Sentinel Node Navigation Surgery Research Articles

Assessment of lymph node micrometastasis in early gastric cancer in relation to sentinel nodes

The development of endoscopic resection and reduced surgical procedures has progressed in recent years. Lymph node micrometastases can be cited as one of the problems with reduced operations. In this study, we investigated clinicopathological findings and sentinel lymph nodes (SNs) for associations with micrometastases. We discuss the indications for endoscopic mucosal resection (EMR), reduced surgery, and sentinel node navigation surgery (SNNS) based on the results. Immunostaining with anti-cytokeratin antibodies was used as the method of exploring for micrometastases. Comparisons and assessments were made in regard to the presence or absence of micrometastases and various clinicopathological factors. The relationship between the clinicopathological factors and micrometastases was investigated in 120 patients with pT1pN0 gastric cancer. Significant differences in depth of invasion (mucosal [m] versus submucosal [sm]) and histological type (differentiated versus undifferentiated) were observed in both univariate analysis and multivariate analysis. Micrometastases were observed in 32% of the sm cancers, and they were observed in group 2 lymph nodes (no. 7) in 8%. They tended to be more common in the undifferentiated type. The micrometastatic lymph nodes were restricted to blue nodes (BNs) and lymph nodes within the dye flow area of patent blue (used intraoperatively explore for SNs). It is considered that the indications for current EMR and reduced surgery in early gastric cancer are valid from the standpoint of micrometastases. But if the SNNS that has been studied in recent years is introduced, the lymphatic basin dissection method seems valid only if the case is s-pN0 early cancer.

Area of Nodal Metastasis and Radioisotope Uptake in Sentinel Nodes of Upper Gastrointestinal Cancer

Sentinel node navigation surgery has been introduced for the treatment of gastrointestinal tumor. As few studies have examined relationships between metastatic area and radioisotope uptake in sentinel nodes, the present study examined this relationship for gastric and esophageal cancers. Subjects comprised 43 patients (esophageal cancer, n = 19; gastric cancer, n = 24) with < or =3 lymph node metastases in whom sentinel node mapping with radio-guided methods was performed. Radioisotope uptake was measured after surgery for all dissected lymph nodes. Metastatic area was calculated using the following formula: metastatic area (%) = (area of metastasis/total area of lymph node) x 100. Based on radioisotope uptake, lymph nodes were divided into RI(-) and RI(+) groups. In 35 patients, > or =1 metastatic node was present among the sentinel nodes. In 1 patient, no sentinel nodes were detected. No lymph node metastasis was found in sentinel nodes in the remaining seven patients. Lymph nodes were diagnosed as metastatic using preoperative imaging. Mean (+/-SD) metastatic area was significantly higher for RI(-) (68.3 +/- 20.5%) than for RI(+) (15.1 +/- 20.8%; P < 0.0001). Radioisotope uptake was decreased in lymph nodes with >60% metastatic area. The fact that radioisotope uptake is not detectable in some lymph nodes with >60% metastatic area must be considered when planning sentinel node navigation surgery.

Individualization of lymphadenectomy in superficial esophageal squamous cell cancer

As the result of the development of imaging means, the incidence of discovery of superficial esophageal squamous cell cancer (ESCC) has recently increased. Various treatment methods such as endoscopic mucosal resection and reduction of lymphadenectomy have been performed to preserve the quality of life. Because lymph node metastasis occurs even in the early stage of esophageal cancer, we should carefully select the treatment method, including lymphadenectomy. We analyzed the distribution of solitary lymph metastasis of 27 superficial esophageal cancers. To analyze the distribution of micrometastasis, a total of 1542 lymph nodes obtained from 46 patients with pN0 submucosal cancer were immunohistochemically examined by cytokeratin antibody. Sentinel node mapping was performed in 23 patients with clinical T1 tumors. The location of lymph node metastasis in the 22 patients with solitary lymph metastasis in superficial cancer was limited to recurrent nerve nodes in the upper thoracic esophagus, recurrent nerve nodes, paraesophageal nodes, or perigastric nodes in the middle or lower thoracic esophagus. For eight patients with lymph node micrometastasis in pN0 patients with superficial esophageal cancer, the locations of micrometastasis were similar to those of solitary metastasis. In sentinel node mapping, all nodal metastasis was included in sentinel nodes with a single exception. Individual lymphadenectomy in superficial ESCC will be established using methods such as analysis of past data, clinical diagnosis of lymph node metastasis by imaging, and sentinel node navigation surgery, including the diagnosis of micrometastasis.

