Advances in locating lymph nodes by endoscopic ultrasound-guided fine-needle marking

In the pretreatment setting for upper gastrointestinal tumors, locating lymph nodes and accurate diagnosis of their status is still a challenge. Despite progress with modern imaging technologies, including computed tomography (CT), magnetic resonance imaging (MRI), endoscopic ultrasound (EUS), and positron emission tomography (PET), as well as sentinel lymph node biopsy, no method has been established that accurately predicts node location and status. The development of such a method may have clinical implications for decision-making about the selection of optimal treatment.

To evaluate the feasibility, safety, and efficacy of node location, Larsen and colleagues [1] performed a prospective study published recently in Endoscopy. A new EUS-guided fine-needle technique for marking lymph nodes was evaluated in 25 patients with suspected or confirmed malignancies of the upper gastrointestinal tract. The EUS-guided fine-needle marking (EUS-FNM) was done using a silver pin; the position of the pin was verified by EUS. End points were the identification and isolation of the marked lymph node during surgery.

A total of 23 lymph nodes were marked, and in 18 of 19 patients (95 %) in whom surgical isolations were performed, the lymph nodes were isolated in the resection specimens. The lymph nodes were isolated in the same topographical location as predicted by EUS in 84 % of the cases; one pin (5 %) was not retrieved. In three cases, a small hematoma was observed, and there was no sign of long-term complications.

What are the clinical implications of this study? Can the results of this study influence surgical and adjuvant practice? The authors note that ”Small tumors with no signs of lymph node metastasis can undergo curative surgical resection, whereas patients presenting with local advanced tumors or nodal metastasis often will benefit from neoadjuvant chemoradiotherapy … EUS-FNA is currently the best modality for differentiating between malignant and benign lymph nodes.”

However, there are many factors that limit the clinical utility of this EUS-FNM method. First, the number of lymph nodes and patients evaluated were too small to draw conclusions. Second, for gastric cancer, not only in Japan but also in many specialized Western institutions, standardized extensive (D2) lymphadenectomy is used in day-to-day clinical practice [2]. Given that this involves removal of all lymph nodes of level I (stations 1 – 6) and level II (7 – 12), the EUS-FNM technique is of less value. Third, even regarding decisions about neoadjuvant treatment, this technique has limited clinical power. In Japan and at several specialized hospitals in the EU and USA, primary D2 surgery followed by postoperative adjuvant chemotherapy or chemoradiotherapy is the standard of care [3] [4]. Not every larger sized lymph node contains metastases; in contrast, lymph nodes even smaller than 1 cm may be involved or have micrometastatic disease or isolated tumor cells. Another limitation is that the EUS-FNM technique can only be applied to gastrointestinal tract nodes. For more distant nodes, for example the level II nodes in gastric cancer, this technique cannot be used.

Competing interests: No research support for this letter.

References

• 1 Larsen M H, Fristrup C W, Pless T. et al . Endoscopic ultrasound-guided fine-needle marking of lymph nodes.  Endoscopy. 2009;  [Epub ahead of print]
• 2 Sasako M, Sano T, Yamamoto S. et al . Japan Clinical Oncology Group. D2 lymphadenectomy alone or with para-aortic nodal dissection for gastric cancer.  N Engl J Med. 2008;  359 453-462
• 3 Sakuramoto S, Sasako M, Yamaguchi T. et al. for the ACTS-GC Group . Adjuvant chemotherapy for gastric cancer with S-1, an oral fluoropyrimidine.  N Engl J Med. 2007;  357 1810-1820. Erratum in: N Engl J Med 2008; 358 : 1977
• 4 Catalano V, Labianca R, Beretta G D. et al . Gastric cancer.  Crit Rev Oncol Hematol. 2009;  71 127-164