| BackgroundThe sentinel lymph node is the first regional lymph node to accept primary tumor draining, and also the first stop where tumor metastasis would occur. Hence, it could be used to predict the regional lymph node metastasis status of gastrointestinal cancer. Sentinel lymph node navigation surgery (SNNS) was originally applied in accessing the extent of lymph node dissection in patients with breast cancer and melanoma, and it has recently been applied in the gastrointestinal surgeries as well. Saha, in 1997, first reported SNNS in treating one colorectal cancer patient. Also in 2000, Miwa K first reported applying SNNS during surgery of a gastric cancer patient. Till recently, many studies have confirmed the prediction of sentinel lymph node in gastrointestinal cancers. The accuracy rate varied from 58% to 100%. All these early experiences of SNNS showed that this technique might provide a different insight in surgery as well as adjuvant treatment for gastrointestinal cancer. To mention that, with the development of gastrointestinal fiberoscopy, the incidence of early gastrointestinal caner increases in China year by year. Biopsy of sentinel lymph node could enable surgeons to better conduct the pre-and intra-operative cancer staging and subsequently choose the appropriate, individualized surgical approach so as to give accurate treatment for early cancer patients, like endoscopic mecosal resection, laparoscopic segment resection, etc. rather than conducting traditional radical gastrectomy or mesorectal excision to reduce postoperative mobidity and improve postoperative quality of life together with similar oncological efficacy. As is known to all that regional lymph node metastasis is key to predict outcomes of patients with gastrointestinal cancer. However, the most common current pathological examination used in China is still the traditional hematoxylin eosin (HE) staining, and this method for detecting lymph node metastasis sometimes yields very high false negative rate, especially in early gastrointestinal cancer patients with regional lymph node micro-metastases. Also to mention that due to the high expense and long time duration, applying IHC or PCR for all the regional lymph nodes is of low clinical feasibility. Whereas it is still advocated to conduct IHC or PCR in limited sentinel lymph nodes to precisely predict regional lymph nodes metastasis.The SNNS in gastrointestinal cancer patients may be useful in providing patients with individualized treatment, but its application remains controversial and is not widely applied. The main reason is that due to the complicated and multi-direction lymphatic drainage network along stomach and intestine and the high incidence of lymph node jumping metastasis, it is rather difficult to accurately locate sentinel lymph node.To deal with the problem, many methods have been tried for locating sentinel lymph node. Among them, the most commonly used one is the plain visual observation:Inject dye into mucosa or subserosa around the primary tumor during operation and observe. The fist stained lymph node is defined as sentinel lymph node. The method is convenient and nor requiring. But the disadvantage is that most dye is rapidly metabolized in lymphatic vessels and lymph nodes, in addition,1-4% of the sentinel lymph nodes are not within the routine extent of lymph node dissection, especially in some obe-patients, a lot of observation blind spots restrain surgeons from observing the entire area and accurate defining sentinel lymph node. Thus, the plain visual observation is not stable in search for sentinel lymph node. To compensate for the visual disadvantage, many researchers improve the method by combining dye and radionuclide:Inject radionuclide into submucosa around the tumor one day before operation and make another infection of dye during operation. Look for the first stained lymph node as mentioned above and also scan all the regional lymph nodes withγdetector. Select the node which has a radiation over 10 times than the background surroundings and define it as the sentinel lymph node. In this way, the detection of sentinel lymph node could be more accurate and stable. But on the other hand, to applyγdetector during operation might significantly increase the operative time. Recently, SPECT/CT was also applied by some fellows to show the 3D anatomic structure of sentinel lymph node, and this brand-new method was successfully attempted in breast cancer, prostate cancer, melanoma, gynecologic cancer and head and neck cancer.In the present study,99mTc-SPECT/CT combined with nano-carbon suspension injection were applied to evaluate its feasibility and clinical value for detection of sentinel lymph node in gastrointestinal cancer.ObjectiveThe purpose of this study was to evaluate the accuracy of SLM in patients with rectal and gastric cancer by single-photon emission computed tomography/computed tomography (SPECT/CT) lymphoscintigraphy and carbon nanoparticles suspension injection. MethodsTwelve patients with clinical T1-2N0M0 rectal cancer and six patients with clinical T1-2N0M0 gastric cancer were selected and locally injected with technetium-99 m sulfur-colloid and carbon nanoparticles suspension injection by endoscope one day before operation, followed by SPECT/CT scanning 1,3 and 5 hours later. Radioactive isotope (RI) uptake of each node from sentinel nodes(SNs) basin with location preoperatively determined by SPECT/CT was postoperatively calculated using gamma probe.The node or nodes with the highest RI uptake, the number of which was also determined by SPECT/CT, was defined as SNs. Immunohistochemical cytokeratin staining was performed for all the SNs and non-SNs.Results1. For the patients of rectal cancer, the rate of sentinel node detection was 91.7%(11/12) with at least one SN(1-3) per patient. Ten cases showed metastasis-negative in SNs and all the resected regional nodes by Immunohistochemical cytokeratin staining. Only one case was double positive in both SN and non-SNs. The accuracy of SLM was 100%.2. For the patients of gastric cancer, the rate of sentinel node detection was 100%(6/6) with at least one SN(1-2) per patient. All the cases showed metastasis-negative in SNs and all the resected regional nodes by Immunohistochemical cytokeratin staining. The accuracy of SLM was 100%.ConclusionSPECT/CT lymphoscintigraphy and carbon nanoparticles suspension injection can effectively detect anatomic location and number of sentinel nodes and improve the accuracy of SLM in patients with rectal cancer and gastric cancer. |
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