Evaluation of Sentinel Node Concept in Gastric Cancer Based on Lymph Node Micrometastasis Determined by Reverse Transcription-Polymerase Chain Reaction

To determine the adequacy of sentinel node (SN) concept based on micrometastasis using immunohistochemistry (IHC) and reverse transcription-polymerase chain reaction (RT-PCR) in gastric cancer. The SN concept has recently been introduced in gastrointestinal tract cancers. The precise detection of lymph node metastasis including micrometastasis is important for SN navigation surgery. Sixty-one patients with gastric cancer who were preoperatively diagnosed with T1-T2 (cT1-T2) and N0 (cN0) were enrolled. They underwent standard radical gastrectomy with lymph node dissection. One day before surgery, 4 mCi of (99m)Technetium-tin colloid was endoscopically injected into the submucosa around the tumor. During surgery, radioisotope uptake in the lymph node was measured using Navigator GPS. All dissected lymph nodes were examined by RT-PCR in addition to hematoxylin and eosin staining and IHC. Sentinel nodes were identified in all patients (100%). The incidences of metastasis determined by hematoxylin and eosin and IHC were 8.2% (5 of 61) and 13.1% (8 of 61), respectively. Micrometastases undetectable by IHC were identified in 14 patients (23.0%) by RT-PCR. Only 1 patient had micrometastasis detectable by RT-PCR in lymph nodes other than SN, but this patient had a cT2 tumor. In patients with cT1 and cN0 tumors, the false negative and accuracy rates were 0% and 100%, respectively. Although the incidence of micrometastasis detected by RT-PCR was quite high, SN navigation identified such metastasis in all patients except one. Thus, the SN concept was applicable to patients with cT1 and cN0 gastric cancer, even when micrometastasis was detectable by RT-PCR.

Sentinel lymphoscintigraphy in patients with breast cancer undergoing excisional biopsy

Some small tumors of the breast cannot be diagnosed by needle biopsy, and an excisional biopsy is occasionally needed for the diagnosis. Sentinel node navigation surgery is frequently suitable for patients with such small breast cancers. The purpose of this study was to compare sentinel lymphoscintigrams in breast cancer patients who had previously undergone excisional biopsy with sentinel lymphoscintigrams in patients undergoing no excisional biopsy. We also investigated the possibility of clinical application of the sentinel node navigation procedure in the former group of patients. Sentinel lymphoscintigrams of 43 patients with breast cancer undergoing excisional biopsy were compared to those of 116 patients without excisional biopsy. Lymphoscintigrams were obtained by using intradermal and/or subdermal injections of technetium-99m labeled phytate at 2 points on each side of the dermal incision in patients after excisional biopsy. Injections were performed at 2 points of the skin over the tumor in the patients who had not undergone excisional biopsy. Axillary lymph nodes were visualized in 42 of 43 patients undergoing excisional biopsy (98%) and in 115 of 116 patients without excisional biopsy (99%). The number of visualized axillary nodes was 1 to 5 (mean +/- SD = 2.1 +/- 1.0) and 1 to 5 (mean +/- SD = 1.9 +/- 1.0) in the two groups, respectively. No significant difference was determined between the two groups. Parasternal lymph nodes were depicted in 3 patients after excisional biopsy who had the tumor in the outer half of the breast, in contrast to 4 without excisional biopsy who had the tumor in the inner half. Intramammary hot spots were observed in 5 patients after excisional biopsy and in 2 without excisional biopsy. Lymphatic vessels were observed in 23 patients (53%) who had the excisional biopsy, and in 37 (32%) who did not have the biopsy. The former figure was significantly higher than the latter (p < 0.02). Sentinel node navigation surgery for axillary nodes was shown to be possible in patients undergoing excisional biopsy. However, the visualization of parasternal nodes, intramammary hot spots and lymphatic vessels tended to increase in number, and care must be exercised in the management of these patients.

