Comparison of ex vivo and in vivo injection of blue dye in sentinel lymph node mapping for colorectal cancer

Lymphatic Mapping in Colon Cancer Depending on Injection Time and Tracing Agent: A Systematic Review and Meta-Analysis of Prospective Designed Studies

An optimized lymph node yield leads to better survival in colon cancer, but extended lymphadenectomy is not associated with survival benefits. Lymphatic mapping shows several colon cancers feature aberrant drainage pathways inducing local recurrence when not resected. Currently, different protocols exist for lymphatic mapping procedures. This meta-analysis assessed which protocol has the best capacity to detect tumor-draining and possibly metastatic lymph nodes. A systematic review was conducted according to PRISMA guidelines, including prospective trials with in vivo tracer application. The risk of bias was evaluated using the QUADAS-2 tool. Traced lymph nodes, total resected lymph nodes, and aberrant drainage detection rate were analyzed. Fifty-eight studies met the inclusion criteria, of which 42 searched for aberrant drainage. While a preoperative tracer injection significantly increased the traced lymph node rates compared to intraoperative tracing (30.1% (15.4, 47.3) vs. 14.1% (11.9, 16.5), p = 0.03), no effect was shown for the tracer used (p = 0.740) or the application sites comparing submucosal and subserosal injection (22.9% (14.1, 33.1) vs. 14.3% (12.1, 16.8), p = 0.07). Preoperative tracer injection resulted in a significantly higher rate of detected aberrant lymph nodes compared to intraoperative injection (26.3% [95% CI 11.5, 44.0] vs. 2.5% [95% CI 0.8, 4.7], p < 0.001). Analyzing 112 individual patient datasets from eight studies revealed a significant impact on aberrant drainage detection for injection timing, favoring preoperative over intraoperative injection (OR 0.050 [95% CI 0.010-0.176], p < 0.001) while indocyanine green presented itself as the superior tracer (OR 0.127 [95% CI 0.018-0.528], p = 0.012). Optimized lymphatic mapping techniques result in significantly higher detection of aberrant lymphatic drainage patterns and thus enable a personalized approach to reducing local recurrence.

Role of methylene blue in detecting the sentinel lymph node in colorectal cancer: In vivo vs. ex vivo technique

The identification of sentinel lymph nodes is a valuable oncological method, which aims at mapping lymphatic drainage and has the advantage of correctly staging the disease and assessing prognosis. Lymph node invasion is an important prognostic feature. In colorectal cancer, lymphadenectomy is not influenced by the positive or negative status of the sentinel lymph node. The identification of lymph nodes with possible invasion by staining the primary tumor with methylene blue can lead to improved staging and management. In other words, the consequent administration of neoadjuvant therapy (chemotherapy) to the appropriate patients may result in lower recurrence rates. Thus, the aim of the present study was to use methylene blue to identify the sentinel node/nodes in colorectal cancer and to determine whether the dye-capturing nodes were invaded by the tumor. This is a non-randomized prospective study, in which 26 patients with colon cancer with surgical indication were enrolled. Two types of methods were utilized: in vivo (16 patients) and ex vivo (10 patients). The identification rate was 75% for the in vivo technique and 60% for the ex vivo technique, resulting in a 69.26% overall identification rate. Of 18 patients with sentinel lymph nodes identified using dye, routine histological examination detected metastases in 6 (33.33%) of these patients. In conclusion, further research should be conducted into how the clinical application of sentinel node detection can be employed in colorectal cancer.

Upstaging nodal status in colorectal cancer using ex vivo fluorescence sentinel lymph node mapping: preliminary results

BACKGROUND

Sentinel lymph node (SLN) mapping using near-infrared fluorescence (NIRF) imaging is a recent technique to improve nodal staging in several tumors. The presence of colorectal cancer (CRC) micro-metastases has recently been defined as N1 disease and no longer as N1mi, determining the need for adjuvant chemotherapy. In CRC, the reported rate of SLN micro-metastases detected by ultrastaging techniques is as high as 30%. The aim of this prospective study is to report the preliminary results of the sensitivity analysis of NIRF imaging for ex vivo SLN mapping and the research of micro-metastases in CRC, in patients with node-negative disease (NND).

MATERIAL AND METHODS

On the specimen of 22 CRC patients, 1 mL of ICG (5 mg/mL) was injected submucosally around the tumor to identify SLNs. NND SLNs were further investigated with ultrastaging techniques.

