Accurate staging and prognostication of stage I to II pure-solid non-small cell lung cancer (NSCLC) should include 18 examined lymph nodes (ELNs) and 6 examined node stations (ENSs), according to results from a study published in the Journal of the National Comprehensive Cancer Network.
Whether lymph nodes should be examined or the number that should be examined from early-stage NSCLC undergoing lobectomy is not clear. The differing opinions make it “important to determine the threshold of ELNs and ENSs for early-stage NSCLC, especially for radiologically pure-solid NSCLC,” the authors wrote. The aim of this study was to evaluate the relationship between long-term survival and the extent of lymph node dissection.
The study analyzed data from 1205 patients from 6 institutions in China with radiologically pure-solid cT1a-2bN0-1M0 NSCLC who underwent lobectomy and ipsilateral lymphadenectomy. Researchers evaluated nodal upstaging, stage migration, recurrence-free survival (RFS), and overall survival (OS) with regard to the extent of ELNs and ENSs. They used a LOWESS smoother to fit endpoints with ELNs or ENSs to determine the threshold needed for accurate staging.
Both ELNs and ENSs were independently prognostic for survival during a median follow-up of 68 months. In a multivariate analysis, ELNs were significantly associated with OS (hazard ratio [HR] 0.95 [95% CI, 0.92-0.98]; P <.004) and RFS (HR 0.96 [95% CI, 0.94-0.96]; P <.001). Examined node station were also significantly associated with OS (HR 0.69 [95% CI, 0.6-0.8]; P <.001) and RFS (HR 0.86 [95% CI, 0.79-0.93]; P <.001).
ELNs and ENSs were also significantly associated with nodal upstaging (P ≤.004), with a higher number of ELNs and ENSs linked to greater accuracy of nodal staging and a lower risk for stage migration.
The investigators examined threshold of ELNs and ENSs across endpoints. They identified cut points of 18 ELNs and 7 ENSs for stage migration, 15 ELNs and 6 ENSs for finding a positive lymph node, and 18 ELNs and 6 ENSs for OS.
The authors selected cutoff values of 18 ELNs and 6 ENSs, which the patient cohort validated. All-cause mortality was significantly lower among patients with ≥18 ELNs or 6 ENSs.
The authors concluded that “both ELNs and ENSs are associated with accurate staging and survival outcomes in radiologically pure-solid NSCLC.” They added that “a threshold of 18 lymph nodes and 6 stations might be considered for evaluating the quality of lymph node examination.”
Chen D, Mao Y, Wen J, et al. Impact of the extent of lymph node dissection on precise stating and survival in clinical I-II pure-solid lung cancer undergoing lobectomy. J Nath Compr Canc Netw. Published online January 28, 2021. doi: 10.6004/jnccn.2020.7635