Is sentinel lymph node mapping in colorectal cancer a future prognostic factor? A meta-analysis

Ex vivo sentinel lymph node investigation in colorectal cancer

Introduction In Brazil, about 26,000 cases of colorectal cancer are diagnosed per year. Pa- tients considered at the early stage of disease (without lymph node) evolve with tumor relapse or recurrence in up to a quarter of cases, probably due to understaging.

Objective Research on ex vivo sentinel lymph node in patients with colorectal adenocarcinoma.

Materials and methods We studied 37 patients who underwent curative surgical resection. The marker used to identify lymph nodes was patent blue dye injected into the peritu- moral submucosa of the open surgical specimen immediately after its removal from the abdominal cavity.

Results  Ex vivo identification of sentinel lymph node with marker occurred in 13 (35.1%) patients. The sensitivity was 40% and 60% false negative. The detailed histological examina- tion of sentinel lymph nodes with multilevel section and immunohistochemistry showed metastasis in one (4.3%) individual, considered ultra-staging.

Conclusion The ex vivo identification of sentinel lymph node had questionable benefits, and worse results when include patients with rectal cancer. Restaging of one patient was possible after multilevel section and immunohistochemistry of the sentinel lymph node, but more research is needed to evaluate the role of micrometastases in patients with colorectal cancer.

In vivo sentinel lymph node identification using fluorescent tracer imaging in colon cancer: A systematic review and meta-analysis

INTRODUCTION

The use of fluorescence might improve the performance of the sentinel lymph node procedure in patients with colon cancer. This systematic review was conducted to gain insight in the performance and applicability of the sentinel lymph node procedure using fluorescence.

METHOD

A systematic literature search was performed. Databases were searched for prospective studies concerning sentinel node identification using fluorescence in colon cancer. Detection rate, accuracy rate and sensitivity of the sentinel lymph node procedure were calculated for early stage (T1-T2) and more invasive (T3-T4) tumours.

RESULTS

Analyses of five included studies showed for respectively T3-T4 and T1-T2 tumours a detection rate of 90 % and 91 %, an accuracy rate of 77 % and 98 %, and a sensitivity of 30 % and 80 %.

CONCLUSION

The sentinel lymph node procedure using fluorescence in early stage (T1-T2) colon cancer seems to be promising. Larger cohorts are necessary to confirm these results.

Predictive value of the sentinel lymph node procedure in the staging of non-metastatic colorectal cancer

PURPOSE

Despite the recent growing interest of the scientific community, there is still no consensus on the actual applicability and effectiveness of sentinel lymph node (SL) procedure in colon cancers. This study aims to quantify feasibility, detection rate, negative predictive value, and accuracy of the SL identified with fluorescent dye in early colon cancers (ECC).

METHODS

This study conducted a consecutive sampling of 95 patients with non-metastatic colorectal cancer who have been treated with laparoscopic colon resection and complete mesocolic excision after a 25-mg indocyanine green peritumoral laparoscopic injection and SL identification with a near-infrared camera. The SL was later isolated and sent to ultra-staging.

RESULTS

Ninety-five patients with an average age of 71 (range 37-90) and a mean BMI of 25 (range 18-39) have been recruited. On the patient sample (92 Pts), an average of 1.49 SL (range 1-5) and a mean time of 4 min were identified. The detection rate was 96.8% and the negative predictive value and accuracy rates were 96.2% and 93.4%, respectively.

CONCLUSIONS

Mapping the SL with fluorescent dye can play an important role in the treatment of colon cancers, particularly those at early stages, and can lead to ultra-conservative surgery.

Sentinel Lymph Node Biopsy in Colon Cancer: an Institutional Experience

Lymph node staging is a major prognostic factor in colorectal cancer and remains to be the most important criterion for selecting patients for adjuvant therapy. The standard approach for lymph node evaluation is based on manual dissection and histological evaluation of HE-stained slides. For stage III disease (node positive), adjuvant chemotherapy increases the survival rate, while in node-negative stage II disease, in most cases, the chemotherapy is contraindicated due to increased morbidity without real benefit. Up to 30% of patients with node-negative colon cancer staged by standard pathologic techniques ultimately suffer disease recurrence and tumour-related mortality following potentially curative primary resection. Variations in outcome among patients with node-negative early-stage disease may reflect inadequate nodal resection and inaccuracies of pathologic staging. Hence, an accurate pN stage becomes essential. It is seen that classic pathological exam sometimes fails to identify lymph node micrometastases or isolated tumour cells, which might explain local or distant relapses in stage II patients. Sentinel lymph node study has the potential to detect micrometastases and lead to upstaging the disease which is crucial for planning adjuvant therapy and follow-up in these patients. In our study, we carried out SLNB in 40 clinically stage II patients operated for colon cancer. We used peritumoural injection of dye at the time of surgery to detect SLN(s) and analysed them using both microsectioning and immunohistochemical (IHC) staining. Our results show that SLNB can improve the accuracy of pTNM staging.