RESULTS

Three-hundred and sixty-three lymph nodes were retrieved (59 SLNs; mean per case: 2.7). The detection, sensitivity and false-negative rate were 100%, 100% and 0% respectively. Ultrastaging investigations showed no micro-metastases in the NND SLNs.

CONCLUSIONS

The ex vivo SLN fluorescence-based detection in CRC was confirmed to be easy to perform and reliable. In this preliminary results report of an ongoing study, the SLN assay was congruent with the nodal status, as confirmed by histological investigations.

Near-infrared fluorescence imaging for sentinel lymph node identification in colon cancer: a prospective single-center study and systematic review with meta-analysis

Background

Near-infrared (NIR) fluorescence imaging has the potential to overcome the current drawbacks of sentinel lymph node mapping (SLNM) in colon cancer. Our aim was to provide an overview of current SLNM performance and of factors influencing successful sentinel lymph node (SLN) identification using NIR fluorescence imaging in colon cancer.

Methods

A systematic review and meta-analysis was conducted to identify currently used methods and results. Additionally, we performed a single-center study using indocyanine green (ICG) as SLNM dye in colon cancer patients scheduled for a laparoscopic colectomy. SLNs were analyzed with conventional hematoxylin-and-eosin staining and additionally with serial sectioning and immunohistochemistry (extended histopathological assessment). A true-positive procedure was defined as a tumor-positive SLN either by conventional hematoxylin-and-eosin staining or by extended histopathological assessment, independently of regional lymph node status. SLN procedures were determined to be true negatives if SLNs and regional lymph nodes revealed no metastases after conventional and advanced histopathology. SLN procedures yielding tumor-negative SLNs in combination with tumor-positive regional lymph nodes were classified as false negatives. Sensitivity, negative predictive value and detection rate were calculated.

Results

This systematic review and meta-analysis included 8 studies describing 227 SLN procedures. A pooled sensitivity of 0.63 (95% CI 0.51–0.74), negative predictive value 0.81 (95% CI 0.73–0.86) and detection rate of 0.94 (95% CI 0.85–0.97) were found. Upstaging as a result of extended histopathological assessment was 0.15 (95% CI 0.07–0.25). In our single-center study, we included 30 patients. Five false-negative SLNs were identified, resulting in a sensitivity of 44% and negative predictive value of 80%, with a detection rate of 89.7%. Eight patients had lymph node metastases, in three cases detected after extended pathological assessment, resulting in an upstaging of 13% (3 of 23 patients with negative nodes by conventional hematoxylin and eosin staining).

Conclusions

Several anatomical and technical difficulties make SLNM with NIR fluorescence imaging in colon cancer particularly challenging when compared to other types of cancer. As a consequence, reports of SLNM accuracy vary widely. Future studies should try to standardize the SLNM procedure and focus on early-stage colon tumors, validation of tracer composition, injection mode and improvement of real-time optical guidance.

Electronic supplementary material

The online version of this article (10.1007/s10151-019-02107-6) contains supplementary material, which is available to authorized users.

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.

In vivo and ex vivo sentinel node mapping does not identify the same lymph nodes in colon cancer

INTRODUCTION

Identification of lymph nodes and pathological analysis is crucial for the correct staging of colon cancer. Lymph nodes that drain directly from the tumor area are called "sentinel nodes" and are believed to be the first place for metastasis. The purpose of this study was to perform sentinel node mapping in vivo with indocyanine green and ex vivo with methylene blue in order to evaluate if the sentinel lymph nodes can be identified by both techniques.

METHODS

Patients with colon cancer UICC stage I-III were included from two institutions in Denmark from February 2015 to January 2016. In vivo sentinel node mapping with indocyanine green during laparoscopy and ex vivo sentinel node mapping with methylene blue were performed in all patients.

RESULTS

Twenty-nine patients were included. The in vivo sentinel node mapping was successful in 19 cases, and ex vivo sentinel node mapping was successful in 13 cases. In seven cases, no sentinel nodes were identified. A total of 51 sentinel nodes were identified, only one of these where identified by both techniques (2.0%). In vivo sentinel node mapping identified 32 sentinel nodes, while 20 sentinel nodes were identified by ex vivo sentinel node mapping. Lymph node metastases were found in 10 patients, and only two had metastases in a sentinel node.

CONCLUSION

Placing a deposit in relation to the tumor by indocyanine green in vivo or of methylene blue ex vivo could only identify sentinel lymph nodes in a small group of patients.

