Sentinel Node Biopsy

DR. Sergio Ralon

Even nowadays in the beginning of this century there is considerable debate as the use of extensive lymphadenectomy versus limited lymphadenectomy of the perigastric lymph nodes in cancer gastric (5,6,7,8). In the cases of Penile Cancer, Melanoma and now Breast Carcinoma the use of Sentinel Node have provided a rational use of selective lymphadenectomy (2,3,4,9). This study showed the first experience in our center trying to demonstrate that in Gastric Cancer it is possible use the same concept of Sentinel Node Biopsy and has a rational use of selective node dissection. In our Unit we have five years of rutinary use of D2 lymphadenectomy for operable Gastric cancer according to the guidelines o the Japanese research society for gastric cancer JRSGC (10). There are several studies showing an increase in morbidity and surgical time in patients with extensive lymphadenectomy (11, 12).

This study provides evidence on the sequence of the spread of the Gastric Cancer to the N1 and N2 nodes. The lymphatic mapping with blue dye is easy, cheap and there is not necessary a learning period as in Breast Cancer (13), The blue node is easy identifiable.

In the cases of Breast Cancer and Melanoma several vital blue dye have been used; Isosulphan blue is more commonly used in the United States and Patent blue in Europe. Some investigators have used methylene blue with bad results (13) but in our cases we did not have problems with this blue dye. We don’t have experience with the use on 99m Tc labeled colloids and gamma probe-guided surgery; maybe in the case of Gastric Cancer have advantages over our method in identified nodes in N2 and N3 levels. Our study demonstrated that the status of the Sentinel node might allow selective extensive lymphadenectomy (D2/D3) avoiding the morbidity and the increase in surgical time.

In the present study, the sentinel node was identified in 12/15 patients and was predictive of the lymph node status in 85%; we have 2 cases of false negative and 0 of false positive. Maybe the cases of failure in identified the sentinel node were due of inadequate injection of blue dye or inappropriate timing for starting the dissection. In Breast Cancer the cases of false negative have been reported due real skip metastases, sub optimal mapping or alterations in lymph-draining paths (13).

Other problems with the management of the sentinel node is the kind of pathologic staining; with the use of cytokeratin immunohistochemical staining the rate of sentinel nodes increase versus the conventional techniques (hematoxylin-eosin staining); with the use of molecular biology techniques such as RT-PCR increase the rate of true positive nodes (14,15).

In the future maybe will be possible use the frozen-section of the sentinel node to select which patients need an extensive lymphadenectomy; in that case for improve the reability of the intraoperative diagnosis could be used a technique for rapid inmunostaining with a cytokeratin marker as reported by Chilosi et al. (16) Others reported the used of imprint cytology preparations on the sentinel node as good method for the intraoperative diagnosis as is used for evaluations of the surgical margins (17).

Most of the cases the Sentinel Node was identified at location N1 in 84%, level 1(right cardial) in 2, level 2 (left cardial) in 1, level 3 (lesser curvature) in 1, level 4 (greater curvature) in 2, level 5 (suprapyloric) in 2, level 6 (infrapyloric) in 2; but in 16 % the Sentinel Node was identified at level 7 around the left gastric artery (N2 nodes), that was in the case of tumor located near the lesser curvature and posterior wall. This case maybe justified the D2 dissection in tumor at the posterior wall that the first lymph drain is at the second echelon lymph nodes and does not to the N1 chain.

At Japan as is reported by Maruyama and colleagues where the D2 lymphadenectomy is performed routinely operative morbidity and mortality is low (18), they have more than 30 years of experience in this procedure (10) and it is the standard of treatment in Gastric Cancer (19,20). However, several studies as the Dent’s group from South Africa, the group on Hong Kong an the Dutch trial demonstrated and increase in Morbidity, Mortality, length of hospitalization, transfusion requirements and longer operating time (21). Because of these reports some centers advocated the use of selective lymphadenectomy in base of the macroscopically suspicious nodes (23,24), but the problem is that even small nodes less of 3 mm are invaded as is reported by Noguchi and colleagues (25). For this reason the size of the nodes is a bad parameter for select which patients need extensive lymphadenectomy.

With this initial small series we presented an alternative, the Sentinel Node in Gastric Cancer as parameter in use of selective D2 lymphadenectomy.