Sentinel lymph node mapping procedure in T1 colorectal cancer: A systematic review of published studies

OBJECTIVE

to investigate the role of sentinel lymph node mapping procedure in T1 Colorectal cancer.

BACKGROUND

The incidence of T1 Colorectal cancer is increasing thanks to screening and awareness campaigns. The issue concerning T1 is when to consider a local treatment curative or when it is necessary a radical resection. The histopathological features of resected polyps are able to predict the nodal spread but the value of specificity is increasingly a problem of these predictors. The sentinel lymph node procedure could be a solution.

METHODS

A systematic review was performed following PRISMA guidelines and using "sentinel node", "lymph nodes", and "colorectal cancer" as search terms in PubMed and Embase databases. References from included studies, review articles, and editorials were cross-checked. The risk of bias and quality of the included studies were assessed using the QUADAS-2 tool. The primary outcome was sentinel lymph node accuracy rate and the secondary outcome was sentinel lymph node detection rate for T1 Colorectal cancer.

RESULTS

A total of 12 studies (108 patients) met inclusion and exclusion criteria, 8 were monocentric cohort studies and 4 were multicentric cohort studies. The rate of sentinel lymph node accuracy in T1 colorectal cancer varies from 89% to 100%. Only 1 false negative was found. In 7 of these 12 studies (71 patients) the detection rate of T1 colorectal cancer was reported and showed a variation from 92% to 100%. Even in this case, only 1 case of failed procedure was found.

DISCUSSION

The literature on this topic agrees on that sentinel lymph node mapping, differently from breast cancer and melanomas should not be used for therapeutic purposes in colorectal cancer, but mainly to refine staging. The reason is the low sensitivity of this procedure with an accompanying high false negative rate. However, the data refers mainly to advanced stages of the disease because there are few data available on the earlier stages and in particular related to T1. Isolating the data related only to T1, the false negative rate seems to be very low. Additional studies are necessary, but a decisional role of sentinel lymph node mapping on the treatment of T1 Colorectal cancer is possible in the future.

Intraoperative Sentinel Node Mapping in the Colon: Potential and Pitfalls

Sentinel lymph node mapping (SLNM) may play a significant role in future delivery of colon cancer surgery because of an increase in early-stage, node-negative disease due to national bowel cancer screening programmes. Traditionally, colon lymphatic drainage has not been thought relevant as the operative approach cannot be tailored. Recent advances in local and endoscopic risk-reducing interventions for colonic malignancy have caused a rethink in approach. SLNM was initially attempted with blue dye techniques with limited success. Technological improvement has allowed surgeons to use near-infrared (NIR) light and NIR active tracers such as indocyanine green. This review provides an overview of the current status of intraoperative lymph node mapping in the colon, identifies challenges to the delivery of the techniques, and discusses potential solutions that may help SLNM play a role in improving the delivery of surgical care for patients with colon cancer.

A pilot study to assess near infrared laparoscopy with indocyanine green (ICG) for intraoperative sentinel lymph node mapping in early colon cancer

BACKGROUND

Previous attempts at sentinel lymph node (SLN) mapping in colon cancer have been compromised by ineffective tracers and the inclusion of advanced disease. This study evaluated the feasibility of fluorescence detection of SLNs with indocyanine green (ICG) for lymphatic mapping in T1/T2 clinically staged colonic malignancy.

METHODS

Consecutive patients with clinical T1/T2 stage colon cancer underwent endoscopic peritumoral submucosal injection of indocyanine green (ICG) for fluorescence detection of SLN using a near-infrared (NIR) camera. All patients underwent laparoscopic complete mesocolic excision surgery. Detection rate and sensitivity of the NIR-ICG technique were the study endpoints.

