Different prognostic significance of examined lymph node count for patients with non-small-cell lung cancer ≤1 cm or >1-2 cm: a population-based study

Effect of examining lymph nodes count on mortality risk in resected T1 non-small-cell lung cancer

OBJECTIVES

This study aims to estimate the effect of the examined lymph node count (ELNC) on the cancer-related mortality risk and non-cancer-related mortality risk in patients with resected T1 non-small-cell lung cancer (NSCLC).

METHODS

Patients diagnosed as primary T1 NSCLC between 2000 and 2017 were extracted from the Surveillance, Epidemiology and End Results database. Patients were divided into 2 groups according to the ELNC cutoff value, which was calculated based on overall survival outcomes. Propensity score matching was used to equalize the differences in baseline characteristics between groups.

RESULTS

A total of 38 242 resected T1 NSCLC patients were extracted from the database with the ELNC cutoff value of 8. After propensity score matching, 27 676 patients were included in this study. Examining ≥8 ELNC was associated with a more accurate assessment of lymph node (LN) metastasis and significantly improving the prognosis. These trends remained consistent in subgroup analysis by histology type. In competing risk mode, examining ≥8 LNs could significantly reduce the risk of death from lung cancer, risk of death from chronic obstructive pulmonary disease, and risk of death from cardiac diseases. In the subgroup analysis, these trends were consistent.

CONCLUSIONS

Given the mortality risk associated with lung cancer, chronic obstructive pulmonary disease, and cardiac diseases, at least 8 LNs should be examined in surgery for T1 NSCLC.

Exploration of the optimal number of regional lymph nodes removed for resected N0 NSCLC patients: A population-based study

Background

The aim of our study was to explore the optimal number of regional lymph nodes removed (LNRs) in resected N0 non-small cell lung cancer (NSCLC) patients and identify potential risk factors.

Methods

Included in this study were 55,024 N0 NSCLC patients between 2004 and 2015 based on the Surveillance, Epidemiology, and End Results database (SEER). All the patients were divided into No LNR group (57.8%), 1-3 LNRs group (8.1%) and ≥4 LNRs group (31.4%). Relevant clinical and patient parameters including overall survival (OS), lung cancer-specific survival (LCSS), gender, race, year of diagnosis, primary site, T stage, AJCC stage, laterality, histological type, lymphadenectomy, radiation, chemotherapy, age at diagnosis, insurance status, marital status, family income.

Results

Kaplan-Meier analysis demonstrated LNRs had significantly better OS and LCSS than No LNRs in all the N0 NSCLC patients with different T stages (Logrank p<.001). Univariate and multivariate analysis showed that both OS and LCSS in ≥ 4 LNRs group were better than those in <1-3 LNRs group (OS: ≥4 LNRs group: HR, 0.583; 95%CI, 0.556-0.610; P<.001 vs.1-3 LNRs group: HR, 0.726; 95%CI, 0.687-0.769; P<.001; LCSS: ≥4 LNRs group: HR, 0.514; 95%CI, 0.480-0.550; P<.001 vs.1-3 LNRs group: HR, 0.647; 95%CI, 0.597-0.702; P<.001). In addition, whites, males, not upper lobe, large cell carcinoma and others, advance T stage or AJCC stage, no surgery, no LNR, no radiation, no chemotherapy, elder age at diagnosis, singled marital status and low family income had negative impact on prognosis of N0 NSCLC patients.

Conclusions

Our study suggests that ≥ 4 LNRs can yield better survival outcomes compared with 1-3 LNRs in N0 NSCLC patients.