Upstaging benefits and accuracy of sentinel lymph node mapping in colorectal adenocarcinoma nodal staging

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 one-step nucleic acid amplification in colorectal cancer lymph node metastases detection

Current histopathological staging procedures in colorectal cancer (CRC) depend on midline division of the lymph nodes (LNs) with one section of hematoxylin and eosin staining. Cancer cells outside this transection line may be missed, which could lead to understaging of Union for International Cancer Control Stage II high-risk patients. The one-step nucleic acid amplification (OSNA) assay has emerged as a rapid molecular diagnostic tool for LN metastases detection. It is a molecular technique that can analyze the entire LN tissue using a reverse-transcriptase loop-mediated isothermal amplification reaction to detect tumor-specific cytokeratin 19 mRNA. Our findings suggest that the OSNA assay has a high diagnostic accuracy in detecting metastatic LNs in CRC and a high negative predictive value. OSNA is a standardized, observer-independent technique, which may lead to more accurate staging. It has been suggested that in stage II CRC, the upstaging can reach 25% and these patients can access postoperative adjuvant chemotherapy. Moreover, intraoperative OSNA sentinel node evaluation may allow early CRC to be treated with organ-preserving surgery, while in more advanced-stage disease, a tailored lymphadenectomy can be performed considering the presence of aberrant lymphatic drainage and skip metastases.

Prognostic Impact of the Number of Examined Lymph Nodes in Stage II Colorectal Adenocarcinoma: A Retrospective Study

BACKGROUND

Evaluation of lymph node status is critical in colorectal carcinoma (CRC) treatment. However, as patients with node involvement may be incorrectly classified into earlier stages if the examined lymph node (ELN) number is too small and escape adjuvant therapy, especially for stage II CRC. The aims of this study were to assess the impact of the ELN on the survival of patients with stage II colorectal cancer and to determine the optimal number.

METHODS

Data from the US Surveillance, Epidemiology, and End Results (SEER) database on stage II resected CRC (1988-2013) were extracted for mathematical modeling as ELN was available since 1988. Relationship between ELN count and stage migration and disease-specific survival was analyzed by using multivariable models. The series of the mean positive LNs, odds ratios (ORs), and hazard ratios (HRs) were fitted with a LOWESS (Locally Weighted Scatterplot Smoothing) smoother, and the structural break points were determined by the Chow test. An independent cohort of cases from 2014 was retrieved for validation in 5-year disease-specific survival (DSS).

RESULTS

An increased ELN count was associated with a higher possibility of metastasis LN detection (OR 1.010, CI 1.009-1.011, p < 0.001) and better DSS in LN negative patients (OR 0.976, CI 0.975-0.977, p < 0.001). The cut-off point analysis showed a threshold ELN count of 21 nodes (HR 0.692, CI 0.667-0.719, p < 0.001) and was validated with significantly better DSS in the SEER 2009 cohort CRC (OR 0.657, CI 0.522-0.827, p < 0.001). The cut-off value of the ELN count in site-specific surgeries was analyzed as 20 nodes in the right hemicolectomy (HR 0.674, CI 0.638-0.713, p < 0.001), 19 nodes in left hemicolectomy (HR 0.691, CI 0.639-0.749, p < 0.001), and 20 nodes in rectal resection patients (HR 0.671, CI 0.604-0.746, p < 0.001), respectively.

CONCLUSIONS

A higher number of ELNs are associated with more-accurate node staging and better prognosis in stage II CRCs. We recommend that at least 21 lymph nodes be examined for accurate diagnosis of stage II colorectal cancer.

Perioperative PET/CT lymphoscintigraphy and fluorescent real-time imaging for sentinel lymph node mapping in early staged colon cancer

Purpose

Using current optical imaging techniques and gamma imaging modalities, perioperative sentinel lymph node (SLN) identification in colon cancer can be difficult when the SLN is located near the primary tumour or beneath a thick layer of (fat) tissue. Sentinel lymph node mapping using PET/CT lymphoscintigraphy combined with real-time visualization of the SLN using near-infrared imaging has shown promising results in several types of cancer and may facilitate the successful identification of the number and location of the SLN in early colon cancer.

Methods

Clinical feasibility of PET/CT lymphoscintigraphy using preoperative endoscopically injected [⁸⁹Zr]Zr-Nanocoll and intraoperative injection of the near-infrared (NIR) tracer Indocyanine Green (ICG) was evaluated in ten early colon cancer patients. Three preoperative PET/CT scans and an additional ex vivo scan of the specimen were performed after submucosal injection of [⁸⁹Zr]Zr-Nanocoll. All SLNs and other lymph nodes underwent extensive pathological examination for metastases. A histopathological proven lymph node visible at preoperative PET/CT and identified at PET/CT of the specimen was defined as SLN.