Combination of Fluorescence-Guided Surgery With Photodynamic Therapy for the Treatment of Cancer

Specific visualization of body parts is needed during surgery. Fluorescence-guided surgery (FGS) uses a fluorescence contrast agent for in vivo tumor imaging to detect and identify both malignant and normal tissues. There are several advantages and clinical benefits of FGS over other conventional medical imaging modalities, such as its safety, effectiveness, and suitability for real-time imaging in the operating room. Recent advancements in contrast agents and intraoperative fluorescence imaging devices have led to a greater potential for intraoperative fluorescence imaging in clinical applications. Photodynamic therapy (PDT) is an alternative modality to treat tumors, which uses a light-sensitive drug (photosensitizers) and special light to destroy the targeted tissues. In this review, we discuss the fluorescent contrast agents, some newly developed imaging devices, and the successful clinical application of FGS. Additionally, we present the combined strategy of FGS with PDT to further improve the therapeutic effect for patients with cancer. Taken together, this review provides a unique perspective and summarization of FGS.

Techniques to increase lymph node harvest from gastrointestinal cancer specimens: a systematic review and meta-analysis

AIMS

This review aims to compare different histopathological techniques for lymph node harvest from ex-vivo gastrointestinal cancer specimens and to examine their influence on: (i) lymph node yield; (ii) positive lymph node detection; and (iii) cancer staging.

METHOD AND RESULTS

Systematic review of the English language literature to 10 October 2011, comparing manual nodal dissection to other techniques for lymph node harvest. The methodological quality of included studies was assessed. Twenty-seven studies, examining fat clearing, methylene blue staining, fat stretching and use of a dedicated pathology assistant, were assessed. The methodological quality of the majority of included studies was poor. Meta-analysis showed that fat clearing and methylene blue staining increased mean lymph node yield by 13 and 15 nodes, respectively, when compared to manual dissection. Of the 15 studies reporting positive lymph node count, two demonstrated a significant improvement for techniques other than manual dissection. Compared to manual dissection, other techniques were not shown to influence cancer staging.

CONCLUSION

This review has shown that fat clearing and methylene blue staining increases the mean lymph node yield from gastrointestinal cancer specimens. There is insufficient evidence to suggest that these techniques increase positive lymph node count or lead to upstaging.

Real-Time Indocyanine Green Fluorescence Imaging-Guided Complete Mesocolic Excision in Laparoscopic Flexural Colon Cancer Surgery

INTRODUCTION

Laparoscopic surgery for colon cancer located in the hepatic flexure or splenic flexure is not standardized, because lymphatic drainage at this site may vary and the precise site of lymphatic dissection is uncertain.

TECHNIQUE

Indocyanine green was injected into the submucosal layer around the tumor at 2 points with a 23-gauge localized injection before lymph node dissection and the lymph flow was observed using a near-infrared camera system 30 minutes after injection. In addition, a complete mesocolic excision with central vascular ligation guided the region where the lymph flow was fluorescently observed.

RESULTS

A total of 20 consecutive patients (hepatic flexure, 10 patients; splenic flexure, 10 patients) were enrolled in this study. All of the procedures were safely performed without any complications. The lymph flow was visualized in 19 patients (95%) intraoperatively. Modification of the operative methods was required for 5 patients (modification in the separation line of the mesocolon and vessel selection for central vascular ligation) because the area of lymph flow observed during surgery differed from that of the preoperative diagnosis.

CONCLUSION

Intraoperative real-time visualization of the lymph flow using indocyanine green fluorescence imaging during laparoscopic colon cancer surgery, especially flexural colon cancer surgery, is feasible and a helpful technique for identifying appropriate central vessels to be dissected and for determining an appropriate separation line of the mesentery.

Visualization of Lymph/Blood Flow in Laparoscopic Colorectal Cancer Surgery by ICG Fluorescence Imaging (Lap-IGFI)

PURPOSE

In laparoscopic colorectal cancer (Lap-CRC) surgery, determination of a suitable mesentery division line and the appropriate degree of lymphadenectomy by tracing the blood supply is critical. We performed visualization of the lymph and blood flow by laparoscopic indocyanine green (ICG) fluorescence imaging (Lap-IGFI).

METHODS

ICG is injected into the submucosa near the tumor via colonoscopy, and the lymph flow is observed. Intestinal blood flow is evaluated by administering ICG intravenously.