Nano‐sized fluorescent particles as new tracers for sentinel node detection: Experimental model for decision of appropriate size and wavelength

The concepts of made-to-order and low-invasiveness medicines are becoming widely accepted. A treatment for cancer, with minimum invasive surgery and without lymph nodes dissection based on sentinel lymph node (SN) navigation surgery, would adhere to these concepts. Dyes and/or radioisotopes are employed for SN detection in standard methods, however, each detection method has advantages and disadvantages. To make up for the disadvantages, we aimed at developing a new non-invasive method using fluorescent beads of uniform nano-size that could efficiently visualize SN from outside the body, and conducted experiments to determine the appropriate size and fluorescent wavelength. We examined various bead sizes and fluorescent wavelengths. The sizes were 20, 40, 100 and 200 nm. The fluorescent peak wavelengths of the beads were yellow-green (515 nm), dark red (680 nm), far red (720 nm) and infrared (755 nm). The beads were subcutaneously injected into the foot pad of the hind leg of a rat, and followed by laser scanning of the inguinal area for fluorescence observation. The beads exhibited different times for the fluorescence detection according to their sizes and wavelength. The 40 nm beads were considered to be the most appropriate size for SN detection in rats. The wavelength of near infrared was effective for avoiding attenuation by the tissue. In conclusion, we confirmed that uniformly nano-sized fluorescent beads have the potential to be an alternative to existing tracers in the detection of the SN in animal experiments if we select the appropriate particle size and wavelength.

Sentinel Node Imaging of Laryngeal Cancer Using a Portable Gamma Camera With CdTe Semiconductor Detectors

Abstract: A 59-year-old man with laryngeal cancer was scheduled to receive sentinel lymph node (SLN) navigation surgery. Radioactive colloids were endoscopically injected around the tumor. Three hours after injection, preoperative lymphoscintigraphy was performed using a new portable CdTe semiconductor camera as well as a conventional gamma camera. The semiconductor camera successfully identified an SLN neighboring the primary tumor over an acquisition time of only 30 seconds, whereas the conventional camera could not clearly visualize the SLN over the same acquisition time. This semiconductor camera also imaged the SLN in the operating room, 19 hours after the injection.

Detection of sentinel nodes and micrometastases using radioisotope navigation and immunohistochemistry in patients with gastric cancer

Patients with early gastric cancer may be treated by minimally invasive surgery. This study investigated the value of sentinel node (SN) navigation surgery, including detection of micrometastases, in patients with clinical (c) T1 and T2 gastric cancer. The day before surgery (99m)Tc-radiolabelled tin colloid was injected submucosally near the tumour. After resecting the stomach, radioisotope uptake in all dissected lymph nodes was measured during and after surgery. Micrometastasis was detected immunohistochemically using an anticytokeratin antibody. SNs were identified in 99 of 104 patients. The rate of identification of SNs in patients with cT1 and cT2 tumours, excluding three technical failures, was 99 and 95 per cent respectively. Lymph node metastases and/or micrometastases were found in 28 patients (15 cT1 and 13 cT2). In the 15 patients with cT1 tumours, at least one SN contained metastasis and/or micrometastasis. For cT1 tumours, the sensitivity and accuracy of detecting SNs were both 100 per cent. Six patients with cT2 tumours had false-negative results. SN navigation surgery appears to be clinically useful only for cT1 tumours. Based on SN results, the extent of lymphadenectomy may be reduced in patients with early gastric cancer.

