The American College of Surgeons Commission on Cancer currently mandates the sampling of three mediastinal (N2) lymph node stations and one hilar (N1) station with each lung cancer resection
Historically, much of the data and research have largely focused on examining N2 lymph nodes during lung cancer surgery, leaving N1 lymph node sampling relatively underexplored. However, findings from a retrospective, real-world study, presented as the J. Maxwell Chamberlain Memorial Paper in General Thoracic Surgery during the 2026 Society of Thoracic Surgeons (STS) Annual Meeting, indicate that N1 nodal assessment may be more important than it has been given credit for.
“We hypothesized a more extensive N1 lymph node assessment would help us find more unrecognized cancer in the lymph nodes of patients undergoing lung cancer surgery,” said Christopher Seder, MD, Rush University Medical Center, Chicago.
Closing a Knowledge Gap
Using the STS database, this study examined 48,779 patients with clinically node-negative non-small cell lung cancer (NSCLC) who underwent varying extents of nodal assessment.1
“We saw this as a gap in our knowledge base that should be investigated. Having the largest audited and most accurate thoracic database in the world at our fingertips, we felt this was an opportunity to advance knowledge in the field,” Dr. Seder said.
The study recorded the number of N1 and N2 lymph nodes sampled in each patient and evaluated upstaging rates—that is, the number of patients with occult, unrecognized, or “surprise” lymph node disease.1 The cohort included 30,369 patients who underwent wedge resection (18.5%), segmentectomy (17.1%), or lobectomy (64.4%).1
“We found a very clear trend: the more N1 lymph nodes that were removed, sampled, or examined, the higher the rates of upstaging. As the number of N2 lymph nodes increased, the benefit—or the increased amount of occult nodal disease identified—was not as impressive,” Dr. Seder said. “From this, we concluded that there should be a greater focus on N1 lymph node sampling than there currently is.”
The assessment of more than one N1 nodal station, including intrapulmonary nodal stations (stations 12–14), was associated with an increased rate of nodal upstaging, with an overall pathologic nodal upstaging rate of 11.2%.1
Additionally, the findings revealed that the incremental increase in nodal upstaging rate was greater with each additional N1 station assessed than with each additional N2 station assessed, without affecting major perioperative morbidity.1 Nearly one in five patients (19.7%) were upstaged due to malignancy identified exclusively in intrapulmonary lymph nodes (stations 12–14).1
The findings also emphasize the importance of N1 node sampling, regardless of the type of resection performed. In the primary analysis, which was adjusted for the specific procedure conducted in each patient, the association between increased N1 sampling and higher upstaging rates remained consistent and significant across all resection types.1
“This should not be interpreted as a reason to change your operation,” Dr. Seder said. “It should be interpreted as: whatever operation you feel is best, perform that operation, but then remove more N1 lymph nodes.”
Is There a “Magic Number” When it Comes to Lymph Node Sampling?
Although the findings clearly indicate that there is a correlation between the number of N1 nodal stations assessed and upstaging, challenges remain that make it difficult to determine the optimal number of N1 stations a surgeon should sample.
“Our data show that three lymph nodes are better than two, and two are better than one. However, we recognize that there are practical reasons why many surgeons may have difficulty finding three N1 stations,” Dr. Seder said. “Sometimes, there simply isn’t lymph node tissue available in certain areas.”
Additionally, not all tumors are the same, which makes it even more difficult to adopt a one-size-fits-all approach.
“For a very aggressive tumor with high-risk features, it may be more important to sample more N1 stations than for a small, peripheral, non-aggressive tumor, where outcomes might be excellent without extensive sampling,” Dr. Seder said.
He noted that future research will aim to analyze the data by tumor characteristics.
A Call to Action
Dr. Seder emphasized that these findings are not intended to challenge or dispute the standards set by the American College of Surgeons or the Commission on Cancer. Instead, they aim to provide additional information for experts to consider when revising guidelines.
“This is truly a call to action—both for thoracic surgeons, who should be assessing more N1 lymph node stations during lung cancer surgery, and for pathologists, whose responsibility is to dissect the specimen and identify lymph nodes hidden within the lung,” Dr. Seder said. “By retrieving more N1 nodes, we can identify more cancer and improve staging accuracy. Both the surgeon and the pathologist have crucial roles to play.”
Implementing these findings into practice will require effective coordination and communication between thoracic surgeons and pathologists. Studies have shown that pathology-specific protocols and educational sessions on identifying lymph nodes can improve nodal detection. Additionally, processes such as using labeled boxes for lymph node stations have contributed to more thorough lymph node sampling during surgery.
“Our hope is that these data will be seen by pathologists and that protocols and processes can be instituted to improve N1 nodal identification,” he said.
References
- 1. Seder C. J. Maxwell Chamberlain Memorial Paper in General Thoracic Surgery: Association Between Nodal Assessment, Upstaging, and Survival in Resected Clinically Node-negative Non-small Cell Lung Cancer. https://bit.ly/4cttfXP