Results

A total of 27 SLNs were harvested in seven out of eight patients with successful injection of both tracers. In one patient no SLNs were assigned preoperatively. In two patients injection of [⁸⁹Zr]Zr-Nanocoll failed due to incorrect needle positioning. Twenty-one (78%) SLNs were found intraoperatively using NIR-imaging. Eleven of the 27 (41%) SLNs were located near the primary tumour (< 2 cm). Those six SLNs not found intraoperatively with NIR-imaging were all located close to the tumour. In all seven patients at least one SLN could be assigned at preoperative imaging 24 h after tracer administration. One SLN contained metastases detected by immunohistochemistry. No metastases were found in the non-SLNs.

Conclusions

This study shows the potential of preoperative PET/CT lymphoscintigraphy to inform the surgeon about the number and location of SLNs in patients with early colon cancer. The additional use of NIR-imaging allows for intraoperative identification of these SLNs which are invisible with conventional white light imaging. Further research is necessary to improve and simplify the technique. We recommend perioperative SLN identification using a preoperative lymphoscintigraphy scan just before surgery approximately 24 h after injection. Additionally a postoperative scan of the specimen combined with intraoperative real-time NIR-imaging should be performed.

Electronic supplementary material

The online version of this article (10.1007/s00259-019-04284-w) contains supplementary material, which is available to authorized users.

[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.

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.

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.

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.

One hundred consecutive cases of sentinel lymph node mapping in colon cancer-the results of prospective, single--centre feasibility study with implementation of immunohistochemical staining

PURPOSE

Although the importance of sentinel node biopsy (SNB) in colon cancer (CC) has not been clearly established, this method is proposed as potentially enabling more appropriate staging by means of immunohistochemistry (IHS). The aim of the study was to evaluate the SNB method used in CC treatment taking into consideration the results of the IHS examination.

MATERIALS AND METHODS

In the period from May 2005 to September 2010 in the 1st Department of Surgical Oncology and General Surgery, Wielkopolska Cancer Centre, 100 SNB in CC were performed. Sentinel nodes (SN) were identified intraoperatively with the use of Patent Blue dye. In the case of negative hematoxylin and eosin staining, the SN material was subjected to immunohistochemical examination. Finally, the histopathological findings of sentinel and non-sentinel lymph nodes were compared with the results of the immunohistochemical staining.

RESULTS

At least one SN was identified in 99 of 100 patients (99%). The SN was the only place of metastases in 12.1% (12/99) of the patients. The accuracy of SNB in determining the regional lymph node status was 93.9% (93/99). The sensitivity of the method was 83.3% (30/36). The false-negative rate amounted to 16.7% (6/36). Upstaging obtained by the implementation of the immunohistochemical method was 10% (7/70).

CONCLUSIONS

The application of the immunohistochemical staining enables upstaging of some patients, potentially benefiting from adjuvant chemotherapy. For full and definitive assessment of SNB in CC, further research is required especially in terms of additional factors determining a patient's eligibility for this procedure.

Review of histopathological and molecular prognostic features in colorectal cancer

Prediction of prognosis in colorectal cancer is vital for the choice of therapeutic options. Histopathological factors remain paramount in this respect. Factors such as tumor size, histological type and subtype, presence of signet ring morphology and the degree of differentiation as well as the presence of lymphovascular invasion and lymph node involvement are well known factors that influence outcome. Our understanding of these factors has improved in the past few years with factors such as tumor budding, lymphocytic infiltration being recognized as important. Likewise the prognostic significance of resection margins, particularly circumferential margins has been appreciated in the last two decades. A number of molecular and genetic markers such as KRAS, BRAF and microsatellite instability are also important and correlate with histological features in some patients. This review summarizes our current understanding of the main histopathological factors that affect prognosis of colorectal 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.

Suggestion of optimal patient characteristics for sentinel lymph node mapping in colorectal adenocarcinoma

CONTEXT

In a previously published study, the variables lower rectal tumor site, preoperative chemoradiotherapy and large tumors were considered as independent risk factors for the inability of sentinel lymph node identification in patients with colorectal adenocarcinoma.

OBJECTIVES

To determine if these variables could interfere in the precision and upstaging benefit of sentinel lymph node mapping in colorectal cancer.

METHODS

A database composed of 52 patients submitted to lymphatic mapping using technetium-99m-phytate and patent blue was reviewed. Only patients with tumors smaller than 5.0 cm, not submitted to preoperative chemoradiotherapy and without lower rectal cancer were included.