RESULTS

Thirty patients mean age = 68 years [range = 38-80], mean BMI = 26.2 (IQR = 24.7-28.6) were studied. Mesocolic sentinel nodes (median = 3/patient) were detected by fluorescence within the standard resection field in 27/30 patients. Overall, ten patients had lymph node metastases, with one of these patients having a failed SLN procedure. Of the 27 patients with completed SLN mapping, nine patients had histologically positive lymph nodes containing malignancy. 3/9 had positive SLNs with 6 false negatives. In five of these false negative patients, tumours were larger than 35 mm with four also being T3/T4.

CONCLUSION

ICG mapping with NIR fluorescence allowed mesenteric detection of SLNs in clinical T1/T2 stage colonic cancer. CLINICALTRIALS.GOV: ID: NCT01662752.

Evaluation of lymph flow patterns in splenic flexural colon cancers using laparoscopic real-time indocyanine green fluorescence imaging

PURPOSE

The treatment of splenic flexural colon cancer is not standardized because the lymphatic drainage is variable. The aim of this study is to evaluate the lymph flow at the splenic flexure.

METHODS

From July 2013 to January 2016, consecutive patients of the splenic flexural colon cancer with a preoperative diagnosis of N0 who underwent laparoscopic surgery were enrolled. Primary outcome is frequency of the direction of lymph flow from splenic flexure. We injected indocyanine green (2.5 mg) into the submucosal layer around the tumor and observed lymph flow using the laparoscopic near-infrared camera system in 30 min after injection.

RESULTS

Thirty-one patients were enrolled in this study. The lymph flow was visualized in 31 patients (100 %) without any complications. No case exhibited lymph flow in both the left colic artery (LCA) and left branch of the middle colic artery (lt-MCA) areas. There were 19 cases (61.3 %) with lymph flow directed to the area of the root of the inferior mesenteric vein (IMV), regardless of the presence of the left accessory aberrant colic artery. Lymph node metastases were observed in six cases (19.4 %), and all of the involved lymph nodes existed in lymph flow areas determined by real-time indocyanine green fluorescence imaging.

CONCLUSIONS

The findings of the lymph flow pattern of splenic flexure suggest that lymph node dissection at the root of the IMV area is important, and it may be not necessary to ligate both the lt-MCA and LCA, at least in cases without widespread lymph node metastases.

Immunohistochemical Study of Sentinel Lymph Node in Colon Cancer

Identification of sentinel lymph node (SLN) in colon cancer is very important in order to increase the accuracy of lymph node staging. The number of examined lymph nodes represents a significant predictor of survival. This study aims to show the importance of SLN histological and immunohistochemical examination in adjuvant oncological treatment. The study includes 23 patients with colon cancer (44% women and 56% men) who came in our clinic for surgical intervention. In all cases, the SLN was identified and prepared for histological examination. In 13 of the cases, micrometastases were found onhaematoxylin-eosin (HE) staining, there were 5 cases with positive immunohistochemistry using antibodies anti-p53, anti-VEGF-C, anti-CD34, and 5 cases with SLN negative both for HE and immunohistochemistry. Altogether we had a detection rate of 92%, an accuracy of 78,2%, a sensitivity of 90%, a false negative rate of 10% and a negative predictive value of 71,4%, good values according to the literature. Four (17,3%) patients had micrometastases exclusively in the sentinel lymph node, after performing additional histological examination, using multilevel section and immunohistochemistry. After assessing the SNL on our patients, we concluded that it is a reproducible practice for lymph node analysis.

Intra-operative tumour detection and staging in colorectal cancer surgery

AIM

Surgical resection for colorectal cancer involves segmental resection and regional lymphadenectomy. The appropriateness of this 'one-size-fits-all' strategy is questioned as bowel cancer screening programmes result in a shift to earlier stage disease. Currently, the nodal status of a colorectal cancer can only be reliably determined by histopathological examination of the resected specimen. New methods of intra-operative staging are required to allow surgical resection to be tailored to the stage of the disease.

METHOD

A literature search was performed of PubMed and Embase databases using the terms 'colon' OR 'colorectal' AND 'intra-operative detection' OR 'intra-operative staging' OR 'intra-operative detection' OR 'radioimmunoguided surgery'. Articles published between January 1980 and January 2012 were included. Technologies that have the potential to allow intra-operative staging and treatment stratification were identified and further searches performed.

