Clinicopathological and survival outcomes of 4L lymph node dissection in left lung adenocarcinoma and squamous cell carcinoma

Background

Whether 4L lymph node dissection (LND) should be performed remains unclear and controversial. Prior studies have found that station 4L metastasis was not rare and that 4L LND may provide survival benefits. The objective of this study was to analyze the clinicopathological and survival outcomes of 4L LND from the perspective of histology.

Methods

This retrospective study included 74 patients with squamous cell carcinoma (SCC) and 84 patients diagnosed with lung adenocarcinoma (ADC) between January 2008 and October 2020. All patients underwent pulmonary resection with station 4L LND and were staged as T1-4N0-2M0. Clinicopathological features and survival outcomes were investigated based on histology. The study endpoints were disease-free survival (DFS) and overall survival (OS).

Results

The incidence rate of station 4L metastasis was 17.1% (27/158) in the entire cohort, with 8.1% in the SCC group, and 25.0% in the ADC group. No statistical differences in the 5-year DFS rates (67.1% vs. 61.7%, P=0.812) and 5-year OS rates (68.6% vs. 59.3%, P=0.100) were observed between the ADC group and the SCC group. Multivariate logistic analysis revealed that histology (SCC vs. ADC: OR, 0.185; 95% CI, 0.049-0.706; P=0.013) was independently associated with 4L metastasis. Multivariate survival analysis showed that the status of 4L metastasis was an independent factor for DFS (HR, 2.563; 95% CI, 1.282-5.123; P=0.008) but not for OS (HR, 1.597; 95% CI, 0.749-3.402; P=0.225).

Conclusion

Station 4L metastasis is not rare in left lung cancer. Patients with ADC have a greater predilection for station 4L metastasis and may benefit more from performing 4L LND.

The impact of left lower paratracheal (4L) lymph node dissection on survival in patients with surgically treated left-sided NSCLC

OBJECTIVES

We aimed to investigate the clinical significance of left lower paratracheal nodes (#4L) and their impact on survival in patients with left-sided lung cancer.

METHODS

This was a retrospective analysis of prospective data. The study included 5369 patients who underwent surgery between 2005 and 2015. Six hundred fifty-nine patients underwent #4L dissection (4LND+), and 4710 did not (4LND-). Propensity score matching was used to minimize analytic error (659 vs 659).

RESULTS

The percentage of #4L metastasis increased with tumour size. Between pT2a and pT2b, it nearly doubled from 8% to 14%. The mean percentage of #4L metastasis in the pN2 group was 46, which was higher in left upper lobectomy compared to left lower lobectomy (63% vs 43%, respectively, P < 0.001). In univariable analysis, no differences in 5-year survival were observed between 4LND+ and 4LND- (48% vs 50%, respectively, P = 0.65). However, we detected a significant difference among non-metastatic 4LND+, 4LND- and metastatic 4LND+ (P < 0.0001). After propensity score matching, there were no significant differences in survival among the pN2 subgroups (pN2a1, pN2a2, pN2b1, pN2b2). Multivariable analysis after propensity score matching for each pN2 subgroup did not confirm the effect of #4L metastasis as an independent prognostic factor.

CONCLUSIONS

Despite #4L nodes not being an independent prognostic factor in lung cancer, the percentage of nodal metastases notably increases above pT2a grade and is comparable to the percentage of #5 and #7 metastasis. Therefore, lymphadenectomy in advanced stages of cancer could benefit from resections of the #4L nodes.

[Clinicopathological characteristics and risk factors of station 4L lymph node metastasis of left non-small cell lung cancer]

OBJECTIVE

To analyze the clinicopathological characteristics and risk factors of 4L lymph node metastasis in left non-small cell lung cancer.

METHODS

We retrospectively analyzed the data of 134 patients undergoing surgical resection of left non-small cell lung cancer and 4L lymph node dissection, including 60 patients with squamous cell carcinoma (SCC) and 74 with lung adenocarcinoma (ADC). The clinicopathological characteristics of the patients were analyzed, and logistic regression analysis was used to identify the predictors of station 4L metastasis.

RESULTS

Of these patients, 16.4% (22/134) presented with station 4L metastasis. The patients with SCC and ADC showed significant differences in age, gender, smoking history, neoadjuvant chemotherapy, tumor size, tumor location and type, visceral pleural invasion, Ki-67 index, 4L metastasis and pathological TNM stage (stage Ⅱ). The rate of station 4L metastasis was significantly lower in SCC group than in ADC group. Univariate analysis revealed that pathological types (SCC or ADC), visceral pleural invasion, lymphovascular invasion, tumor markerabnormality, and station 5 to 10 metastasis were all high-risk factors for station 4L metastasis. Multivariate analysis suggested that the pathological type (OR=0.120, P=0.025), station 5 metastasis (OR=18.784, P=0.007) and station 10 metastasis (OR=5.233, P=0.044) were independent risk factors for 4L metastasis in patients with left non-small cell lung cancer.

CONCLUSIONS

In patients with left non-small cell lung cancer, station 4L metastasis is not rare and is more likely to occur in patients with lung adenocarcinoma. Dissection of the 4L lymph nodes should be performed in cases with low risk of damages of the adjacent tissues and high risk of station 4L metastasis.