Sentinel lymph node biopsy for gastrointestinal cancers

A dual modal silver bumpy nanoprobe for photoacoustic imaging and SERS multiplexed identification of in vivo lymph nodes

Multimodal imaging can provide complementary biomedical information which has huge potential in pre-clinical and clinical imaging and sensing. In this study, we introduce dual modal NIR silver bumpy nanoprobes for in vivo imaging and multiplexed detection of biomolecules by both photoacoustic imaging (PAI) and surface-enhanced Raman scattering (SERS) techniques. For this study, we used silica-coated silver bumpy nanoshell probes (AgNS@SiO₂). AgNS@SiO₂ have strong NIR-absorption and scattering properties compared with other nanostructures, and therefore, can be a good candidate for photoacoustic (PA) and SERS multimodal imaging. We obtained PA images of the skin and SLNs of rats by injecting various kinds of Raman-labeled AgNS@SiO₂. Multiplexed identification of the injected AgNS@SiO₂ was achieved by measuring SERS signals. AgNS@SiO₂ have the potential to be applied in detecting cancer biomarkers by locating biomarkers quickly using PA imaging, and identification by multiplexed target measurement using SERS signals in vivo.

Fluorescent iodized emulsion for pre- and intraoperative sentinel lymph node imaging: validation in a preclinical model

PURPOSE

To validate the usefulness of a newly developed tracer for preoperative gastric sentinel lymph node (LN) (SLN) mapping and intraoperative navigation after a single preoperative submucosal injection in rat and beagle models.

MATERIALS AND METHODS

This study was approved by the Experimental Animal Ethical Committee of Yonsei University College of Medicine according to the eighth edition of the Guide for the Care and Use of Laboratory Animals published in 2011. An emulsion was developed that contained indocyanine green in iodized oil, which can be visualized with both computed tomography (CT) and near-infrared (NIR) optical imaging and has the property of delayed washout. This emulsion was injected into the footpad of rats (n = 6) and the gastric submucosa of beagles (n = 8). CT lymphography was performed. The degree of enhancement of popliteal LNs was measured in rats, and the enhancing LNs were identified and the degree of enhancement of the enhancing LNs was measured in beagles. Next, NIR imaging was performed in beagles during open, laparoscopic, and robotic surgery to identify LNs containing the fluorescent signals of indocyanine green. The enhanced LNs detected with CT lymphography and NIR imaging were matched to see if they corresponded.

RESULTS

Preoperative CT lymphography facilitated SLN mapping, and 26 SLNs were identified in eight beagles. NIR imaging enabled high-spatial-resolution visualization of both SLNs and the intervening lymphatic vessels and was useful for intraoperative SLN navigation.

CONCLUSION

SLN mapping with fluorescent iodized oil emulsion is effective and feasible for both CT and NIR imaging.

In vivo lymph node mapping by Cadmium Tellurium quantum dots in rats

BACKGROUND

Intraoperative lymph node mapping (LNM) is highly significant for many surgeries in patients with cancer. Many types of tracers are currently used, but the ideal method has not yet been identified. We aimed to identify a stable lymphatic drainage pathway in an animal model and compared the effects of quantum dots (QD), a new fluorescent tracer, with those of methylene blue in intraoperative LNM.

MATERIALS AND METHODS

Indian ink (0.2 mL) was subcutaneously injected into the plantar metatarsal regions of six Sprague-Dawley rats. After 2 wk of incubation and subsequent dissection, the potentially stained LNs were examined pathologically to identify the lymphatic drainage pathway. After applying anesthesia, 0.1 mL methylene blue (2%) and QD (1 mg/mL) were injected into the plantar metatarsal regions of six rats for intraoperative LNM. The QD group was observed with a near-infrared imaging system, and the methylene blue group was directly observed. Drainages were recorded at 5, 10, 30, 60, and 120 min and at 1 d.

RESULTS

Two three-level drainage pathways, that is, a peripheral drainage (popliteal LNs, inguinal LNs, and axillary LNs) and a central drainage (popliteal lymph node [LN], iliac LN, and renal LN) pathways were identified. Both methylene blue and QD stained the sentinel lymph node (SLNs) quickly, but methylene blue was difficult to identify in the deep tissues and the LNs beyond the SLN. Furthermore, the blue-stained LNs remain dyed for only 2 h. In contrast, the QDs exhibited high target-to-background ratios in both the SLNs and the following LNs. Additionally, the fluorescence lasted from 5 min-1 d after injection.