RESULTS

Established techniques such as sentinel lymph node mapping and radioimmunoguided surgery have benefited from combination with other technologies to allow real-time intra-operative staging. Intra-operative fluorescence, using naturally fluorescent biomarkers or fluorescent tumour probes, probably offers the most practical means of intra-operative lymph node staging and may be facilitated using nanotechnology. Optical coherence tomography and real-time elastography have the potential to provide an in vivo'virtual biopsy'.

CONCLUSION

Technological advances may allow accurate intra-operative lymph node staging to facilitate tailored surgical resection. This may become the next paradigm shift in colorectal cancer surgery.

Ex vivo localization and immunohistochemical detection of sentinel lymph node micrometastasis in patients with colorectal cancer can upgrade tumor staging

BACKGROUND

It is not clear if sentinel lymph node (SLN) mapping can improve outcomes in patients with colorectal cancers. The purpose of this study was to determine the prognostic values of ex vivo sentinel lymph node (SLN) mapping and immunohistochemical (IHC) detection of SLN micrometastasis in colorectal cancers.

METHODS

Colorectal cancer specimens were obtained during radical resections and the SLN was identified by injecting a 1% isosulfan blue solution submucosally and circumferentially around the tumor within 30 min after surgery. The first node to stain blue was defined as the SLN. SLNs negative by hematoxylin and eosin (HE) staining were further examined for micrometastasis using cytokeratin IHC.

RESULTS

A total of 54 patients between 25 and 82 years of age were enrolled, including 32 males and 22 females. More than 70% of patients were T3 or above, about 86% of patients were stage II or III, and approximately 90% of patients had lesions grade II or above. Sentinel lymph nodes were detected in all 54 patients. There were 32 patients in whom no lymph node micrometastasis were detected by HE staining and 22 patients with positive lymph nodes micrometastasis detected by HE staining in non-SLNs. In contrast only 7 SLNs stained positive with HE. Using HE examination as the standard, the sensitivity, non-detection rate, and accuracy rate of SLN micrometastasis detection were 31.8% (7/22), 68.2% (15/22), and 72.2%, respectively. Micrometastasis were identified by ICH in 4 of the 32 patients with HE-negative stained lymph nodes, resulting in an upstaging rate 12.5% (4/32). The 4 patients who were upstaged consisted of 2 stage I patients and 2 stage II patients who were upstaged to stage III. Those without lymph node metastasis by HE staining who were upstaged by IHC detection of micrometastasis had a significantly poorer disease-free survival (p = 0.001) and overall survival (p = 0.004).

CONCLUSION

Ex vivo localization and immunohistochemical detection of sentinel lymph node micrometastasis in patients with colorectal cancer can upgrade tumor staging, and may become a factor affecting prognosis and guiding treatment.

Implications of sentinel lymph node mapping on nodal staging and prognosis in colorectal cancer

AIM

Sentinel lymph node (SN) mapping for staging in colorectal cancer remains controversial and needs to be validated before it can be implemented in daily practice. We prospectively assessed the effect of SN mapping on nodal staging and its implication on survival in patients with colorectal cancer.

METHOD

Between November 2005 and July 2009, 331 patients underwent a resection for colorectal cancer. In 189 patients (group A) an ex-vivo SN procedure was performed with immunohistochemical analysis of the SN. Tumour cell deposits between 0.2 mm and 2.0 mm were referred to as micrometastases (pN1mi+). The remaining patients (n = 142, group B) had standard nodal staging. Multivariate Cox regression analysis was performed to identify prognostic factors for disease recurrence.

RESULTS

The average number of harvested lymph nodes was higher in group A than in group B (15.5 ± 7.3 vs 12.1 ± 5.2, P < 0.0001). After conventional staging, 81 (43%) patients of group A were judged to have nodal metastasis. This increased to 89 (47%) patients when immunohistochemically detected micrometastases were included. In group B, 50 (35%) patients had nodal metastasis. During follow up, a lower recurrence rate was seen in N0 patients after SN mapping compared with the conventional staging group (4%vs 15.2%, P = 0.04). The SN procedure (hazard ratio = 4.1) was an independent predictor of disease recurrence.

CONCLUSION

The SN procedure results in a more accurate staging of patients with colorectal cancer. This is reflected by a better prognosis of N0 patients after SN mapping.

