Lymph node pickup is usually performed by a surgeon or pathologist after surgery for gastric cancer, with the goal of obtaining lymph nodes from the resection specimen and then sending them for pathology, where the pathologist can determine whether each lymph node has metastases and stage them accordingly.
Precise staging is the key to postoperative prognosis and adjuvant therapy selection for gastric cancer, and lymph node harvesting is an important part of achieving accurate staging. According to the American Joint Committee on Cancer (AJCC) TNM staging guidelines for gastric cancer, a minimum of 16 lymph nodes is required, and this is usually the standard in our hospitals.
A high number of lymph nodes recovered suggests a relatively good prognosis
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A high number of lymph node collections has been reported in the literature to indicate a better prognosis, but the reasons for this phenomenon are not well understood. It has been suggested that this is due to “staging migration,” a concept that is not easy to explain, but simply means that patients with relatively few lymph node collections may have missed lymph nodes and their staging may be inaccurate, whereas patients with relatively many lymph node collections are more accurately staged. In this case, the patient who is judged to have the same staging may in fact deserve to be judged to have a worse prognosis in terms of the number of lymph nodes picked up, and this misjudgment leads to a poor relative prognosis for that patient when compared with patients who are judged to have the same staging.
However, two points need to be emphasized. One is that “staging migration” is only a theory, and it is not necessarily correct. The other point is that the number of lymph node collections is highly influenced by individual patient variability, with factors such as patient age, tumor location, and whether or not preoperative neoadjuvant therapy was administered affecting the number of lymph node collections. Therefore, if the number of lymph node collections in the postoperative pathology report is low or even less than 16, this is not direct evidence that the surgery was incomplete or that the pathology was not meticulous.
The use of adjuncts does not affect the accuracy of lymph node retrieval
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Sometimes, to increase the number of lymph nodes picked up and to try to examine them more accurately, the clinician or pathologist may use methylene blue (Methylthioninium Chloride) injections, the addition of lipolytic solution, or even the latest optical molecular imaging. All of these techniques may help with lymph node retrieval, but the evidence supporting these methods is not yet sufficient, and they are not routinely recommended in national and international guidelines. Therefore, whether or not the physician performs such procedures does not have a direct impact on the accuracy of pathological findings in gastric cancer.
The number of lymph node collections is not used as a basis for postoperative treatment at this time
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There is insufficient evidence that the number of lymph node collections is a guide to postoperative treatment, and therefore, in general, the number of lymph node collections does not influence postoperative treatment decisions. In exceptional cases, physicians may use a more intense postoperative adjuvant regimen for some patients with a low lymph node count when making postoperative adjuvant treatment decisions, but this decision will be made in the context of the patient’s other conditions and based on the physician’s experience. (Contributed by Peng Gao, Department of Gastrointestinal Oncology, The First Affiliated Hospital of China Medical University)