The Systematic Research Of^99mTc-sulfur Colloid In Sentinel Lymph Node Of Breast Cancer

Background：1. Breast cancer is one of the world’s most common malignancies of women, andthe incidence rate was gradually rising trend. The sentinel lymph node (SLN) is thefirst draining node on the direct drainage pathway from the primary tumor site.Lymph node metastases of breast cancer have certain regularity, and appear less likelyto skip metastasis. This feature provides anatomical basis on performing SLN biopsyin breast cancer and breast conserving therapy. It can predict the region lymph nodestatus of breast cancer, If no SLN metastasis, the theory that there is no lymph nodemetastasis next station. The sentinel lymph node biopsy (SLNB) on breast cancer issimple, less invasive, safe, effective staging, etc. And it can effectively avoidsensation abnormalities, numbness, arm pain, lymphedema, and shoulder mobility andother complications which caused by axillary lymph node dissection (ALND). SoSLNB has been widely used in breast cancer, and has become a routine means ofdiagnosis of breast cancer patients at present. For the drainage pathways in breastcancer patients, axillary lymph drainage is the most common drainage, but in additionto the axillary lymph drainage, internal mammary lymph drainage is also important.Lymphatic scintigraphy demonstrated that there are up to45%of breast cancerpatients’ lymph draining into the internal mammary lymph node chain.[1]Internalmammary lymph node status also plays a crucial role on assessing the prognosis ofpatients with breast cancer. A number of studies show that there are very important impact on assessing the status of the internal mammary lymph node in breast cancerpatients, because it is important for the treatment, the recurrence rate and the survivalrate.[2-5]Various existing methods recommended have highly detection rate for axillary SLN,but the internal mammary SLN detection rate is low. Subcutaneous or intradermalinjection has been widely used in radionuclides preoperative lymphoscintigraphy, butalmost can not recognize the extra-axillary SLN. The intraparenchymal injection wasmore reliable, but the internal mammary SLNs in lymphoscintigraphy were seen onlyin a small proportion of patients (range from11to37%).[5-7]2.99mTc-sulfur colloid (SC)，as the first radioactive technetium labeled colloidfor lymphoscintigraphy，is also the most widely used. Its particle diameter range from5nm to5000nm, and the average diameter range from100nm to600nm. But it willhave the different particle size distribution in different preparation methods. Thecolloidal particle size distributions affect its biological behavior, and thus have animpact on the imaging results. The colloid particle size less than4-5nm will come intothe capillaries and into the blood circulation system[8]. And the colloidal particlediameter will flow rapidly from the injection site and significant retention in thelymph node for up to5h when particle size less than100nm, but when the colloidparticle diameter larger than500nm, it will stay at the injection site mostly.[9]ObjectiveTo investigate the optimal method of SLNB by studying the effects of99mTc-SCon the different preparations and injecting methods on sentinel lymph node (SLN)detection in breast cancer.Methods：1.99mTc-SCs were prepared by controlling the heating time at1,3,5,8,10and12min. And the RCP, morphology and colloid particle size distribution were determinedby thin layer chromatography (TLC), transmission electron microscopy and laser lightscattering techniques respectively at the time of pre-filteration, after post-filteration placed10min,1h,2h, and4h, and to explore its regularity.2.99mTc-SCs were prepared by controlling the heating time at3min (radiotracer1)and5min (radiotracer2) respectively. The147breast cancer patients were involvedand randomly divided into three groups:(A)40patients were injected periareolarlywith the radiotracer1;(B)40patients were injected periareolarly with the radiotracer2;(C)67patients were injected peritumorally with the radiotracer2. All patients wereperformed lymphatic mapping using SPECT/CT preoperatively and receivedsubdermal injection of blue dye on the tumor. The axillary and internal mammarySLN detection rates were recorded.Resluts：1. TLC Results: The RCPs of pre-filtration and post-filtration99mTc-SC underdifferent heating time were no significant difference (t=1.905, P=0.099). When theheating time was1,3,5,8,10min, the RCPs of filtered99mTc-SC were stable within4h, and the average was (81.17±1.26)%,(96.12±1.15)%,(95.8±1.13)%,(94.98±1.29)%,(97.37±0.85)%. When