CONCLUSIONS

An ideal lymphatic drainage model was found. QDs are excellent tracers for intraoperative LNM compared with methylene blue. Near infrared fluorescent imaging is a promising LNM method for clinical practice.

Clinical relevance of novel imaging technologies for sentinel lymph node identification and staging

The sentinel lymph node (SLN) concept has become a standard of care for patients with breast cancer and melanoma, yet its clinical application to other cancer types has been somewhat limited. This is mainly due to the reduced accuracy of conventional SLN mapping techniques (using blue dye and/or radiocolloids as lymphatic tracers) in cancer types where lymphatic drainage is more complex, and SLNs are within close proximity to other nodes or the tumour site. In recent years, many novel techniques for SLN mapping have been developed including fluorescence, x-ray, and magnetic resonant detection. Whilst each technique has its own advantages/disadvantages, the role of targeted contrast agents (for enhanced retention in the SLN, or for immunostaging) is increasing, and may represent the new standard for mapping the SLN in many solid organ tumours. This review article discusses current limitations of conventional techniques, limiting factors of nanoparticulate based contrast agents, and efforts to circumvent these limitations with modern tracer architecture.

[Lymph node staging in gastrointestinal cancer. Combination of methylene blue-assisted lymph node dissection and ex vivo sentinel lymph node mapping]

The histopathological lymph node staging is of crucial importance for the prognosis estimation and therapy stratification in gastrointestinal cancer. However, the recommended numbers of lymph nodes that should be evaluated are often not reached in routine practice. Methylene blue assisted lymph node dissection was introduced as a new, simple and efficient technique to improve lymph node harvest in gastrointestinal cancer. This method is inexpensive, causes no delay and needs no toxic substances. All studies performed revealed a highly significantly improved lymph node harvest in comparison to the conventional technique. Moreover, this technique can be combined with a new ex vivo sentinel lymph node mapping that for the first time is based on histological sentinel lymph node detection. The success rate of this method is similar to conventional techniques and it enables an efficient application of extended investigation methods, such as immunohistochemistry or the polymerase chain reaction.

Real-time mapping of rat stomach lymph nodes by quantum dots

OBJECTIVE

To develop a real-time imaging method to identify the rat stomach lymph node basin with quantum dots (Qdots).

MATERIAL AND METHODS

Six Sprague-Dawley rats received injections of 0.05 ml Qdots (1 mg/ml) in the subserosal layer in the lesser curvature of the gastric antrum. Subsequently, draining lymphatic channels and lymph nodes were visualized with a near-infrared fluorescence imaging system. Histological examination was required to confirm the presence of lymph nodes. Additionally, rats received injections of Qdots and underwent 2 weeks of observation to confirm if there was any abnormality. The distribution of Qdots was measured by inductively coupled plasma-mass spectrometry.

RESULTS

After injection of the Qdots, the gastric sentinel lymph nodes were visualized 15 min later. The fluorescence then began to spread. The intensity of fluorescence increased in the perigastric area at 60 min, and declined at 360 min. Histological analysis of the fluorescent tissue confirmed the presence of nodal tissue. The results of a cadmium assay showed that Qdots were mainly distributed in the liver, spleen and kidney of the rats. No apparent toxicity could be seen during the 2 weeks of observation.

CONCLUSIONS

NIR fluorescence imaging of lymph nodes with Qdots is a novel and reliable real-time technique that can be used to assist with identification and resection of stomach lymph nodes. The optimal observation time of perigastric SLNs was 15 min after the injection, and the optimal observation time of perigastric lymph nodes beyond the SLNs was 60-120 min after the injection.

Nanoscale iodized oil emulsion: a useful tracer for pretreatment sentinel node detection using CT lymphography in a normal canine gastric model

BACKGROUND

Pretreatment identification of the sentinel lymph nodes (SLNs) in gastric cancer patients may have great advantages for minimally invasive treatment. No reliable method for the detection of SLNs during the pretreatment period in gastric cancer has been established. The aim of this study was to determine whether computed tomographic (CT) lymphography using nanoscale iodized oil emulsion via endoscopic submucosal injection can visualize LNs.

METHODS

Five dogs underwent CT lymphography after endoscopic submucosal injection of 2 ml of a nanoscale iodized oil emulsion. CT images were taken before and 30, 90, and 210 min after contrast injection. Intraoperative SLN detection was performed using endoscopically injected indocyanine green lymphography for comparison.