Minimally invasive surgery for gastric cancer — toward a confluence of two major streams: a review

The minimalization of therapeutic invasiveness in order to preserve quality of life (QOL) is a major topic in the management of early gastric cancer. After laparoscopic surgery for gastric cancer was introduced by Kitano et al. in 1991, an enthusiasm to develop laparoscopic procedures has grown steadily. In the initial phase, early gastric cancer limited to the mucosal layer with no risk of lymph node metastasis was treated by laparoscopic wedge resection or intragastric mucosal resection. Since technical and instrumental advances in endoscopic treatment were achieved by gastroenterologists, these cases can be managed by intraluminal endoscopic approaches. The attention of surgeons then shifted to more radical procedures such as laparoscopic gastrectomy with lymph node dissection, which is comparable to open surgery and can be indicated even in advanced cancer. Although this paradigm shift has already been realized in the field of colorectal surgery, we must pay attention to the particular biological nature of gastric cancer in terms of the potential of peritoneal dissemination. While early-phase recovery after surgery has been improved by laparoscopic surgery, preservation of late-phase QOL by function-preserving surgery is also essential in this regard; therefore, the sentinel node (SN) concept has been a much-discussed topic in gastric cancer surgery to approach this aspect. Recently, the validity of the SN concept has been demonstrated by a number of single institutional studies, and prospective multicenter trials are currently ongoing. Theoretically, various types of function-preserving surgery could be applied in cases of early gastric cancer with negative SNs as less invasive surgery to improve long-term QOL. Although we still have to solve several remaining issues in the treatment of gastric cancers, a confluence of these two major streams, laparoscopic surgery and sentinel node navigation surgery, would enable us to apply a novel individualized minimally invasive approach, both in terms of degree of incisional access and extent of function preservation.

口腔咽頭癌Ｎ０症例に対するセンチネルリンパ節―症例の総括と有用性，問題点―

We assessd the feasibility and problems associated with sentinel lymph node (SLN) study in 13 cases of oral and pharyngeal squamous cell carcinoma (SCC) that were neck-node-negative clinically. The primary sites were the tongue (n = 10), other sites in the oral cavity (n = 2), and the mesopharynx (n = 1). The day before surgery, tracer was injected into the submucosa around the tumor, and scintigraphic images were acquired 2 hours later. The SLN was identified intraoperatively with a handheld gamma probe, and neck dissection, including the SLNs, was performed. Radioactivity within the nodes was confirmed with a well type scintillation counter, and all resected lymph nodes were histologically examined for metastasis. The SLN was identified in every case. There were regional lymphnode metastases in 4 cases, and metastasis to the SLNs was present in all of 4 cases. Thus, the SLN concept was valid for head and neck SCC, sentinel node navigation surgery (SNNS) was thought to be applied in stage NO SCC of the head and neck. If SNNS is performed, about 70% of patients do not require neck dissection. SNNS is feasible and cost-effective in these cases. We used two different tracers: phytate and tin colloid, and found that phytate was more useful. To avoid the effects of the shine-through phenomenon, it was thought that some directions of lymphoscintigram should be taken. For intraoperative identification of the SLNs, care should be taken to the angle of gamma probe. SLN study leads to clarify each patient's lymphoid flow mapping, and it is also useful to determine the dissection area of selective neck dissection.

Genetic Diagnosis of Oral Cancer (From Diagnosis to Therapy)

Five-year survival rates of oral cancer are not improving in spite of the progression of multidisciplinary treatment, because distant metastasis is the major cause of death in individuals suffering cancer. Therefore, early detection of metastasis at cervical lymph nodes and choosing appropriate treatment for advanced cases are highlighted for reducing deaths due to oral cancer and keeping QOL after treatment. First, actual condition of the micrometastasis in the cervival lymph nodes was analyzed with semiserial sectioning and its detection rate was improved with genetic diagnosis. SCC antigen mRNA is found to be a suitable marker of oral cancer. Next, I applied the sentinel node navigation surgery using intraoperative real-time genetic diagnosis. In order to further improve diagnostic accuracy, an optimal gene marker set was identified by means of a whole genome- wide microarray gene-expression profiling, which can detect common upregulated and downregulated genes in oral cancer. I believe that the genetic diagnosis is pivotal for choosing appropriate treatment, especially for individuals diagnosed with oral cancer.

Is a Lymph Node Detected by the Dye-Guided Method a True Sentinel Node in Gastric Cancer?