the heating time was12min, the RCP of filtered99mTc-SC was (92.28±1.22)%in3h, then reduced to (86.05±0.68)%at4h.2. Laser light scattering measurements: The particle size stability studiesdemonstrated that there were no significant changes in particle size distribution over4h (P＞0.05). Prolonged the heating time from3min to5min, the particles of thefiltered99mTc-SC within100nm was significantly reduced (73.72±2.36VS65.25±3.56, t=6.436, p=0.000), the particles of greater than500nm increased significantly(12.76±3.65VS19.19±3.31, t=4.291, P=0.000). Prolonged the heating time from5min to12min, the particles less than100nm were not decreased, and the particleslarger than500nm were not increased significantly (P＞0.05). When the heating timewas prolonged from3min to5min, the average effective particle size of filtered99mTc-SC increased significantly (45.27±6.72VS75.59±7.04, t=7.315, P=0.000).Prolonged the heating time from5min to10min, the average effective diameter wasno significant difference (p=0.530). But the heating time was extended to12min, the average effective particle size increased significantly (p=0.010).3． Transmission electron microscopy Results: Microscope showed that the99mTc-SC was spherical and spherical. It had varying sizes and some werepolymerized state. Some distortion of the particle shape may caused by the dryingprocess on the grid or the heat from the electron beam. Pollution particles can beobserved, and the lower peak in the particles size distribution may be thecontaminated. When the heating time was5,8,10,12min, the number of the largeparticles was higher than the heating time was1,3min in microscope.4. Imaging: The success rate of three groups internal mammary SLN imagingrespectively was70%(28/40),47.5%(19/40) and17.9%(12/67), and the differencewas significant statistically (x2=29.525, p=0.000). The success rate of three groupsaxillary SLN imaging respectively was100%(40/40),95%(38/40) and97%(65/67),the difference was not statistically significant (x2=2.686, p=0.261).5. Intraoperative lymph node detection: preoperative lymphoscintigraphy withradionuclide and blue dye method intraoperative detection combined. Group A: theSLNB success rate was100%(40/40). About3-7lymph nodes per case was detected,and the average number is (4.00±1.25) per case. The axillary SLN detection rate was100%, and the axillary SLN success rate of marks blue dye was90%(36/40). GroupB: the SLNB success rate was97.5%(39/40). About0-6lymph nodes per case wasdetected, and the average number is (3.05±1.14) per case. The axillary SLNdetection rate was97.5%(39/40), and the axillary SLN success rate of marks blue dyewas85%(34/40). Group C: the SLNB success rate was98.5%(66/67). About0-5lymph nodes per case was detected, and the average number is (3.03±1.34) per case.The axillary SLN detection rate was98.5%(66/67), and the axillary SLN success rateof marks blue dye was94%(63/67). The average number of lymph node detection ingroup A increased significantly than in group B and group C. The axillary SLNdetection rate was no significant difference (x2=0.947, p=0.623). The internalmammary SLN detection rate in there groups respectively was70%(28/40),47.5% (19/40) and17.9%(12/67), and the difference was significant statistically (x2=29.525, p=0.000).Conclusions：1．Filtration process does not change the RCP of99mTc-SC. When the heating timewas3min,5min,8min and10min, the pre-filter and post-filter99mTc-SC could meetthe RCP quality control requirements in4h. But when the heating time was1min and12min, the RCP of99mTc-SC could not meet the quality control requirements in4h.2. Transmission electron microscopy combined with laser light scatteringinstrument could effectively observe the morphology and size distribution of colloids.99mTc-SC has polymerization and depolymerization states. When the heating time was1min and3min, the percentage of particles less than100nm was maximum and theminimum percentage greater than500nm, the average effective particle size to aminimum. When the heating time was5,8,10and12minutes, the percentage ofparticles less than100nm and greater than500nm is no significant difference.Filtration process could make the average effective particle size decreases.3. For SLNB of patients in breast cancer, the excellent detection rates of theaxillally and internal mammary SLN could be achieved by SPECT/CT lymphaticmapping with radiotracer of which size reduced by shortening the heating timeinjected periareolarly in breast intraparenchyma guided by ultrasound, and combinedwith blue dye subdermal injection on the tumor subsequently.