RESULTS

Computed tomographic lymphography with nanoscale iodized oil emulsion enabled the visualization of 19 enhanced LNs (mean = 3.8/dog, range = 3-6) with a 100% SLN detection rate. The locations of the SLNs were the lesser curvature (n = 7), greater curvature (n = 1), infrapyloric (n = 3), and left gastric (n = 8) areas. Contrast enhancement of SLNs continuously increased and peaked after 210 min at 142.4 ± 42.3 HU. No green LNs were visualized in the three locations that were detected by CT lymphography. However, no additional LNs were visualized using the dye method. The concordance rate based on the LNs between the SLNs on CT lymphography and the green LNs using the ICG method was 84% (16/19), whereas the concordance rate of the stations identified by CT lymphography and the dye method was 78.6% (11/14).

CONCLUSIONS

Computed tomographic lymphography using nanoscale iodized oil emulsion is a promising tool for preoperative SLN detection for early gastric cancer if the biological safety of the nanoscale iodized oil emulsion can be established.

Nuclear beta-catenin overexpression in metastatic sentinel lymph node is associated with synchronous liver metastasis in colorectal cancer

BACKGROUND

Beta-catenin, a component of the Wingless/Wnt signaling pathway, can activate target genes linking with the adenomatous polyposis coli (APC) gene in colorectal cancer. The purpose of this study is to investigate whether nuclear beta-catenin overexpression in metastatic sentinel lymph node(s) [SLN(s)] is associated with synchronous liver metastasis.

METHODS

Clinicopathological data from 355 patients (93 cases with liver metastasis and 262 cases without liver metastasis) were reviewed. Beta-catenin expression in metastatic SLN(s) and liver metastatic lesions was examined by immunohistochemistry. The association of nuclear beta-catenin expression in metastatic SLN(s) and liver metastatic lesions was evaluated, and the relationship between nuclear beta-catenin expression and clinicopathological characteristics was analyzed. Finally, univariate and logistic multivariate regression analyses were adopted to discriminate the risk factors of liver metastasis.

RESULTS

Nuclear beta-catenin overexpression in metastatic SLN(s) was observed in 70 patients with liver metastasis and 31 patients without liver metastasis (75.3% vs. 11.8%; P < 0.001). Nuclear beta-catenin expression was noted in all the metastatic lesions. Spearman rank correlation analysis demonstrated that nuclear beta-catenin expression in metastatic SLN(s) had a positive correlation with that in metastatic lesions (r = 0.425, P < 0.001). Univariate and multivariate analyses indicated that nuclear beta-catenin overexpression in metastatic SLN(s) correlated with liver metastasis.

CONCLUSIONS

Nuclear beta-catenin overexpression in metastatic SLN(s) is strongly associated with liver metastasis and may contribute to predict liver metastasis.

Diagnostic value of sentinel lymph node biopsy in gastric cancer: a meta-analysis

BACKGROUND

The possible application and validity of the sentinel lymph node (SLN) concept in gastric cancer (GC) is still debated. A systematic review to evaluate the diagnostic value of SLN biopsy (SLNB) in GC is urgently needed.

METHODS

A systematic review of relevant literatures was performed in PubMed, Embase, and The Cochrane Library. A random-effect model was used to pool the data, and subgroup analysis was used to explain the heterogeneities.

RESULTS

A total of 38 included studies (2,128 patients) were included. The pooled SLN identification rate, sensitivity, negative predictive value, and accuracy were 93.7% (95% confidence interval [95% CI]: 91.1-95.6%), 76.9% (95% CI: 71.6-81.4%), 90.3% (95% CI: 86.9-92.9%), and 92.0% (95% CI: 89.9-93.7%), respectively. Subgroup analysis showed that early T stage, combined tracers, submucosal injection method, conventional open surgery, and usage of immunohistochemistry were associated with higher SLN identification rate and sensitivity.

CONCLUSIONS

SLNB in GC is technically feasible with an acceptable sensitivity. However, further studies are needed to confirm the best procedure and standard criteria.

The clinical use of indocyanine green as a near-infrared fluorescent contrast agent for image-guided oncologic surgery

Optical imaging using near-infrared (NIR) fluorescence provides new prospects for general and oncologic surgery. ICG is currently utilised in NIR fluorescence cancer-related surgery for three indications: sentinel lymph node (SLN) mapping, intraoperative identification of solid tumours, and angiography during reconstructive surgery. Therefore, understanding its advantages and limitations is of significant importance. Although non-targeted and non-conjugatable, ICG appears to be laying the foundation for more widespread use of NIR fluorescence-guided surgery.