Analysis of sentinel lymph node biopsy results in colon cancer in regard of the anthropometric features of the population and body composition assessment formulas

Purpose

The aim of the study was to assess sentinel lymph node biopsy (SLNB) results in colon cancer (CC) regarding basic anthropometric features of the studied population and their derivatives calculated using mathematical formulas.

Methods

One hundred three SLNBs in CC have been analysed. Various indicators were calculated for every patient using mathematical formulas: BMI, Roher’s index, lean body weight, body fat percentage and body weight/ideal body weight for a given height ratios using the following formulas: Broca’s, Broca’s ideal weight, Broca–Brugsch, Lorenz’s, Potton’s, Devine’s, Robinson’s, Miller’s and Hamwi. The results were compared with accuracy, sensitivity and false negative results percentage by means of ROC curves and the test for structure indicators (for determined cut-off points).

Results

No statistically significant relationship between the results and patients' sex or age were found. ROC curve analysis did not reveal statistically significant relationships between the obtained results and indicators calculated on the basis of growth and weigh (all p > 0.05). The analyses of sensitivity and accuracy with determined cut-off point, in spite of differences amounting to 19 % (analysis of lean body weight/weight ratio), showed no statistical significance for any of the relationships (all p > 0.05).

Conclusions

No indicator with high diagnostic and prognostic value has been found. The problem of qualifying patients for SLNB in CC in regard of the anthropometric features of the population and body composition assessment formulas remains open and requires further analysis on larger populations.

Ultrastaging of colon cancer by sentinel node biopsy using fluorescence navigation with indocyanine green

PURPOSE

Lymph node status is the most important prognostic factor in colon cancer, but the role of sentinel lymph node biopsy (SLNB) as a tool for identification of micrometastatic disease and extraanatomical lymph nodes for adjuvant strategies and a tailored approach still remains unclear. Indocyanine green (ICG) fluorescence detection is a new method for SLNB allowing real-time lymphography and lymph node detection. This study was designed to evaluate the feasibility of fluorescence-guided sentinel lymph node detection in colon carcinoma.

METHODS

Twenty six patients with colon adenocarcinoma were prospectively included in this study. Intraoperatively, a peritumorous injection with a mean of 2.0 ml ICG was performed, followed by lymphatic mapping and SLNB. Clinical feasibility, detection rate, and sensitivity of the method were analyzed.

RESULTS

No adverse reactions occurred due to the injection of ICG. Overall, ICG fluorescence imaging identified 1.7 sentinel lymph node (SLN) in average in 25 out of 26 patients (detection rate, 96%). Metastatic involvement of the SLN was found in nine out of 11 nodal positive patients by conventional histopathology. The sensitivity of the method was 82% for colon carcinoma, respectively.

CONCLUSION

ICG fluorescence imaging is a new, feasible method for SLNB of colon carcinoma and enables ultrastaging with improved accuracy but with limited validity due to the small number of cases. One advantage of this technique is real-time visualization of lymphatic vessels and SLNB without radiation exposure. Further, larger series are necessary to analyze the role of fluorescence-guided SLNB for colon cancer.

Near infrared fluorescence lymphatic laparoscopy of the colon and mesocolon

During surgery, a surgeon relies on the vision of his eyes and the touch of his hands. While laparoscopic surgery for colon cancer has proven to be safe and effective, it still remains a technically difficult procedure. Although it is associated with reduced haptic feedback, by enforcing the power of visual guidance, the loss of this feedback can be (partly) compensated for. Here we describe how the use of near-infrared dyes and fluorescence laparoscopy could help improve tumour staging and therefore lead to better selection of patients for postoperative adjuvant chemotherapy. More controversially, and analogous to melanoma and breast cancer surgery with sentinel node biopsy, we speculate that local resection with SLN harvesting in early colon cancer might change the therapeutic and surgical strategy in colon cancer.

Sentinel-lymph-node procedure in colon and rectal cancer: a systematic review and meta-analysis

BACKGROUND

No consensus exists on the validity of the sentinel-lymph-node procedure for assessment of nodal status in patients with colorectal cancer. We aimed to assess the diagnostic performance of this procedure.

METHODS

We searched Embase and PubMed databases for studies published before March 20, 2010. Eligible studies had a prospective design, a sample size of at least 20 patients, and reported the rate of sentinel-lymph-node positivity. Individual patient data were requested for localisation and T-stage stratification. A subset of reports with high methodological quality was selected and analysed.