RESULTS

With these parameters, 11 patients remained to be studied. The sentinel lymph node identification rate was 100%, with a sensitivity of 100%, negative predictive value of 100%, no false negatives and accuracy of 100%. Sentinel lymph nodes were the only metastatic nodes in 36.4% of the patients, micrometastases (<0.2 cm or only identified by immunohistochemistry) provided an upstaging rate of 27.1% and metastases an upstaging rate of 9.1%.

CONCLUSION

The parameters proposed in this study for selection of colorectal adenocarcinoma patients to be submitted to sentinel lymph node mapping identified optimal accuracy and good upstaging results. As the number of included patients was low, these results could serve as guidance for proper patient selection in further prospective lymph node mapping studies in colorectal cancer patients.

The optimal number of lymph nodes examined in stage II colorectal cancer and its impact of on outcomes

Background

Lymph node status is the most important prognostic factor for colorectal cancer. The number of lymph nodes that should be histologically examined has been controversial. The aims of this study were to assess the impact of the number of lymph nodes examined on survival of patients with stage II colorectal cancer and to determine the optimal number of lymph nodes that should be examined.

Methods

The study included 664 patients who underwent resection for stage II colorectal cancer. The clinical and histopathologic data of the patients were prospectively collected and analyzed.

Results

The median number of lymph nodes examined was 12 (range: 1 to 58). The 5-year disease free survival rate was significantly higher for patients with 12 or more lymph nodes examined compared to those with less than 12 lymph nodes examined. The significant difference in 5-year disease free survival persisted if the dividing number increased progressively from 12 to 23. However, the difference in survival was most significant (lowest p value and highest hazard ratio) for the number 21. The 5-year disease free survival of patients with 21 or more lymph nodes examined was 80% whereas that of patients with less than 21 lymph nodes examined was 60% (p = 0.001, hazard ratio 2.08). Multivariate analysis showed that 21 or more lymph nodes examined was a factor that independently influenced survival. The 5-year disease free survival also increased progressively with the number of lymph node examined up to the number 21. After the number 21, the survival rate did not increase further. It was likely that 21 was the optimal number, at and above which the chance of lymph node metastasis was minimal.

Conclusions

The number of lymph nodes examined in colorectal cancer specimen significantly influences survival. It is recommended that at least 21 lymph nodes should be examined for accurate diagnosis of stage II colorectal cancer.

Retroperitoneal and lateral pelvic lymphadenectomy mapped by lymphoscintigraphy for rectal adenocarcinoma staging

BACKGROUND

The good prognosis of retroperitoneal and lateral pelvic lymphadenectomy has raised the question of whether total mesorectal excision is suitable for adequate staging of rectal adenocarcinoma patients. The aims of this study were to determine the accuracy of dye and probe detection of metastatic retroperitoneal and/or lateral pelvic nodes and to define the upstaging impact of retroperitoneal and lateral pelvic lymphadenectomy in rectal adenocarcinoma patients.

METHODS

Ninety-seven rectal adenocarcinoma patients were submitted to total mesorectal excision and retroperitoneal and lateral pelvic lymphadenectomy. Lymphoscintigraphy using technetium-99 m-phytate and patent blue was performed to detect blue and/or radioactive retroperitoneal and/or lateral pelvic nodes which were examined histopathologically and immunohistochemically with a step-sectioning technique.

RESULTS

Mesorectal mean node count was 11.5 and retroperitoneal and/or lateral pelvic node was 11.7. Retroperitoneal and lateral pelvic lymphadenectomy identified metastases in 17.5%, upstaging 8.2%. Variables related to metastatic retroperitoneal and/or lateral pelvic nodes were the following: Stage III in total mesorectal excision specimens (P < 0.04), pT3/pT4 tumors (P = 0.047), high levels of carcinoembryonic antigen (P = 0.014) and large tumors (P = 0.03). Marker migration to retroperitoneal and/or lateral pelvic nodes occurred in 37.1%, upstaging 11.1%. The markers' accuracy in the detection of metastatic retroperitoneal and/or lateral pelvic nodes was 100%.

CONCLUSIONS

Retroperitoneal and lateral pelvic lymphadenectomy detected an important rate of metastatic retroperitoneal and/or lateral pelvic nodes (RLPN), resulting in upstaging. When markers migrated, they were able to detect RLPN metastases. The use of markers should be improved in the identification of RLPN metastases for selective indication of retroperitoneal and lateral pelvic lymphadenectomy.

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.

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.