A sentinel node is defined as the initial lymph node, to which cancer cells metastasize from a primary tumor. Recently, sentinel node navigation surgery has been done using the dye-guided method. However, no study has shown that a lymph node detected by the dye-guided method is the true sentinel node from the viewpoint of micrometastasis. Micrometastases of lymph nodes, in which no metastasis was found by H&E staining, were examined to establish whether a lymph node detected by the dye-guided method is the true sentinel node. Isosulfan blue was injected endoscopically as the dye-guided method at a submucosal lesion of early gastric cancer. Total 345 lymph nodes, including 150 blue-dyed lymph nodes and 195 nondyed lymph nodes were collected from 57 patients and each was quartered. Two quarters were examined histologically by H&E staining and cytokeratin staining. The other specimens were used for quantitative reverse transcription-PCR of CEA and CK20 mRNAs. Lymph node disease was not found in any of 345 lymph nodes from the 57 patients by routine H&E staining. By contrast, either CEA or CK20 mRNA expression was detected in 21 of 345 lymph nodes obtained from the 10 (18%) of 57 patients by quantitative reverse transcription-PCR. Eight of the 21 micrometastasis-positive lymph nodes were confirmed to be positive for cytokeratin staining. Although micrometastasis of nondyed lymph nodes was found in three cases, these were included in the 10 cases with micrometastasis of blue-dyed nodes, such that there was no patient who only had micrometastasis in nondyed nodes. Six of 10 cases were micrometastasis-positive in a single node; all six were blue-dyed nodes. A lymph node detected by the dye-guided method should be a true sentinel node to which cancer cells metastasize initially.

Sentinel node detection in n0 laryngeal cancer

Problem: Sentinel lymph node (SLN) is the lymph node that directly receives lymphatic flow from a primary cancer lesion. Attention has been focused on the SLN concept, which implies that lymphatic metastasis initially occurs at SLN. In SLN navigation surgery, lymph node dissection beyond SLN can be omitted if SLN is metastasis free. Favorable outcomes are reported for malignant tumors such as breast cancer, malignant melanoma, and gastrointestinal cancer, and the application of this concept to other types of cancer is anticipated. In this study, the implications of the SLN concept on laryngeal cancer were investigated by measuring the feasibility of determining indications for neck dissection according to the presence of metastasis to SLN. Methods: Eleven patients suffering from laryngeal cancer staged T2 or higher and clinically N0 were enrolled in this study. Ninety-nine mTc-phytate (74MBq/mL) was injected submucosally by 0.2 mL into the several sites adjacent to the tumor using endoscope on the day preceding surgery. The lymphoscintigrams were performed 2 hours after injection. SLNs were surveyed using a gamma probe immediately prior to incision and during neck dissection. Histopathological examinations were performed on the resected lymph nodes. Results: One to three SLNs were confirmed by preoperative lymphoscintigraphy and intraoperatively by gamma probe in all of the cases. The pathological evaluation of SLNs revealed that 4 cases had subclinical metastasis, showing consistency with the sentinel node concept. In other 7 cases, metastasis to SLN as well as to other lymph nodes was negative, reflecting the correct lymph node status. No false-negative results were observed. Conclusion: Although more cases need to be studied in order to determine the feasibility of applying the SLN concept to laryngeal cancer, so far all cases were consistent with the sentinel node concept. Significance: SLN detection may be useful for determining indications for neck dissection in N0 laryngeal cancer. Support: None reported.

Particle size of tin and phytate colloid in sentinel node identification 1

Background Sentinel node navigation surgery (SNNS) has recently been introduced for various types of carcinoma. Numerous radioisotopes are used as tracers for SNNS. However, few reports have examined particle sizes of isotope colloids used in SNNS. Materials and methods Tin and phytate colloids were used in the present study. Isotonic sodium chloride and tin solutions were mixed ratios of 1:4, 1:2, 1:1, 2:1, and 4:1. Calcium solution and Tc-phytate were mixed at ratios of 1:4, 1:2, 1:1, 2:1 and 4:1. Particle size was measured using a Coulter Model N4SD Sub-micron Particle Analyzer. Results When isotonic sodium chloride and tin solutions were mixed at ratios of 1:4, 1:2, 1:1, 2:1, and 4:1, particle size was 47 ± 9, 96 ± 10, 712 ± 83, 925 ± 66 and 1079 ± 132 nm, respectively. As the ratio of tin solution decreased, colloid particle size increased. Particle size of phytate colloid varied from 174 ± 39 nm to 1222 ± 283 nm, according to calcium concentration. Phytate colloid particle size became larger as the ratio of phytate solution decreased. Conclusions We ascertained that the particle size of tin and phytate colloids is controllable by manipulating the conditions under which the colloids form. These results will offer useful information when SNNS is performed.

