Sentinel node mapping does not improve staging of lymph node metastasis in colonic 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.

Sentinel lymph node mapping for metastasis detection in colorectal cancer: a systematic review and meta-analysis

INTRODUCTION

controversy exists on the diagnostic performance of sentinel lymph node (SLN) mapping in colorectal cancer. This study aimed to provide a more precise estimation of its clinical significance.

MATERIALS AND METHODS

a systematic search of electronic databases was conducted to retrieve all relevant studies up to August 31st, 2019. Detection rate, sensitivity, and upstaging rate were pooled together, and a subgroup analysis was performed to identify factors that affect diagnostic performance. The prognostic value of upstaging was also explored.

RESULTS

sixty-eight studies were eligible and included. The pooled SLN detection rate was 0.93 (95 % CI, 0.91-0.94), with a significant higher rate in colon cancer or in studies including more than 100 patients. The overall sensitivity of the SLN procedure in colorectal cancer was 0.72 (95 % CI, 0.67-0.77). The tracers used were found to influence sensitivity. A mean weighted upstaging of 0.22 (95 % CI, 0.18-0.25) was identified. True upstaging, defined as micro-metastases, was 14 %. Upstaged patients were associated with worse overall survival (OS) when compared with node-negative patients (HR = 2.60, 95 % CI, 0.16-4.63). In addition, upstaged patients had a lower 5-year disease-free survival (DFS) rate than node-negative patients.

CONCLUSION

based on the results of the present meta-analysis, the SLN mapping procedure should focus on early stage patients to refine staging, since upstaging appeared to be a prognostic factor for DFS and OS. The SLN procedure can be recommended for colorectal cancer patients in addition to conventional resection.

Ex vivo sentinel lymph node mapping in colorectal cancer using a magnetic nanoparticle tracer to improve staging accuracy: a pilot study

AIM

Nodal status is the most important prognostic factor in colorectal cancer (CRC). Small occult metastases may remain undetected on conventional histopathological examination, potentially resulting in undertreatment. Ex vivo sentinel lymph node mapping (SLNM) can be used to improve the accuracy of nodal staging, but the currently used tracers suffer from drawbacks, which hamper implementation of the technique in routine clinical practice. Magnetic tracers are the optimal size for sentinel lymph node (SLN) retention and allow objective quantitative selection of SLNs; they therefore have great potential for SLNM in CRC. The study evaluates the feasibility of ex vivo magnetic SLNM and compares the performance of this technique with blue dye SLNM.

METHOD

Twenty-eight ex vivo SLNM procedures were performed in 27 histological node-negative patients with CRC using a magnetic tracer and blue dye. A magnetometer was used to select magnetic SLNs after formalin fixation of the CRC specimen. Both magnetic and blue SLNs were subjected to serial sectioning and immunohistochemical staining to reveal occult metastases.

RESULTS

At least one SLN was successfully identified in 27/28 (96%) and 25/28 (89%) of the cases with the magnetic technique and blue dye. Isolated tumour cells were detected in 10 patients. This was predicted with 100% sensitivity and accuracy using the magnetic technique, and with 91% sensitivity and 96% accuracy using the blue dye technique.

CONCLUSION

This study demonstrates that ex vivo magnetic SLNM is a feasible technique for use in routine clinical practice, improving nodal staging accuracy of CRC patients.

Management of nodal disease from colon cancer in the laparoscopic era

PURPOSE

In colon cancer (CC), nodal involvement is the main prognostic factor following potentially curative (R0) resection. The purpose of this study was to examine data from the literature to provide an up-to-date analysis of the management of nodal disease with special reference to laparoscopic treatment.

METHODS

MEDLINE and EMBASE databases were searched for potentially eligible studies published in English up to July 15, 2014.

RESULTS

In CC, nodal involvement is a frequent event and represents the main risk of cancer recurrence. Node negative patients recur in 10-30 % of cases most likely due to underdiagnosed or undertreated nodal disease. Extended colonic resections (complete mesocolic excision with central vascular ligation; D3 lymphadenectomy) provides a survival benefit and better local control. Sentinel lymph node mapping in addition to standard surgical resection represents an option for improving staging of clinical node negative patients. Both extended resection and sentinel lymph node mapping are feasible in a laparoscopic setting.

CONCLUSIONS

Both extended colonic resection and sentinel lymph node mapping should play a role in the laparoscopic treatment of CC with the purpose of improving control and staging of nodal disease.

Laparoscopic sentinel lymph node identification in patients with colon carcinoma using a near-infrared dye: description of a new technique and feasibility study

BACKGROUND

After promising results were obtained from studies in large animals, a technique using indocyanine green (ICG) is being introduced for sentinel lymph node (SLN) biopsy in colon cancer patients.

SUBJECTS AND METHODS

Colon cancer patients without clinical signs of metastatic disease, presenting at the VU University Medical Center (Amsterdam, The Netherlands) or Kennemer Gasthuis (Haarlem, The Netherlands), were asked to participate in the study. During laparoscopy, a subserosal injection of 2.5 mg of ICG diluted in 1 mL of 0.9% NaCl plus 2% human albumin was performed using a percutaneously inserted long rigid or flexible needle. After injection, a near-infrared laparoscope (Olympus Corp., Tokyo, Japan) was used for lymph flow and SLN visualization. The SLNs were laparoscopically harvested and analyzed by a senior pathologist using multisectioning and immunohistochemistry.

