Ex vivo sentinel lymph node "mapping" in colorectal cancer

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.

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.

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.

The influence of micrometastases on prognosis and survival in stage I-II colon cancer patients: the Enroute⊕ Study

Background

The presence of lymph node metastases remains the most reliable prognostic predictor and the gold indicator for adjuvant treatment in colon cancer (CC). In spite of a potentially curative resection, 20 to 30% of CC patients testing negative for lymph node metastases (i.e. pN0) will subsequently develop locoregional and/or systemic metastases within 5 years. The presence of occult nodal isolated tumor cells (ITCs) and/or micrometastases (MMs) at the time of resection predisposes CC patients to high risk for disease recurrence. These pN0_micro+ patients harbouring occult micrometastases may benefit from adjuvant treatment. The purpose of the present study is to delineate the subset of pN0 patients with micrometastases (pN0_micro+) and evaluate the benefits from adjuvant chemotherapy in pN0_micro+ CC patients.

Methods/design

EnRoute+ is an open label, multicenter, randomized controlled clinical trial. All CC patients (age above 18 years) without synchronous locoregional lymph node and/or systemic metastases (clinical stage I-II disease) and operated upon with curative intent are eligible for inclusion. All resected specimens of patients are subject to an ex vivo sentinel lymph node mapping procedure (SLNM) following curative resection. The investigation for micrometastases in pN0 patients is done by extended serial sectioning and immunohistochemistry for pan-cytokeratin in sentinel lymph nodes which are tumour negative upon standard pathological examination. Patients with ITC/MM-positive sentinel lymph nodes (pN0_micro+) are randomized for adjuvant chemotherapy following the CAPOX treatment scheme or observation. The primary endpoint is 3-year disease free survival (DFS).

Discussion

The EnRoute+ study is designed to improve prognosis in high-risk stage I/II pN0 _micro+ CC patients by reducing disease recurrence by adjuvant chemotherapy.

Trial Registration

ClinicalTrials.gov: NCT01097265

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.

The Feasibility of an Ex-vivo Sentinel Lymph Mapping Using Preoperative Radioisotope Injection in Cases of Extraperitoneal Rectal Cancer

PURPOSE

The purpose of this research was to evaluate the feasibility of sentinel lymph node (SLN) mapping involving transanal injection with an ex-vivo mapping in patients with rectal cancer.

METHODS

Between April 2007 and December 2009, 20 consecutive patients with T1-3, N0-1 clinical stage rectal cancer preoperatively underwent a SLN procedure using submucosal (99m)Tc-phytate injection. All the patients underwent a total mesorectal excision. After the standard surgical resection, all specimens were identified on lymphoscintigraphy, and bench work was done to pick up the sentinel node basin. All the lymph nodes (non-SLNs and SLNs) were examined using conventional hematoxylin and eosin staining and immunohistochemistry with anti-cytokeratin antibodies.

RESULTS

SLNs were identified from 19 of 20 patients with rectal cancer. The total number of sentinel nodes retrieved from the surgical specimens was 29, and the mean number per patient was 1.6 (range, 0 to 4). In three patients, the SLN was the only positive lymph node. There was one false-negative case with a sensitivity of 88.8% and two upstaged cases (20.0%). The SLN samples from rectal cancer are mainly localized in the pararectal region, but aberrant nodes receive direct drainage from the rectal cancer. On planar lymphoscintigraphy, 15.7% of all patients had aberrant lymphatic drainage to the sigmoid mesenteric or sigmoid lymph node station.

CONCLUSION

In conclusion, the intraoperative transanal injection for ex-vivo SLN navigation is a safe, feasible surgical modality in patients with rectal cancer. Large studies are warranted to determine the clinical significance of the SLN concept and micrometastasis in rectal cancer.

Clinical translation of ex vivo sentinel lymph node mapping for colorectal cancer using invisible near-infrared fluorescence light

Background

Sentinel lymph node (SLN) mapping in colorectal cancer may have prognostic and therapeutic significance; however, currently available techniques are not optimal. We hypothesized that the combination of invisible near-infrared (NIR) fluorescent light and ex vivo injection could solve remaining problems of SLN mapping in colorectal cancer.

Methods

The FLARE imaging system was used for real-time identification of SLNs after injection of the NIR lymphatic tracer HSA800 in the colon and rectum of (n = 4) pigs. A total of 32 SLN mappings were performed in vivo and ex vivo after oncologic resection using an identical injection technique. Guided by these results, SLN mappings were performed in ex vivo tissue specimens of 24 consecutive colorectal cancer patients undergoing resection.

Results

Lymph flow could be followed in real-time from the injection site to the SLN using NIR fluorescence. In pigs, the SLN was identified in 32 of 32 (100%) of SLN mappings under both in vivo and ex vivo conditions. Clinically, SLNs were identified in all patients (n = 24) using the ex vivo strategy within 5 min after injection of fluorescent tracer. Also, 9 patients showed lymph node involvement (N1 disease). In 1 patient, a 3-mm mesenteric metastasis was found adjacent to a tumor-negative SLN.

Conclusions

The current pilot study shows proof of principle that ex vivo NIR fluorescence-guided SLN mapping can provide high-sensitivity, rapid, and accurate identification of SLNs in colon and rectum. This creates an experimental platform to test optimized, non-FDA-approved NIR fluorescent lymphatic tracers in a clinical setting.

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.

Improving lymph node detection in colon cancer in community hospitals and their pathology department in southern Netherlands

AIM

The aim was to investigate whether a set of measures directed at increasing lymph node (LN) detection among colon cancer patients led to clinically relevant changes in LN detection rate.

METHODS

Data of all patients with curative colon cancer (pT(any) N(any) M0) diagnosed in 1999-2007 whose resection specimens were evaluated by the Institute for Pathology and Medical Microbiology in Eindhoven (n=1501) were included. Feedback to specialists, increased fixation time, and ex-vivo injection of the specimen with Patent blue V dye were used to increase LN detection rate. Trends in the proportion of patients with insufficient LNs examined were investigated; moreover, the Patent blue-stained patients (n=86) were compared with a group of unstained patients (n=84). Based on the decrease in the proportion of high-risk node-negative patients, a calculation of chemotherapy-related costs saved was made.

RESULTS

The proportion of patients with <12 LNs examined decreased from 87% in 1999 to 48% in 2007 (p(trend)<0.0001). In the stained group this was 37%, versus 56% for the unstained group (p=0.010). In 1999, 79% of stage II patients were high-risk compared to 55% in 2007, which translates to a saving of almost 1,000,000 euro based on 92 stage II patients diagnosed in 2007.

CONCLUSION

A diverse set of measures increased the number of examined lymph nodes among patients with colon cancer. Large savings can be made due to the reduced proportion of high-risk node-negative patients who would otherwise have received adjuvant chemotherapy.

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.