FINDINGS

We identified 52 eligible studies, which included 3767 sentinel-lymph-node procedures (2961 [78·6%] colon and 806 [21·4%] rectal carcinomas). Most tumours 2339 (62·1%) were stage T3 or T4. 1887 (50·1%) of patients were male, 1880 (49·9%) female. Mean overall weighted-detection rate was 0·94 (95% CI 0·92-0·95), at a pooled sensitivity of 0·76 (0·72-0·80) with limited heterogeneity (χ(2)=286·08, degrees of freedom=51; p=0·003). A mean weighted upstaging of 0·15 (95% CI 0·12-0·19) was noted. Individual patient data were available from 19 studies that included 1168 patients. Analysis of these data showed no significant difference in sensitivity between colon (0·86 [95% CI 0·83-0·90]) and rectal cancer (0·82 [0·77-0·88]; p=0·23). Also, there was no dependency of sensitivity on T stage for both colon (pT1: 0·79 [95% CI 0·73-0·84], pT2: 0·76 [0·62-0·90], pT3: 0·73 [0·59-0·87], pT4: 0·73 [0·53-0·93]) and rectal cancer (T1 or T2: 0·81 [0·52-0·94] vs T3 or T4: 0·80 [0·51-0·93]). The subgroup of eight studies with high methodological quality showed a mean detection rate of 0·96 (95% CI 0·90-0·99) for colonic tumours and 0·95 (0·75-0·99) for rectal tumours, and a mean sensitivity of 0·90 (95% CI 0·86-0·93) for colonic tumours and 0·82 (0·60-0·93) for rectal tumours.

INTERPRETATION

The sentinel-lymph-node procedure shows a low sensitivity, regardless of T stage, localisation, or pathological technique. For every patient diagnosed with colon or rectal cancer without clinical evidence of lymph-node involvement or metastatic disease, this procedure in addition to conventional resection should be considered, since the prognostic information provided by this technique could be clinically significant.

FUNDING

Cancer Center Amsterdam Foundation, Amsterdam, Netherlands.

Sentinel node procedure of the sigmoid using indocyanine green: feasibility study in a goat model

BACKGROUND

The sentinel lymph node (SLN) procedure alter the strategy for the treatment of patients with colon cancer. New techniques emerge that may provide the surgeon with a tool for accurate intraoperative detection of the SLNs.

METHODS

An SLN procedure of the sigmoid was used in six goats. During laparoscopy, the near-infrared dye indocyanine green (ICG) was injected into the subserosa of the sigmoid via a percutaneously inserted needle during four experiments and in the submucosa during colonoscopy in two experiments. After injection, the near-infrared features of a newly developed laparoscope were used to detect the lymph vessels and SLNs. At the end of the procedure, 2 h after injection, all the goats were killed, and autopsy was performed. During postmortem laparotomy, the sigmoid was removed and used for confirmation of ICG node uptake.

RESULTS

In all the procedures, the lymph vessels were easily detected by their bright fluorescent emission. In the first two experiments, no lymph nodes were detected. In the subsequent four experiments, human serum albumin was added to the ICG solution before injection to enable better lymph node entrapment. In all four experiments, at least one bright fluorescent lymph node was found after the lymph vessels had been tracked by their fluorescent guidance. The mean time between injection and SLN identification was 10 min. In two cases, the SLNs were located up to 5 mm into the fat tissue of the mesentery and were not seen by regular vision of the laparoscope. By switching on the near-infrared features of the scope, a clear bright dot became visible, which increased in intensity after opening of the mesentery.

CONCLUSION

The SLN procedure for the sigmoid using near-infrared laparoscopy in the goat is a very promising technique. Achievements described in this report justify a clinical trial on the feasibility of ICG-guided SLN detection in humans.

Quantitative RT-PCR detection of tumor cells in sentinel lymph nodes isolated from colon cancer patients with an ex vivo approach

OBJECTIVE

To investigate quantitative RT-PCR-based detection of tumor cells in lymph nodes (LNs) isolated from colon cancer patients by ex vivo sentinel lymph node (SLN) mapping.

SUMMARY BACKGROUND DATA

Although lymph node status is among the strongest prognostic factors in colon cancer patients, 20% to 30% of node negative patients experience disease recurrence. These patients may have LN metastases that are not detected by routine examination.

