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The Sentinel Lymph Node in Gastric Cancer.

Romeo Giuli MD, resident.
School of General and Emergency Surgery.
University of Siena.   Italy.

May 2001.     Review Article.
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Only a few studies have investigated the lymphatic flow system of GI cancers from the point of view of the sentinel node concept, which should not be confused with interpretation of previous studies on GI lymphology.
It is important to determine the value of this procedure in an accurate staging and in a minimally invasive approach to gastric cancers (Kitagawa).

In T1 gastric cancer (depth of cancer invasion limited in the mucosal or submucosal layer ) the incidence of nodal involvement is reported to be as low as 2% to 18% , and in the T2 gastric cancer ( cancer invading the muscular or subserosal layer) that incidence is about 50%.
Therefore Hiratsuka et al. consider if D2 lymphadenectomy is larger than necessary in a considerably high proportion of T1 and T2 gastric cancer patients, and if it is possible to find some reliable indicator that could predict the absence of lymph node metastases with high accuracy, eliminating major operations (proximal, distal or total gastrectomy) and the lymphadenectomy.

The authors use the dye method ( IGC) instead of the radionuclide method to detect the Sentinel node (the first node in the regional lymphatic basin that drains the primary tumor).
The perigastric nodes close to the primary tumor are generally the SNs and the use of the radionucleotide method implies an interference by the gamma rays emitted from the primary tumor located very close to these lymphatic metastasis.
This dye was injected around the tumor and was soon bound to albumin and carried specifically through the lymphatic vessels. The green-stained nodes were removed.
Then gastrectomy with extended lymphadenectomy was performed. Both SNs and non SNs were subjected to histologic examination with hematoxylin-eosin.

Only T1 and T2 gastric cancers were included in the study because the lymphatic flow would be easily altered when some of the main lymphatic routes were involved and occluded (Hiratsuka).

Moreover in the blue dye technique the time of injection of blue dye needs a carefull monitoring, because there is a short window of time during which selective identification of the SN is possible. For this reason Kitigawa et al affirm that a combination of intraoperative endoscopic injection of blue dye and gamma probe inspection (after endoscopic submucosal injection of radioactive tracer, - subserosal injection is difficult for realizing small and superficial lesions, that are not palpable from the serosal side-) is helpful for localizing sentinel nodes in gastric cancer. For confirming the complete resection of sentinel nodes a survey of the abdominal cavity by a gamma-detecting probe is essential (Kitagawa).

Hiratsuka reports that the success rate of SN detection was as high as 99%, with only 1 false negative . Because this false-negative case was T2 gastric cancer, it is prudent to state to apply SN biopsy to T1 gastric cancer patients and not to T2 gastric cancer patients.

This technique may be very helpful in the less invasive surgical treatments of EGCs ( wedge resection, segmental gastrectomies and EMRs). Because the method of SN detection using IGC is possible under laparoscopic operation it can be combined with the less invasive operations.

Hiratsuka hopes for more careful methods for the detection of lymph node metastases in SNs and non SNs (serial sectioning, immunohistochemistry, genetic diagnosis) and for studies on the intraoperative detection of metastases in SN by frozen section or imprint cytology or both (Hiratsuka).

In the Tsioulias's study lymphatic mapping was performed in 65 patients with GI neoplasms by injecting 0,5 to 1 ml of isosulfan blue dye around the periphery of the neoplasms. Blue stained SNs were analysed by hematoxilin-eosin staining, multiple sectioning, and cytokeratin immunohistochemistry.

The author underlines that the LM can identify aberrant lymphatic drainage, which may alter the extent of resection.
Aberrant drainage patterns are not uncommon in patients with GI neoplasms, and they are a possible explanation for inadequate staging and a patient's failure to respond to adjuvant treatment (Tsioulias).
Kosaka reports skip metastases in 15% of 51 patients with gastric cancer (Kosaka).

Moreover there is an inverse relationship between a GI neoplasm' s T stage and the presence of isolated LN metastases. The SN was the only positive node in all T1, 70% of the T2, 26% of the T3 and 20% of the T4 neoplasms.
Therefore SN analysis may be particularly relevant in identifying micrometastatic spread from T1-T2 tumors.
The clinical significance of these micrometastasis is under discussion (see next article of Surgical Oncology net).

Tsioulias concludes that in the meantime LM with focused examination of the SNs (on serial sectioning and IHC) improves the staging of GI neoplasms and may affect the selection of the patients for adjuvant therapy (Tsioulias).

Eventually, according to the Maruyama opinion, the ability to identify a tumor free SN might enable the surgeon to avoid the morbidity associated with radical lymphadenectomy in patients with gastric cancer. But he concludes that it is too early to apply sentinel node biopsy for reducing the extent of lymphadenectomy for gastric cancer because of the complicated anatomy of lymphatic streams from the stomach, and because of frequent skip metastasis and micrometastasis (Maruyama).


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George J Tsioulias , Thomas F. Wood, Donald L Morton, Anton J Bilchik. Lymphatic mapping and focused analysis of sentinel lymph nodes upstage gastrointestinal neoplasms. Arch Surg 2000; 135: 926-932.

Kosaka T et al. Lymphatic routes of the stomach demonstrated by gastric carcinomas with solitary lymph node metastasis. Surg Today. 1999; 29: 695-700.

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Morton DL et al. Technical details of intraoperative lymphatic mapping for early stage melanoma. Arch Surg 1992; 127:392-9.

Giuliano AE et al. Improved axillary stage of breast cancer with sentinel lymphadenectomy. Ann Surg 1995; 222: 394-399.

Giuliano AE et al. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg. 1994; 220: 391-401.

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