible according to the exclusion criteria. All patients have pathological results. The median age was 55.43±11.00 years (range, 34-74). Exclusion criteria: Patients who suffered from inflammatory breast cancer, axillary lymph node biopsy metastasis but did not receive neoadjuvant therapy, axillary lymph node biopsy metastasis and received neoadjuvant treatment but still positive. Pregnant patients were also excluded. ^99mTc-Rituximab was injected in the intradermal and adjacent glands on the surface of the tumor with the dose of 18.5MBq/0.8ml. Except for 6 patients, all the patients were performed anteroposterior and posterior planar static scintigraphy and SPECT/CT scintigraphy within 1-3 h after injection, followed by surgical treatments. Intraoperative SLN was determined by two means: 1. The methylene blue was injected next to the tumor or surgical incision and SLN was identified as the site where the blue-stained lymph nodes or blue-stained lymphatic vessels disappeared; 2. Intraoperative gamma probe detection count exceeded 10% of the injection point or other than the highest point of the injection point was determined as SLN. And then, gamma probe again reviewed to make sure the resection of lymph nodes be SLN. If hot spots weren’t detected on the SPECT/CT tomographic scintigraphy, though the intumescent lymph nodes were suspected to be metastatic lymph nodes, they were still hard to be confirmed as SLN or not, so this situation was also defined as negative.

Results: 1. The success rate of the SLNB method guided by ^99mTc-Rituximab was significantly higher than that of guided by methylene blue method (96.30% VS 68.52%). The difference was statistically significant (P<0.005). 2. The median number of SLN in the static image, SPECT/CT tomography, and the “hot spots” in the gamma detector during the operation were 1.46±0.944(range,0-4), 1.73±1.333(range,0-7), and 1.48±0.714(range,0-3), respectively. There was no statistical significance (P=0.162). The median number of SLN remove in the surgery actually was 3.69±2.536(range,0-11). There was significant difference between number of “hot spots” under the guide of gamma detector and SLN remove in the surgery actually (t=-6.830; P<0.005). 3. The false-negative rate of sentinel lymph node biopsy was 7.41% (4/54). In 2 case, SLN was not found by the gamma probe and were confirmed to have metastases in the axillary lymph nodes after operation. In other 2 cases, SLN scintigraphy was positive, SLN without metastases, but axillary lymph nodes metastases were pathologically confirmed finally. 4. Among the SLN metastatic patients, there were 18 cases with positive SLN scintigraphy and 4 cases with SLN scintigraphy negative. However, all 26 cases without metastasis were positive with SLN scintigraphy. There was significant difference in the positive rates of SLN scintigraphy between SLN metastasis and without SLN metastasis (X²=5.157; P=0.038). The positive rates of SLN scintigraphy was higher in the patiernt without SLN metastasis.

Conclusions: Sentinel lymph node biopsy with ^99mTc-Rituximab has high success rate and low false-negative rate. It is beneficial to the choice of individual treatment schedule. It can reduce unnecessary lymph node dissection and avoid sugery complication and has a high application value.