METHODS

Ex vivo SLN mapping was applied to 131 prospectively recruited patients undergoing curative surgery for primary colon cancer. The SLNs were analyzed for the presence of tumor cells by routine histology and real-time RT-PCR quantitation of cytokeratin 20 (CK20) and mucin 2(MUC2) mRNA.

RESULTS

SLNs were identified in 125 (95%) of the 131 patients included.Routine histologic analysis of SLNs and other regional lymph nodes revealed LN metastases in 42 patients (N+), of which 29 (69%) had metastases detected in 1 or more SLNs (sensitivity, 69%; false negative rate, 31%).When analyzing the SLNs by quantitative RT-PCR, the sensitivity, compared with routine LN examination, was 37/42 (88%) for both the CK20 and the MUC2 mRNA markers. In addition, 46% and 27% of the patients' node negative by routine LN examination (N0) were positive for the CK20 and MUC2 mRNA markers, respectively, possibly reflecting the presence of occult tumor cells in their SLNs.

CONCLUSIONS

Quantitative RT-PCR analysis of SLNs identified N+ patients with high sensitivity and revealed a subgroup of N0 patients with potential occult LN disease.

Supplementation of endoscopic submucosal dissection with sentinel node biopsy performed by natural orifice transluminal endoscopic surgery (NOTES) (with video)

BACKGROUND

Endoscopic submucosal dissection (ESD) is proving to be effective for the resection of selected early gastric and colon cancers. Its application and appropriateness could be extended if a means of determining lymphatic dissemination without recourse to a conventional operation could be provided.

OBJECTIVE

To demonstrate the feasibility of companion sentinel node biopsy (SNB) by natural orifice transluminal endoscopic surgery (NOTES) concurrent with intraluminal ESD in both the sigmoid colon and stomach.

DESIGN

Acute porcine model.

INTERVENTION

Arbitrarily selected mucosal foci were targeted for combined NOTES-SNB and ESD in the sigmoid and stomach of 2 separate anesthetized animals. NOTES peritoneal access was obtained either transgastrically or transvaginally. A second intraluminal endoscope was passed either orally or rectally, as appropriate, to perform submucosal injection for lymphatic mapping under direct vision of the NOTES endoscope. This endoscope then identified the first-order draining (sentinel) nodes and allowed their excisional biopsy. The sigmoid was retracted by magnetic assistance as required, while torque of an intraluminal gastroscope manipulated the stomach. After retrieval of the nodes, 1-cm and 1.5-cm specimens were resected from the sigmoid and stomach, respectively, by conventional ESD. At procedure end, necropsy was performed.

RESULTS

All sentinel nodes were identified, underwent biopsy, and were retrieved intact. ESD was subsequently readily performed without complication. SNB completeness and ESD quality were confirmed postprocedure.

LIMITATIONS

Experimental model with limited sample size.

CONCLUSIONS

Although not yet appropriate for human use, this proposal merits serious consideration as a potential means of augmenting the effectiveness and appropriateness of ESD techniques for GI neoplasia.

The potential of cytokeratin 20 and mucin 2 mRNA as metastasis markers in regional lymph nodes of colon cancer patients investigated by quantitative RT-PCR

PURPOSE

The presence of regional lymph node metastases is one of the most important prognostic factors in colon cancer. Nevertheless, up to 30% of the lymph node negative patients experience disease recurrence. Possibly, this patient group may be identified by more sensitive techniques than routine histopathological examination of the lymph nodes.

METHODS

In the present study, we have evaluated the detection of colon cancer lymph node metastases by real-time RT-PCR quantitation of the epithelial-specific cytokeratin 20 (CK20) and mucin 2 (MUC2) mRNAs.

RESULTS

Both assays were able to detect dilutions of tumor cells down to one tumor cell in 10(6) normal lymphocytes. CK20 and MUC2 mRNA were quantitated in 52 normal lymph nodes from 12 patients undergoing surgery for benign bowel diseases and in 144 primary colon tumors. The median tumor level of both markers were more than 10(4)-fold higher than the highest level in normal lymph nodes, indicating that the markers had a potential for metastasis detection in a clinical context. We applied the assays to 61 lymph nodes with known metastases detected by routine staining. Elevated CK20 or MUC2 mRNA levels were detected in 57 (95%) of the 61 LNs.

CONCLUSIONS

Thus, CK20 and MUC2 quantitation by real-time RT-PCR seems to be a promising, sensitive tool to detect metastases in regional lymph nodes from colon cancer patients.

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.