RESULTS

For lymph flow, visualization of the main lymph node basin helped to determine the surgical division line for cases in which the blood flow was not completely visualized. Lap-IGFI changed the surgical plan of the lymphadenectomy in 23.5 %. In our experience, the metastatic rate of ICG-positive nodes was 10.0 %, and the metastatic rate of ICG-negative nodes was 5.3 %. Furthermore, there were no metastatic nodes that were ICG negative more than 5 cm from the tumor. For blood flow, the blood flow distribution of the intestinal wall from the last branch of the vasa recta of the anastomotic site was clearly visualized and proved useful in choosing the extent of intestinal resection. Lap-IGFI changed the surgical plan of the extensive intestinal resection in 16.7 %.

CONCLUSIONS

Lap-IGFI can noninvasively provide detailed lymph and blood flow information and is a useful device to aid in the accurate identification of individual patients' lymph drainage. This helps dictate adequate lymphadenectomy and the extent of intestinal resection in Lap-CRC surgery.

Clinical application of sentinel lymph node mapping in colon cancer: in vivo vs. ex vivo techniques

Purpose

Clinical usefulness of sentinel lymph node (SLN) mapping in colorectal cancer remains controversial. The aim of this study is to evaluate the accuracy of the SLN mapping technique using serial sectioning, and to compare the results between ex vivo and in vivo techniques.

Methods

From February 2011 to October 2012, 34 colon cancer patients underwent SLN mapping during surgical resection. Eleven patients were analyzed with the in vivo method, and 23 patients with the ex vivo method. Patient characteristics and results of SLN mapping were evaluated.

Results

The SLN mapping was performed in 34 patients. Mean age was 67.3 years (range, 44-81 years). Primary tumors were located in the following sites: 13 in the right colon (38.2%) and 21 in the left colon (61.8%). SLN mapping was performed successfully in 88.2% of the patients. There was no significant difference in the identification rate between the two methods (90.9% vs. 87.0%, P = 1.000). Both the mapping methods showed a low sensitivity and high rate of skip metastasis.

Conclusion

This study showed that SLN evaluation using serial sectioning could not predict the nodal status with clinically acceptable accuracy despite the high detection rate.

[Sentinel lymph node biopsy technique in colon cancer. Experience in 125 cases]

INTRODUCTION

The level of lymph node involvement is the most important factor in staging colorectal cancer without metastasis. Sentinel lymph node mapping identifies the node(s) that most accurately reflect the lymph node status of patients, and intensive techniques that improve staging can be focused on these nodes. The aim of this study was to assess the efficacy of ex vivo sentinel lymph node mapping in the staging of colon cancer.

MATERIALS AND METHODS

A prospective study was conducted on 125 patients from the Alava-Txagorritxu University Hospital Health Region (Alava), who were diagnosed prior to surgery with colon cancer without distant metastasis from September 2009 to December 2011. Ex vivo sentinel lymph node mapping with methylene blue was use in these patients to study the sentinel nodes with multiple slices using immunohistochemical techniques and haematoxylin-eosin staining. A comparative study was also performed based on a control group of 170 patients staged with conventional techniques, and involving a single slice and haematoxylin-eosin staining.

RESULTS

The sentinel lymph node identification rate was 98%, with 5.6% false negatives. Upstaging occurred in 14.2% of cases compared to the group studied using conventional techniques (P=.006).

CONCLUSIONS

Ex vivo sentinel lymph node mapping with methylene blue accurately reflects the lymph node status of patients with colon cancer. This approach upstages patients classified as stages i and ii by conventional techniques to stage iii, indicating chemotherapy that may improve their prognosis.

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.

Systematic review of sentinel lymph node mapping procedure in colorectal cancer

BACKGROUND

The clinical impact of sentinel lymph node (SN) biopsy in colorectal cancer is still controversial. The aim of our study was to determine the accuracy of this procedure from published data and to identify factors that contribute to the conflicting reports.

METHODS

A systematic search of the Medline, Embase, and Cochrane databases up to July 2011 revealed 98 potentially eligible studies, of which 57 were analyzed including 3,934 patients (3,944 specimens).