High FOXP3+ regulatory T-cell density in the sentinel lymph node is associated with downstream non-sentinel lymph-node metastasis in gastric cancer

Background:

We aimed to evaluate the immunologic nature of sentinel lymph nodes (SLNs) in gastric cancer patients and to determine whether it can predict non-SLN metastasis.

Methods:

Sentinel lymph node samples were collected from 64 gastric carcinoma patients who had undergone gastrectomy with SLN biopsy. One representative SLN sample was selected from each patient and was subjected to immunostaining for CD8, CD57, FOXP3, and DC-LAMP. The numbers of marker-positive cells in each sample were counted. The relationships between various immune cell densities and clinicopathologic parameters or metastasis status of SLNs and non-SLNs were sought.

Results:

High FOXP3+ Treg density of the SLN was found to be significantly associated with the presence of metastasis in either SLNs or non-SLNs. DC-LAMP+ cell density of the SLN was the highest at the isolated tumours cell level, and this decreased along with an increase in tumour metastasis in either SLNs or non-SLNs. Univariate and multivariate logistic regression models revealed that high FOXP3+ Treg density of the SLN was an independently significant predictor of non-SLN metastasis.

Conclusions:

This study is the first to indicate an important role of SLNs in metastatic dissemination of gastric cancer. Our findings suggest that Tregs could be a new therapeutic target for regulating the metastasis of gastric cancer.

The extent of lymph node dissection for gastric cancer: a critical appraisal

The extent of lymphadenectomy during therapeutic gastrectomy for gastric cancer remains a protracted and controversial issue. While traditionally extended lymphadenectomy is performed in Eastern Asia, limited lymphadenectomy is advocated by most western surgeons. Two large western randomized trials, meta-analyses and a recent systematic review were unable to demonstrate overall benefit from extended lymphadenectomy. In this review, the currently available data on this topic are critically evaluated, while ongoing studies and future perspective are discussed.

Sentinel node biopsy in squamous-cell carcinoma of the anal canal

BACKGROUND

Radiochemotherapy is the standard treatment for patients with carcinoma of the anal canal. Therefore, a surgical specimen is not usually obtained. Inguinal lymph node metastases cannot be accurately predicted by either clinical examination or imaging techniques. In this study, we applied the sentinel node technique in patients with anal canal squamous-cell carcinoma to determine whether this provided more reliable staging of tumors.

METHODS

From May 2007 to May 2009, we enrolled 11 patients (7 women) with a mean age 65 (range 39-80) years with squamous-cell carcinoma of the anal canal and clinically and radiologically negative groin lymph nodes. The patients were staged with endorectal ultrasound, computed tomographic scan, magnetic resonance imaging of the pelvis, and positron emission tomography. There were two T1, four T2, and five T3 tumors (International Union Against Cancer classification). Lymphoscintigraphy with peritumoral 99mTc colloid injection was performed 16 to 18 h before surgery. During the surgery, patent blue dye was injected peritumorally, and the sentinel inguinal node was identified by a handheld gamma probe and dye visualization.

RESULTS

The sentinel lymph node was detected in all 11 patients by scintigraphy; in 9 cases, the lymph node was in the inguinal region. All of these patients underwent radioguided node biopsy, and a total of 12 lymph nodes were removed. The average diameter of the resected nodes was 8 (range 4-20) mm. No serious complications occurred. In three patients, metastases were identified in the lymph node.

CONCLUSIONS

Sentinel node biopsy is a more accurate method than clinical or radiological techniques to stage the disease of patients with anal carcinoma.

Preoperative imaging of sentinel lymph nodes in gastric cancer using CT lymphography

PURPOSE

Preoperative identification of the sentinel lymph node (SLN) in gastric cancer (GC) patients may have great advantages for the minimally invasive treatment. This study was performed to evaluate the possibility of preoperative SLN detection using CT lymphography.

MATERIALS AND METHODS

Fourteen patients with early GC were enrolled. CT images were obtained before and at 1, 3, and 5 minutes after endoscopic submucosal peritumoral injection of 2 mL iopamidol. For patients with clearly identified SLNs, to make comparisons with the CT lymphography results, intraoperative SLN detection was performed using subserosally injected Indocyanine green (ICG) lymphography and ex vivo ICG and iopamidol lymphography using mammography was also performed.

RESULTS

CT lymphography clearly visualized draining lymphatics and SLNs in 4 (28.6%) out of 14 patients. All clearly visualized SLNs (one to three SLNs per patient) under preoperative imaging were detected in the same location by intraoperative ICG lymphography and ex vivo ICG and iopamidol lymphography using mammography. All preoperative SLN detections were observed with the primary tumors in the lower third of the stomach.

