Utilización del ganglio centinela en patología digestiva

The role of sentinel lymph node in colon cancer evolution

INTRODUCTION

The aim of this study is to evaluate the sentinel lymph node mapping (SLNM) with methylene blue staining "ex vivo" in colon cancer, as well as calculate the upstaging obtained by the determination of micrometastases and its correlation with the evolution of the disease.

METHODS

Between 2008 and 2011, 101 patients with colon cancer undergoing resection were studied prospectively with SLNM and detection of micrometastases. The correlation of SLN micrometastases with the disease evolution was evaluated in patients with a follow-up of more than one year.

RESULTS

The SLNM rate was 92 cases (91%). Only SLN was positive for micrometastases in 9 cases, with a 14% upstaging. The incidence of false negatives was 9 patients (10%). Mean follow of N0 patients (n=74) was 38 months. The SLN- (negative) group (65 patients) had a recurrence rate of 4 patients (7%), whereas this rate was 2 patients (22%) in the group of SLN+(positive) (9 patients), but without significant differences. No differences in survival were observed.

CONCLUSIONS

SLNM is a reproducible technique without significant increase in time and costs. Upstaging was obtained in 14% of patients staged as N0 by conventional technique. At follow-up of N0 patients with SLN+there seems to be a higher rate of recurrence, which could change the guidelines of adjuvant treatment, but we must interpret the results it with caution because the sample is small.

[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.

[Not Available]

M. Pocard, J.-C. Sabourin In theory, the concept of sentinel lymph node (SLN) biopsy can be applied to cancer surgery for all solid cancers. Yet sentinel lymph node biopsy has not become a standard part of gastrointestinal cancer surgery. It has been of value in the assessment of small early-stage gastric cancers, but has only achieved widespread practice in Japan. Studies of SLN biopsy in colon cancer have not shown it to be a reliable predictor of N+ status and therefore don't permit the omission of lymph node dissection in selected cases. On the other hand, as a form of intra-operative lymph node mapping, dye injection of the SLN may demonstrate aberrant lymphatic drainage and could occasionally permit the sparing of a middle colic artery whose sacrifice would otherwise be dictated by standard drainage patterns. SLN biopsy may have prognostic usefulness by demonstrating micrometastases; careful serial sectioning focussed on the SLN may detect nests of metastatic cells on HE staining, thereby converting a tumor from Stage I (TxN0M0) to Stage II (TxN1M0). This finding has been noted in 10-15% of cases. However, the prognostic value of micrometastases detected only by immunohistochemical staining or PCR has not been demonstrated. For cancers of the anal canal, SLN biopsy of inguinal nodes has been tested as a means of establishing the indications for inguinal lymph node dissection.