RESULTS

The pooled SN identification rate was 90.7% (95% CI 88.2-93.3), with a significant higher identification rate in studies including more than 100 patients or studies using the ex vivo SN technique. The pooled sensitivity of the SN procedure was 69.6% (95% CI 64.7-74.6). Including the immunohistochemical findings increased the pooled sensitivity of SN procedure to 80.2% (95% CI 4.7-10.7). Subgroups with significantly higher sensitivity could be identified: ≥4 SNs versus <4 SNs (85.2 vs. 66.3%, p = 0.003), colon versus rectal cancer (77.6 vs. 65.7%, p = 0.04), early T1 or T2 versus advanced T3 or T4 carcinomas (93.4 vs. 58.8%, p = 0.01). Serial sectioning and immunohistochemistry resulted in a mean upstaging of 18.9% (range 0-50%). True upstaging defined as micrometastases (pN1mi+) rather than isolated tumor cells (pN0itc+) was 7.7%.

CONCLUSIONS

The SN procedure in colorectal cancer has an overall sensitivity of 70%, with increased sensitivity and refined staging in early-stage colon cancer. Because the ex vivo SN mapping is an easy technique it should be considered in addition to conventional resection in colon cancer.

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.

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.

A new concept for the role of ex vivo sentinel lymph nodes in node-negative colorectal cancer

BACKGROUND

We recently introduced ex vivo, intra-arterial methylene blue injection as a simple method to improve the lymph node (LN) harvest in gastrointestinal cancer. We now combined it with a novel ex vivo sentinel lymph node (evSLN) mapping technique.

METHODS

evSLN mapping was performed by subserosal (n = 20) or submucosal (n = 30) India ink injection. Subsequently, methylene blue was injected intra-arterially to enhance visibility of all LNs to improve the overall LN harvest. Manual LN dissection was carried out after fixing overnight. evSLNs nodes were identified by detecting carbon particles during histological examination. In primary node-negative cases, all detected LNs were step sectioned and immunohistochemically stained for pan-cytokeratin.

RESULTS

India ink injection was easy to perform. Methylene blue injection failed in 1 case. The mean lymph node harvest was 42 ± 18 LNs, and the SLN detection rate was 78%. The sensitivity for detecting metastases was 75%. The mean SLN number was 3 ± 1. LN metastases were found in 20 of 47 malignant cases (43%). Skip metastases occurred in 4 cases. Of these cases, 3 showed involvement of at least 1 entire LN. True upstaging (N0 → N1mi) was found in 1 of 23 cases (4%) within a SLN after advanced evaluation.

CONCLUSIONS

Combination of methylene blue technique and ex vivo sentinel mapping is feasible, easy to perform, and cost effective. It guarantees an optimal LN harvest and has the potential to heighten the sensitivity of metastasis detection.

Ex vivo sentinel lymph node mapping in patients undergoing proctectomy for rectal cancer

PURPOSE

Controversy exists over the utility of sentinel lymph node mapping in the treatment of rectal cancer. The purpose of this study was to evaluate the use of ex vivo sentinel lymph node mapping in the setting of proctectomy for rectal cancer, with and without multilevel sectioning and immunohistochemistry.

METHODS

A prospective phase 2 clinical study of subjects undergoing proctectomy for rectal cancer from 2003 to 2008 was conducted. Sentinel lymph node mapping was performed with ex vivo injection of isosulfan blue. Sentinel lymph nodes were examined by hematoxylin and eosin evaluation, and when the results were negative, they were examined by multilevel sectioning and immunohistochemistry.

RESULTS

The study population consisted of 58 subjects; 88% received neoadjuvant therapy. Tumors were downstaged in 25 (49%) subjects receiving neoadjuvant therapy, 24% were clinical complete responders, and 20% were pathologic complete responders. The mean total lymph node harvest was 12.1 nodes per patient. Twenty-five subjects had positive nodal disease on final pathology. The sentinel lymph node detection rate was 85%, with a mean sentinel lymph node harvest of 2.2 nodes per subject. Fifteen (26%) subjects had sentinel lymph node nodal metastasis on routine hematoxylin and eosin examination. Neither multilevel sectioning nor immunohistochemistry evaluation improved detection of sentinel lymph node positivity. The accuracy of sentinel lymph node mapping was 71%, the sensitivity was 53%, the negative predictive value was 79%, and the false negative rate was 47%. Seven subjects were determined to have nodal disease only in the sentinel lymph node.

CONCLUSION

Ex vivo sentinel lymph node mapping is feasible after proctectomy for rectal cancer but did not improve staging. Neither multilevel sectioning nor immunohistochemistry improved the sensitivity of sentinel lymph node mapping.