A lymph node collection kit may help surgeons attain complete resection and improve long-term survival after curative-intent lung cancer surgery, according to a recent study published by Matthew Smeltzer, PhD, and colleagues in JTO Clinical and Research Reports.
Surgical resection is the most important curative treatment for non–small cell lung cancer (NSCLC). With successful implementation of lung cancer screening programs, the proportion of patients with NSCLC who undergo surgery is likely to increase significantly.
“However, poor surgical quality reduces the survival benefit of curative-intent surgery, and suboptimal pathologic nodal evaluation is the most prevalent NSCLC surgery quality deficit. The problem is global, and prevalent across institutions of different characteristics,” said Dr. Smeltzer, of the University of Memphis School of Public Health.
The International Association for the Study of Lung Cancer (IASLC) has proposed a revision of the residual disease (R-factor) classification, from complete (R0), microscopic incomplete (R1), and grossly incomplete (R2) to R0, ‘R-uncertain’, R1, and R2. The adverse prognostic impact of R-uncertainty has been independently validated, with the majority caused by poor nodal evaluation.
“We previously demonstrated longer survival after surgical resection with a lymph node specimen collection kit … and now evaluate R-factor redistribution as the mechanism of its survival benefit,” Dr. Smeltzer said.
“A lymph node kit increased overall survival by increasing R0 and reducing the probability of R-uncertain resections; and also by diminishing extreme R-uncertainty.”— Matthew Smeltzer, PhD, and colleagues
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More About the Kit and Resection Classification
The kit includes 12 anatomically prelabeled specimen containers and a checklist to indicate certain lymph node stations mandated for examination.
“We designed it to improve the intraoperative retrieval of lymph nodes compatible with evidence-based guidelines, the secure transfer of lymph node specimens between surgery and pathology teams, and the accurate identification of the anatomic provenance of lymph node specimens to encourage thorough and accurate pathologic evaluation,” he said.
An ongoing National Institutes of Health–funded, population-based Dissemination and Implementation project (2 R01 CA172253), the Mid-South Quality of Surgical Resection (MSQSR) project involves 15 hospitals in Eastern Arkansas, North and Central Mississippi, and Western Tennessee. The principal investigator, Ray Osarogiagbon, MD, of Baptist Memorial Health Care Corporation, is a member of the IASLC’s Staging and Prognostic Factors Committee. In this particular analysis, Dr. Smeltzer and his co-researchers analyzed 3,505 lung resections that took place between 2009 and 2019 from the MSQSR cohort.
Of 3,505 resections, 34% were R0, 60% R-uncertain, and 6% R1/2. The R0 percentage increased from 9% in 2009 to 56% in 2019. Kit cases were 66% R0 and 29% R-uncertain, compared to 14% R0 and 79% R-uncertain in nonkit cases (P < .0001).
“Compared to nonkit resections, kit resections had 12.6 times the adjusted odds of R0 vs R0 uncertain,” reported Dr. Smeltzer.
Kit cases also had lower percentages of nonexamination of lymph nodes (ie, pNX)—1% vs 14% (P < .0001)—and nonexamination of mediastinal lymph nodes—8% vs 35% (P < .0001). With the kit, more R-uncertain cases had examination of stations 7 (43% vs 22%, P < .0001) and 10 (67% vs 45%, P < .0001).
The adjusted hazard ratio for kit cases vs nonkit cases was 0.75 (confidence interval [CI] = 0.6–0.85, P < .0001); adjusted hazard ratio for R0 vs R-uncertain was 0.78 (CI = 0.69–0.88, P < .0001). In 2,100 subjects with R-uncertain resections, kit cases had an adjusted hazard ratio of 0.79 vs nonkit cases (CI = 0.64–80.99, P = .0384); however, in the 1,199 R0 resections, the survival difference was not significant (adjusted hazard ratio: 0.85, CI = 0.68–1.07, P = .17).
Dr. Smeltzer pointed out that a more carefully controlled trial is planned to corroborate these results. “Ultimately, the main limitation of this study is that it was not a randomized controlled trial. We propose to conduct such a trial to further evaluate the lymph node kit,” he said.
The study authors concluded, “A lymph node kit increased overall survival by increasing R0 and reducing the probability of R-uncertain resections; and also by diminishing extreme R-uncertainty.”
Disclosure: For full disclosures of the study authors, visit jtocrr.org.