CONCLUSION

Although our study demonstrated a SLN detection rate of less than 30%, CT lymphography with radio-contrast showed potential as a method of preoperative SLN detection for GC.

Sentinel node biopsy by indocyanine green retention fluorescence detection for inguinal lymph node staging of anal cancer: preliminary experience

BACKGROUND

There is some evidence that sentinel lymph node (SLN) biopsy guided by dye injection and/or radioisotopes can improve staging of inguinal lymph nodes (LNs) in anal cancer. This study was performed to investigate the feasibility of fluorescence detection of SLN and lymphatic mapping in anal cancer.

METHODS

Twelve patients with anal cancer without evidence for inguinal LN involvement were included in the study. Intraoperatively, all patients received a peritumorous injection of 25 mg indocyanine green (ICG) for fluorescence imaging of the SLN with a near-infrared camera. For comparison, conventional SLN detection by technetium-(99)m-sulfur radiocolloid injection in combination with blue dye was also performed in all patients. The results of both techniques and the effect on the therapeutic regimen were analyzed.

RESULTS

Overall, ICG fluorescence imaging identified at least one SLN in 10 of 12 patients (detection rate, 83%). With the combination of radionuclide and blue dye, SLN were detected in 9 of 12 patients (detection rate, 75%). Metastatic involvement of the SLN was found in 2 of 10 patients versus 2 of 9 patients. Patients with metastatic involvement of the SLN received extended radiation field with inguinal boost.

CONCLUSIONS

ICG fluorescence imaging allows intraoperative lymphatic mapping and transcutaneous SLN detection for selective biopsy of inguinal SLN in anal cancer. This technique should be further evaluated in comparative studies with larger patient numbers.

Modulated T-complex protein 1 ζ and peptidyl-prolyl cis-trans isomerase B are two novel indicators for evaluating lymph node metastasis in colorectal cancer: Evidence from proteomics and bioinformatics

Lymph node metastasis (LNM) is an important indicator for systematic therapy, which could increase the survival of colorectal cancer (CRC) patients. However, effective clinical evaluation for LNM is still absent to date. In this study, protein expression profiles of CRC tissues were compared between patients with and without LNM. Based on average expression level, 12 proteins were found to be differentially expressed in the CRC tissues with LNM, whose discrimination reliability was confirmed by PCA. With stepwise linear discriminant analysis, T-complex protein 1 ζ subunit and peptidyl-prolyl cis-trans isomerase B (PPIB) were identified as two main contributors for separating CRC tissues with positive LNM from those negative ones in both original-grouped and cross-validated-grouped cases, which was also supported in subsequent linear support vector machine analysis. In addition, the expression alterations of the two proteins were verified by Western blot and immunohistochemistry. Functional studies also confirmed the role of PPIB in migration and invasion of cancer cells. Taken together, the down-regulated T-complex protein 1 ζ subunit and up-regulated PPIB were identified as two promising indicators for the clinical evaluation of LNM in CRC patients.

Factors influencing lymph node recovery from the operative specimen after gastrectomy for gastric adenocarcinoma

BACKGROUND

Regional lymph node metastases are an important predictor of survival for patients with resectable adenocarcinoma of the stomach. Currently, the number of lymph nodes examined is frequently less than requirements for accurate staging. Clinical factors associated with lymph node recovery are understood poorly.

METHODS

We performed a retrospective chart review of 99 consecutive patients who underwent gastrectomy for gastric adenocarcinoma distal to the gastroesophageal junction to determine clinical variables associated lymph node recovery.

RESULTS

Ninety-nine patients underwent gastrectomy for gastric adenocarcinoma at our two hospitals. More than 15 lymph nodes were examined in 64% of specimens. Univariate analysis showed an association between the number of lymph nodes recovered and the number of positive nodes, lymphadenectomy extent, hospital, surgeon, and pathology technician (p < 0.001). Multivariate analysis identified the pathology technician as the most important healthcare-related variable contributing to the variation of lymph node recovery, using fixed- (p < 0.001) and random-effects models.

CONCLUSIONS

This study suggests that the pathology technician is an important healthcare-related factor influencing lymph node recovery after gastrectomy. In identifying potential areas benefiting from a systems improvements approach, focus on the technical aspects of specimen processing may be of benefit in maximizing the number of lymph nodes recovered.