Sentinel node navigation surgery using indocyanine green in patients with lung cancer.

To investigate the potential use of sentinel node navigation surgery (SNNS) using indocyanine green (ICG) in lung cancer. The subjects were 38 patients with stage cN0 lung cancer. After thoracotomy, we injected 5 ml ICG and 400 U hyaluronidase around the tumor, and identified the stained lymph nodes (LNs) intraoperatively by inspection. Postoperatively, we measured ICG concentrations in the dissected LNs. Lymph nodes with an ICG concentration of more than 1.5 times the mean were defined as sentinel nodes (SNs). There were 30 pN0, 6 pN1, and 2 pN2 cancers. The tumor size ranged from 11 to 75 (mean 31 +/- 15) mm. Sentinel nodes were identified by inspection in 7 (18.4%) of the 38 patients. Lymphatic mapping with ICG concentration was successful in 38 (100%) of 38. One SN was found in 18 patients and two SNs were found in 20. The SN predicted the status of metastasis of all LNs in 37 (97%) of 38. Metastases were identified in the SN alone in 5 (62.5%) of 8. There was one false negative, caused by a metastatic LN being occupied by tumor cells. These findings support the efficiency of SNNS for clinically node-negative lung cancer.

In vivo identification of sentinel lymph nodes for clinical stage I non-small cell lung cancer for abbreviation of mediastinal lymph node dissection

Background: We previously reported that an identification of sentinel lymph node (SN) with a techenetium-99m ( 99 m Tc ) tin colloid by ex vivo counting, i.e. the radio-activity of dissected lymph nodes, was a reliable method of establishing the first site of nodal metastasis in non-small cell lung cancer [J. Thorac. Cardiovasc. Surg. 124(2002)486]. However, for SN navigation surgery, SN should be identified before lymph node dissection (in vivo) but not after that (ex vivo). In order to reduce mediastinal lymph node dissection for clinical stage I non-small cell lung cancer (NSCLC) by SN navigation surgery, the SN identifications for hilar lymph nodes by ex vivo counting, and for mediastinal lymph nodes by in vivo, were evaluated. Methods: Intra-operative SN identification using 99 m Tc tin colloid was conducted on 104 patients with clinical stage I NSCLC who had had major lung resections with mediastinal lymph node dissections. The hilar SNs were identified by ex vivo counting (after lung resection) and the mediastinal SNs were identified by in vivo counting (before lymph node dissection). To evaluate the accuracy of mediastinal SN identification by in vivo counting, it was compared with the data by ex vivo counting. Results: SNs were identified in 84 patients (81%). SNs were identified at the hilum by ex vivo counting in 78 patients (93%) and at the mediastinum by in vivo counting in 40 patients (48%). While 15 patients had lymph node metastases, i.e. N1 in six and N2 in nine, the SNs could be found to have metastases during operation in 13 of the 15 patients (87%). The in vivo counting of the mediastinum missed out the mediastinal SNs identified by ex vivo counting in four of the 84 patients (5%). Conclusion: If the hilar SNs identified by ex vivo counting and the mediastinal SNs identified by in vivo counting had no metastases, then mediastinal lymph node dissection could be abbreviated for patients with clinical stage I NSCLC.