RESULTS

Fourteen patients were included (six women, eight men), with a median age of 75.5 (interquartile range [IQR], 67.8-81.0) years and a median body mass index of 25.1 (IQR, 22.7-26.0) kg/m(2). Median tumor diameter was 4.5 (IQR, 3.4-7.0) cm. At least one SLN was identified in all patients, with a median number of 2.0 (IQR, 2.0-3.3) SLNs. The median time between injection and identification of the SLN was 15.0 (IQR, 13.3-29.3) minutes. Positioning of the needle tip into the subserosal layer was found to be more effective using the flexible needle. When this flexible needle was used, less spill of dye was observed. All SLNs were negative. We observed four false-negative nodes, all after using a rigid needle. None of the patients showed an adverse reaction to the ICG injection.

CONCLUSIONS

Preliminary results of laparoscopic sentinel node identification using a near-infrared dye show this procedure is safe and feasible. It was possible to detect lymph nodes in all patients. Large tumor size, drainage to adjacent lymphatic vessels, and the use of a rigid needle might contribute to false-negative nodes.

Prognostic relevance of occult metastases detected by cytokeratin 20 and mucin 2 mRNA levels in sentinel lymph nodes from colon cancer patients

PURPOSE

To investigate the prognostic value of occult metastases detected by quantitative measurements of candidate biomarkers in sentinel lymph nodes (SLNs) from patients curatively resected for colon cancer.

METHODS

Resection specimens from consecutive patients undergoing surgery for localized colon cancer were subjected to ex vivo SLN mapping. SLNs were examined for the presence of metastases by routine hematoxylin-erythrosin-safranin staining and by cytokeratin 20 (CK20) and mucin 2 (MUC2) mRNA quantification. The patients were stratified according to KRAS and BRAF mutation status and microsatellite instability status in their primary tumors. Survival end points were analyzed by Kaplan-Meier survival estimates and log-rank tests.

RESULTS

A total of 817 SLNs were identified in 206 (97 %) of the 213 included patients. Routine histological examination of SLNs and other regional lymph nodes identified 63 patients with positive nodes (pN+), of which 42 (67 %) were positive in one or more SLNs (sensitivity 67 %, false-negative rate 33 %). On the basis of the CK20 and MUC2 mRNA levels in SLNs, occult metastases were suggested in 86 (60 %) and 52 (36 %) of the 143 otherwise LN-negative (pN0) patients, respectively. Survival analysis with a median 3.6-year follow-up revealed that MUC2 mRNA quantification had significant prognostic value in SLNs from all patients; however, occult SLN metastasis detection did not.

CONCLUSIONS

Occult SLN metastases detected by CK20 and MUC2 mRNA quantification had limited prognostic value.

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.

Ex vivo sentinel lymph node mapping in laparoscopic resection of colon cancer

AIM

The study examined the feasibility and potential benefit of ex vivo sentinel lymph node (SLN) mapping, including multilevel sectioning (MLS) and immunohistochemistry (IHC) in colon cancer patients undergoing laparoscopic colectomy. The secondary goals were (i) to identify patient and tumour characteristics that might influence the success of the SLN technique, (ii) to investigate the extent of lymphadenectomy required to encompass tumour-positive nonsentinel lymph nodes (NSLN) and (iii) to ascertain the association of SLN status with oncological outcomes.

METHOD

SLN mapping was performed after specimen extraction using 1% Isosulfan blue. The SLNs were analysed with H&E staining after MLS, and if negative, IHC was performed. NSLNs were grouped by distance either greater than or less than 4 cm from the tumour.

RESULTS

Seventy-one patients completed the study between 2003 and 2007. Using H&E with MLS, the accuracy of SLN mapping was 76%, sensitivity was 52% and the false-negative rate was 48%. Excluding patients with clinically positive lymph nodes resulted in a significant improvement in accuracy to 81% and decreased the false-negative rate to 30%. Furthermore, as the only positive NSLN > 4 cm from the tumour was grossly positive, SLN mapping with a 4-cm mesenteric cuff would have given 100% sensitivity in patients without macroscopically involved nodes.

CONCLUSIONS

SLN mapping may be of value in selected patients. It may be possible to accurately stage patients with a 4-cm cuff of mesentery, although further validation of this proposal is required.

Clinical value of sentinel node mapping in carcinoma of the colon

AIM

Sentinel lymph node mapping has been used in colon cancer to improve prognosis. This study aimed to determine the accuracy of in vivo SLNM in patients with colon carcinoma undergoing surgery with curative intent.

METHOD

Thirty-one patients operated for colon carcinoma underwent in vivo sentinel lymph node mapping using patent blue dye. Each sentinel lymph node (SLN) was marked intraoperatively, and histological examination was performed after en bloc resection. If no metastasis was found, step sectioning with immunohistochemistry was performed.