Methylene blue-assisted lymph node dissection in combination with ex vivo sentinel lymph node mapping in gastric cancer

AIMS

Lymph node (LN) stage is still the strongest prognostic marker in potentially curable gastric cancer. Accuracy of histopathological lymph node assessment depends on the number of investigated LNs and detection rate of metastases and micrometastases. The aim was to perform a feasibility study employing intra-arterial methylene blue injection - a novel method to improve LN harvest - and ex vivo sentinel LN mapping.

METHODS AND RESULTS

A total of 33 cases were enrolled, including 14 retrospective cases that served as a control group. The methylene group showed a highly significant improved mean LN harvest compared with unstained cases, with 38 +/- 14 versus 21 +/- 10 LNs (P < 0.001), respectively. The detection rate of ex vivo sentinel mapping was 88%. No skip metastases occurred.

CONCLUSION

Both techniques have the potential to improve the accuracy of histopathological LN staging and can be combined successfully.

Factors associated with detection failure and false-negative sentinel node biopsy findings in gastric cancer: results of prospective single center trials

BACKGROUND AND OBJECTIVES

The factors associated with successful sentinel node biopsy (SNB) are limited in gastric cancer despite a wide range of sensitivities reported. This study was performed to identify the factors associated with detection failure and SNB false-negativity in gastric cancer.

METHODS

SNB was performed on 156 gastric cancer patients from May 2002 to April 2007 at the Korean National Cancer Center during three consecutive prospective trials. Indications for SNB were determined preoperatively in cT1-2N0 patients. Dissected SNs and non-SNs after D2 lymphadenectomy were pathologically evaluated for metastasis. Clinical, pathological, and technical factors were analyzed for detection failure and false-negativity.

RESULTS

SNs were detected in 147 patients (94.2%) and the median number of SNs detected per patient was 3 (1-12). Twenty-five of 37 with nodal metastasis were diagnosed by SNB (sensitivity, 67.6%). Surgeon's inexperience (<or=30 procedures) and a male patient gender were significantly associated with detection failure (P = 0.014 and 0.031, respectively). A small number of SNs (<or= 3) was found to be significantly associated with false-negativity (P = 0.027).

CONCLUSIONS

SNB requires experience for successful detection and should be performed cautiously in male patients. Harvesting of more than three SNs is warranted to reduce false-negatives when diagnosing nodal metastasis.

A comprehensive overview of radioguided surgery using gamma detection probe technology

The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology.

Could lymphatic mapping and sentinel node biopsy provide oncological providence for local resectional techniques for colon cancer? A review of the literature

BACKGROUND

Endoscopic resectional techniques for colon cancer are undermined by their inability to determine lymph node status. This limits their application to only those lesions at the most minimal risk of lymphatic dissemination whereas their technical capacity could allow intraluminal or even transluminal address of larger lesions. Sentinel node biopsy may theoretically address this breach although the variability of its reported results for this disease is worrisome.

METHODS

Medline, EMBASE and Cochrane databases were interrogated back to 1999 to identify all publications concerning lymphatic mapping for colon cancer with reference cross-checking for completeness. All reports were examined from the perspective of in vivo technique accuracy selectively in early stage disease (i.e. lesions potentially within the technical capacity of endoscopic resection).

RESULTS

Fifty-two studies detailing the experiences of 3390 patients were identified. Considerable variation in patient characteristics as well as in surgical and histological quality assurances were however evident among the studies identified. In addition, considerable contamination of the studies by inclusion of rectal cancer without subgroup separation was frequent. Indeed such is the heterogeneity of the publications to date, formal meta-analysis to pool patient cohorts in order to definitively ascertain technique accuracy in those with T1 and/or T2 cancer is not possible. Although lymphatic mapping in early stage neoplasia alone has rarely been specifically studied, those studies that included examination of false negative rates identified high T3/4 patient proportions and larger tumor size as being important confounders. Under selected circumstances however the technique seems to perform sufficiently reliably to allow it prompt consideration of its use to tailor operative extent.

CONCLUSION

The specific question of whether sentinel node biopsy can augment the oncological propriety for endoscopic resective techniques (including Natural Orifice Transluminal Endoscopic Surgery [NOTES]) cannot be definitively answered at present. Study heterogeneity may account for the variability evident in the results from different centers. Enhanced capacity (perhaps to the level necessary to consider selective avoidance of en bloc mesenteric resection) by its confinement to only early stage disease is plausible although not proven. Specific study of the technique in early stage tumors is clearly essential before proffering this approach.