[Optimization of staging in colon cancer using sentinel lymph node biopsy]

Sentinel Lymph Node Mapping with Isosulfan Blue or Indocyanine Green in Colon Cancer Shows Comparable Results and Identifies Patients with Decreased Survival: A Prospective Single-Center Trial

BACKGROUND

Sentinel lymph node (SLN) mapping was reported to improve lymph node staging in colon cancer. This study compares isosulfan blue (IB) with indocyanine green (ICG)-based SLN-mapping and assesses the prognostic value of isolated tumor cells (ITC) and micro-metastases in upstaged patients.

METHODS

A total of 220 stage I-III colon cancer patients were included in this prospective single-center study. In 170 patients, SLN-mapping was performed in vivo with IB and in 50 patients ex vivo with ICG. Three levels of each SLN were stained with H&E. If negative for tumor infiltration, immunostaining for cytokeratin (AE1/3; cytokeratin-19) was performed.

RESULTS

SLN detection rate for IB and ICG was 100 and 98%, respectively. Accuracy and sensitivity was 88 and 75% for IB, 82 and 64% for ICG, respectively (p = 0.244). Overall, 149 (68%) patients were node negative. In these patients, ITC and micro-metastases were detected in 26% (31/129) with IB and 17% (5/29) with ICG (p = 0.469). Patients with ITC and micro-metastases did show decreased overall survival (hazard ratio = 1.96, p = 0.09) compared to node negative disease.

CONCLUSIONS

This study demonstrates a high diagnostic accuracy for both the IB and the ICG SLN-mapping. SLN-mapping upstaged a quarter of patients with node negative colon cancer, and the detected ITC and micro-metastases were an independent negative prognostic marker in multivariate analysis.

Comparing the efficacy of routine H&E staining and cytokeratin immunohistochemical staining in detection of micro-metastasis on serial sections of dye-mapped sentinel lymph nodes in colorectal carcinoma

BACKGROUND

The significance of techniques used for detecting micro-metastasis (MM) or isolated tumor cells (ITCs) is a controversial issue among investigators. We evaluated the different techniques used on sentinel lymph node (SLN) to detect MM/ITCs.

MATERIALS AND METHODS

Ninety-one SLNs of 15 patients underwent serial section with 100 μm interval. In each level, two sections were prepared. One section was stained with H&E and another with anti-cytokeratin antibody (immunohistochemistry). Then the sections were evaluated for detecting MM/ITCs. Results were analyzed by chi-square test.

RESULTS

1656 sections of 91 SLNs of 15 patients were evaluated by a pathologist; MM was found in 1 and ITCs in 1 case. Overall, 2 out of 15 cases (13.3% of the patients) showed MM/ITCs by IHC staining. So, serial section along with using IHC was superior than serial section and routine H&E staining. But it did not affect the 5-year survival of the patients (P = 0.47).

CONCLUSION

Using the combined techniques of serial section and IHC staining could up-stage 13.3% of colon cancer patients who were lymph node negative. In other studies with different combination of serial section, IHC staining, and PCR, investigators were able to find MM/ITCs in 3-39% of the cases. In our study, although serial section and IHC staining could up-stage 13.3% of patients, it could not affect the 5-year survival of the patients.

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

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

FUNDING

Cancer Center Amsterdam Foundation, Amsterdam, Netherlands.

Sentinel lymph node biopsy for gastrointestinal cancers

Sentinel lymph node biopsy (SLNB) in gastrointestinal-(GI)-tract cancer is not yet of clinical relevance. Nevertheless, the results in the upper GI-tract promise to be helpful to individualize the indication for surgical therapy. SLNB in colon cancer still fails to show high validity to predict the nodal status, but may be helpful to clarify the prognostic role of micrometastases/isolated tumor cells. In anal cancer SLNB is able to guide the indication for groin irradiation.

Sentinel lymph node biopsy in colon cancer: a prospective multicenter trial

INTRODUCTION

The clinical impact of sentinel lymph node biopsy (SLNB) in colon cancer is still controversial. The purpose of this prospective multicenter trial was to evaluate its clinical value to predict the nodal status and identify factors that influence these results.

METHODS

Colon cancer patients without prior colorectal surgery or irradiation were eligible. The sentinel lymph node (SLN) was identified intraoperatively by subserosal blue dye injection around the tumor. The SLN underwent step sections and immunohistochemistry (IHC), if classified free of metastases after routine hematoxylin and eosin examination.

RESULTS

At least one SLN (median, n = 2) was identified in 268 of 315 enrolled patients (detection rate, 85%). Center experience, lymphovascular invasion, body mass index (BMI), and learning curve were positively associated with the detection rate. The false-negative rate to identify pN+ patients by SLNB was 46% (38 of 82). BMI showed a significant association to the false-negative rate (P < 0.0001), the number of tumor-involved lymph nodes was inversely associated. If only slim patients (BMI < or =24) were investigated in experienced centers (>22 patients enrolled), the sensitivity increased to 88% (14 of 16). Moreover, 21% (30 of 141) of the patients, classified as pN0 by routine histopathology, revealed micrometastases or isolated tumor cells (MM/ITC) in the SLN.

CONCLUSIONS

The contribution of SLNB to conventional nodal staging of colon cancer patients is still unspecified. Technical problems have to be resolved before a definite conclusion can be drawn in this regard. However, SLNB identifies about one fourth of stage II patients to reveal MM/ITC in lymph nodes. Further studies must clarify the clinical impact of these findings in terms of prognosis and the indication of adjuvant therapy.

Detection of lymph node micrometastases and isolated tumor cells in sentinel and nonsentinel lymph nodes of colon cancer patients

About 20% to 30% of colon cancer patients classified as node negative by routine hematoxylin-eosin (H&E) staining are found to have micrometastases (MM) or isolated tumor cells (ITC) in sentinel lymph nodes (SLNs) if analyzed by step sections and immunohistochemistry (IHC). Whether SLNs are in this respect representative for all lymph nodes was addressed in this study. SLNs were identified using the intraoperative blue dye detection technique. If all lymph nodes (SLNs and non-SLNs) of a patient were negative by routine H&E staining, they were step-sectioned and analyzed by IHC using pancytokeratin antibodies. We identified at least one SLN in 47 of the 55 patients (85%) and examined a median of 26 lymph nodes per patient (range 10-59). By routine H&E staining, 14 of the 47 patients showed lymph node metastases (30%); the remaining 33 were classified as node-negative. In this group (33 patients), 1011 lymph nodes were analyzed by step sections and IHC: 14 of 70 SLNs. (20%) but only 37 of 941 non-SLNs (4%) had MM/ITC (p < 0.001). Furthermore, 13 of the 33 H&E-negative patients were found to have MM/ITC (39%). In 11 of the 13 patients, MM/ITC were identified in both SLNs and non-SLNs in 1 patient in the SLN only, and in 1 patient in a non-SLN only (sensitivity for the identification of MM/ITC: 92%; negative predictive value: 95%). The SLN biopsy is a valid tool to detect, as well as exclude, the presence of MM/ITC in colon cancer patients. Our results may be of prognostic relevance and influence patient stratification for adjuvant therapy trials.