Finding Lymph Nodes With Carbon Nanoparticle Suspension Injection

Taking into account that the stage of the disease at the time of diagnosis is considered to be one of the main factors in long-term survival among patients with gastric cancer, an adequate clinical evaluation, together with a correct initial clinical staging, could allow surgery to be ideally combined with neoadjuvant chemotherapy or adjuvant radiochemotherapy, aiming to provide each patient with a gastric tumor with the best-suited treatment according to their particular needs. In this sense, all measures taken to enhance pathological staging will be crucial in improving the prognosis of the disease.

In this effort, in the recent years, different dyes and tracers have been studied to observe lymph node (LN) drainage from primary tumors. In the case of gastric cancer, carbon nanoparticle suspension injection (CNSI) and indocyanine green (ICG) have been applied both intraoperatively to facilitate lymphatic mapping and postoperatively to sort LNs in the retrieved pathological specimens. Studies have shown that ICG improves the number of LN dissections and reduces LN nonadherence without increased complications in patients undergoing D2 lymphadenectomy.^1,2 However, the need for a fluorescent laparoscopy system may limit its applicability worldwide. In contrast, CNSI can be performed under direct vision, which could help to obtain better LN classification results.³

Although evidence in the literature is still scarce and there is a lack of high-quality randomized clinical trials that evaluate the efficacy and safety of these tools, and although the study by Tian et al⁴ has some limitations, we believe it brings some light into the darkness. In their study, Tian et al⁴ analyze the tracing and diagnostic value associated with CNSI as an LN tracer technique in distal gastrectomy for gastric cancer. They have designed a retrospective, single-center, cohort trial of 257 patients who underwent laparoscopic or robotic distal gastrectomy with D1+ or D2 lymphadenectomy, of whom 78 in each group were analyzed after propensity score matching. The mean number of LNs detected was compared between groups, and the diagnostic role of CNSI was analyzed.

Tian et al⁴ concluded that CNSI, compared with conventional treatment, was associated with increasing the number of lymph nodes detected (mean [SD], 59.6 (21.4) LNs per patient vs 30.0 [11.3] LNs per patient; P < .001) and with reduced lymph node staging deviation between stained and unstained LN stations (mean [SD], 92 [6.1] LNs per station vs 3.5 [3.2] LNs per stations; P < .001), which suggest that CNSI facilitated the dissection of all positive LNs and improved overall surgical quality.

The retrospective nature of the study, as well as the absence of randomization, limit its statistical validity. However, in view of the promising results obtained, it would be interesting to design prospective randomized trials that could confirm these preliminary results. In addition, since IGC is currently one of the most widespread LN tracer methods used, it would also be of interest to compare in depth both methods. If they are confirmed to be similar, the use of CNSI, which should be less expensive and does not require fluorescence systems, could be of particular interest, especially in less-developed health systems or in hospitals that do not have the most technologically advanced methods. Making advances and improvements in cancer diagnosis, prognosis, and treatment available to everyone should be a top priority.

Complete perigastric lymphadenectomy is key in long-term survival of gastric cancer. It is fundamental for the accurate staging of tumors, the selection of subsequent treatment, and the improvement of prognosis.⁵ Experienced surgeons usually perform lymphadenectomy with the sole aid of their own experience. However, the complex vascular anatomy of the stomach and its lymphatic drainage can pose a challenge in the course of such a lymphadenectomy, especially for younger and less-experienced surgeons, and avoiding an increase in morbidity is fundamental. The development of tools that can facilitate a safer performance of this maneuver, and at the same time improve the accuracy of the lymph node dissection, is a field of great interest.

Accepted for Publication: February 28, 2022.

Published: April 18, 2022. doi:10.1001/jamanetworkopen.2022.7759

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2022 Curell A et al. JAMA Network Open.

Corresponding Author: Anna Curell, MD, Department of Gastrointestinal Surgery, Hospital Clínic de Barcelona, Villarroel 170, 08036 Barcelona, Spain (curell@clinic.cat).

Conflict of Interest Disclosures: Dr Balibrea reported receiving personal fees from Johnson & Johnson outside the submitted work. No other disclosures were reported.