RESULTS

The SLN was successfully identified in 28 (90%) of 31 patients. The false-negative rate to identify stage III disease was 66% (eight of 12), the negative predictive value was 46% (19 of 27) and the accuracy was 14% (four of 28). One patient negative on routine histopathology had micrometastasis on step sectioning of the SLN.

CONCLUSION

Sentinel lymph node mapping in colon carcinoma cannot accurately predict nodal status.

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.

Lymph node micrometastases and isolated tumor cells influence survival in stage I and II colon cancer

PURPOSE

Lymph-node status is considered the most important prognostic factor in colorectal cancer. The aim of the present prospective study was to evaluate the influence of micrometastases and isolated tumor cells on recurrence and disease-free survival in colon cancer.

METHODS

A total of 193 patients with colon cancer, operated on between 2000 and 2005, were enrolled in the study. All lymph nodes were examined by routine microscopy in hematoxylin and eosin-stained sections. If no metastases were identified in any node, all nodes were examined immunohistochemically with monoclonal antibody CAM 5.2.

RESULTS

Ordinary metastases were found in 67 patients, leaving 126 patients in stage I/II. Immunohistochemistry showed that 5% (6/126) of these had micrometastases and 26% (33/126) had isolated tumor cells. A median of 5 years of follow-up revealed local or distant recurrence in 23% (9/39) of stage I/II patients with micrometastases or isolated tumor cells, compared with 7% (6/87) without micrometastases or isolated tumor cells (P = .010). Five-year disease-free survival for patients with and without micrometastases or isolated tumor cells was 75% and 93%, respectively (P = .012). When analyzed separately, patients with isolated tumor cells (excluding micrometastases) had also lower survival than node-negative patients (P = .012).

CONCLUSION

The presence of micrometastases and isolated tumor cells was found to be a prognostic factor for recurrence and disease-free survival. This may have implications for future treatment of stage I/II colon cancer.

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.

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.

Diagnosing occult tumour cells and their predictive value in sentinel nodes of histologically negative patients with colorectal cancer

PURPOSE

Most studies on the sentinel node (SN) procedure in patients with colorectal cancer include immunohistochemical analysis of the SN only. To evaluate the real diagnostic accuracy of the SN procedure with immunohistochemical analysis, the presence of occult tumour cells in all histologically negative lymph nodes was compared to the presence of these cells in SNs. Also the reproducibility of diagnosing occult tumour cells (OTC) and the sensitivity of three different antibodies was assessed.

METHODS

Between November 2006 en July 2007, an ex vivo SN procedure was performed in 58 histologically N0 patients with colorectal cancer. All lymph nodes (n = 908, mean 15.7) were step-sectioned and immunohistochemistry was performed using two antibodies against cytokeratins (Cam5.2, and CK 20) and one antibody against BerEp-4.

RESULTS

OTC were identified in 19 of 58 patients, with micrometastases (0.2-2 mm) in 7 and isolated tumour cells (ITC)(<0.2 mm) in 12 patients. The overall agreement in diagnosing OTC between two independent pathologists was 86%. An SN was identified in 53 of 58 patients. All micrometastases were found in SNs. In two patients with negative SNs, ITC's were demonstrated in non-SNs (sensitivity 88%, and overall accuracy 96%).

CONCLUSION

Additional immunohistochemical analysis of histologically negative lymph nodes demonstrates occult tumour cells in 33% of the patients resulting in an upstaging rate of 12%. Occult tumour cells are predominantly found in the SN, therefore SN mapping has the potential to refine the staging system for patients with colorectal cancer.

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

BACKGROUND

The technique of sentinel lymph node (SLN) mapping in patients with colorectal cancer varies between reports, and the optimal method has not been established. The purpose of this study was to determine the optimal injection technique for SLN mapping.

METHODS

Sixty-nine consecutive patients who underwent curative surgery for colorectal cancer were enrolled. The SLNs was identified intraoperatively by subserosal blue dye injection (in vivo) or by submucosal injection after standard colectomy (ex vivo). If negative by conventional hematoxylin and eosin staining analysis, all lymph nodes, SLNs and non-SLNs, were subjected to further analysis by multi-level section and immunohistochemical examination.

RESULTS

The in vivo and ex vivo injected groups were similar in demographic character, tumor size, and histological grade. The mean number of SLNs identified was 2.3 in the in vivo group and 2.6 in the ex vivo group (p = 0.192). The detection rate of SLNs by blue dye injection was somewhat higher in the ex vivo group than in the in vivo group: 90.6 vs. 81.1% (p = 0.219). The false-negative rate was 23.5% for the in vivo group and 13.3% for the ex vivo group (p = 0.392). The upstaging rate, which was 18.5% overall, was similar in both groups (p = 0.538).

CONCLUSIONS

These findings suggest that ex vivo blue dye injection is an effective alternative to in vivo injection for identifying SLNs in patients with colorectal cancer. Because of its simplicity and applicability in routine clinical settings, further investigation of the ex vivo mapping technique is warranted.

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.

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.