Intraoperative real-time genetic diagnosis for sentinel node navigation surgery

Sentinel node navigation surgery (SNNS) has received considerable attention for its role in deciding whether to perform neck dissection in patients with early oral cancer. However, diagnostic accuracy and its intraoperative availability of results remain important concerns. First, we shortened the examination time required for genetic diagnosis. Second, we assessed the quality of the extracted mRNA. Third, 10 patients with early N0 oral cancer underwent SNNS, using our new technique for genetic diagnosis to determine whether neck dissection was required. The examination time of our one-step reverse-transcriptase polymerase chain reaction method using a minicolumn and LightCycler was successfully shortened to 2 h, permitting intraoperative genetic diagnosis. The extracted mRNA was of high quality. Six sentinel nodes in four patients were diagnosed to be metastatic on genetic diagnosis; these patients underwent neck dissection. The other six patients avoided unnecessary surgery. We conclude that intraoperative genetic diagnosis of micrometastasis holds promise of being a sensitive method that can be used to support SNNS.

Sentinel nodes of malignancies originating in the alimentary tract.

The feasibility of the sentinel node concept for malignancies originating in the alimentary tract is attracting much interest among researchers in the field of gastrointestinal oncology. We have tested more than 350 such cases and obtained favorable and promising initial results. The detectability of sentinel nodes using endoscopically injected Tc-99m tin colloid for these tumors exceeded 90%. Although the false negative ratio was not so low (approximately 10%), most of these cases had an inaccurate preoperative evaluation of mural invasion and/or a technically unfavorable injection. When the indication is restricted to patients with early-stage disease, and when the radioactive colloid is properly administered, sentinel node navigation therapy would be applicable for gastrointestinal malignancies. To achieve successful sentinel node navigation surgery it is essential to accurately identify sentinel nodes, and lymphoscintigraphy is a very useful test to confirm the location of sentinel nodes preoperatively. However, image processing is required for lymphoscintigrams because the original image depicts only high activity at the injection site and faint radioactivity in the sentinel nodes. We have clearly imaged the silhouette of the body using Compton scattered photons, and have also proposed several methods to improve the contrast between the injection sites and sentinel nodes. Many sentinel nodes can be clearly visualized by subtraction of the background activity with heterogeneous distribution. The development of the portable gamma camera, enabling intraoperative imaging, also contributes to less invasive biopsy of sentinel nodes. We have obtained promising initial results using a portable imaging device with semiconductor detectors. These promising results suggest that sentinel node navigation therapy including radiotherapy will be a new therapy for early-stage gastrointestinal malignancies in the near future, with nuclear medicine contributing to the establishment of new, less invasive therapies for gastrointestinal cancer.

Sentinel lymph node navigation surgery for pancreatic head cancers

Recently, sentinel lymph node (SN) concept has been validated for gastrointestinal and breast cancers. Our previous study has shown that the No. 13 posterior pancreaticoduodenal lymph node group constitutes the major regional drainage site from primary tumors in the pancreatic head, and that the status of these nodes predicts that of the No. 16 abdominal paraaortic lymph node group. Based on these results, we have developed SN navigation surgery for pancreatic cancer, in the search for more curable and less invasive surgery. In brief, 2% patent blue dye is injected into the peritumoral area. Approximately 5 min later, one or more blue-stained nodes within the area of the No. 13 lymph node group are identified and excised for intraoperative frozen section examination. The subsequent surgical decision-tree is as follows: i) if No. 13 SNs are negative, an extended No. 16 lymph node dissection is not performed to reduce morbidity, and ii) when cancer is found, the No. 16 lymph nodes are dissected completely. Since July 1997, nine of 21 patients scheduled to undergo an extended curative surgery underwent SN biopsy. SNs within the area of the No. 13 lymph node group were identified in 8 (89%) patients. An extended No. 16 lymph node dissection was avoided in 4 SN-negative patients. The overall 3-year survival rate of the 21 patients was 36%, and 4 patients (three SN-negative and one SN-positive patients) with stage IVa disease were alive 3 years after surgery. Three SN-negative patients underwent an extended curative pylorus-preserving pancreaticoduodenectomy (PpPD) with combined portal vein resection, but without an extended No. 16 dissection. In conclusion, SN biopsy and curative PpPD can increase curability, reduce morbidity, and provide long-term survival in patients with locally advanced pancreatic head cancer as an alternative to routine extended No. 16 lymph node dissection.

Sentinel node navigation surgery の現況と展望

Sentinel node navigation surgery の現況と展望