Single-station skip-N2 disease: good prognosis in resected non-small-cell lung cancer (long-term results in skip-N2 disease)

What alters prognosis in patients who were operated for lung cancer with lymph node metastasis?

INTRODUCTION

In this study, we investigated the clinical outcomes of patients who underwent surgery with proven lymph node metastasis.

METHODS

Patients who were operated for lung cancer with pN1 or pN2 were examined in the study. The clinicopathological features and survival of the subjects were evaluated according to pN1-pN2 status, presence of neoadjuvant treatment, Positron emission tomography and computed tomography (PET/CT) avidity on mediastinal lymph nodes and specific lymph node stations.

RESULTS

The study examines 100 patients operated from January 2016 to December 2021. Number of cases with pN1 and pN2 disease were 45 (45%) and 55 (55%) respectively. Thirty (30%) patients received neoadjuvant treatment. The 5-year overall survival (OS) and disease-free survival (DFS) of the patients were computed as 42.5% and 42.4% correspondingly. The 5-year cancer-related survival was 55.3%. In pN2 cohort, 5-year DFS was 67.9% in the neoadjuvant group and 15.9% in the non-neoadjuvant group (P = 0.042). In non-neoadjuvant group, 5-year DFS was 19.9% in cases with mediastinal PET/CT avidity and 56.3% in patients without mediastinal PET/CT avidity (P = 0.018). In pN2 disease, the presence of subcarinal or paratracheal lymph node metastasis did not create a significant difference in 5-year OS or DFS, but pulmonary ligament lymph node metastasis was found to be linked with worse survival in both 5-year OS (P = 0.005) and DFS (P = 0.017).

CONCLUSION

The main elements related with poor prognosis were absence of neoadjuvant treatment and pulmonary ligament lymph node metastasis in pN2 disease, detecting PET/CT avid mediastinal lymph nodes in non-neoadjuvant group.

Impact of skip mediastinal lymph node metastasis on outcomes after resection for primary lung cancer

OBJECTIVES

Patients with non-small cell lung cancer and nodal disease are a heterogeneous group with varied patterns of disease. The aim of this study was to assess long-term outcomes of patients with skip N2 disease in comparison to those with N1 or non-skip N2 disease.

MATERIALS AND METHODS

A retrospective review of 445 patients undergoing anatomical lung resection for primary lung cancer between 2012 and 2019 with post-operative histological confirmation of nodal disease was undertaken. Log rank analysis was used to assess differences in estimated median overall survival according to nodal status. Multivariable Cox regression analysis was performed to determine whether skip N2 disease was independently associated with overall survival.

RESULTS

Mean patient age was 67.0 years (standard deviation ± 9.2 years) and 48.1% (n = 214) were male. In total, 20.7% (n = 92) of patients had N1 disease, 32.1% (n = 143) had skip N2 disease and 47.2% (n = 210) had non-skip N2 disease. Post-operative upstaging took place in 33.0% (n = 147) of patients. Median follow-up time was 35 months (interquartile range 14-68 months). Skip N2 patients had significantly longer estimated median overall survival in comparison to their non-skip N2 counterparts (47 months vs 28 months, log rank analysis p = 0.029) and non-skip N2 disease remained independently associated with reduced overall survival after multivariable analysis (hazard ratio 1.421, 95% confidence interval 1.060-1.907, p = 0.019).

CONCLUSION

Skip N2 disease is a positive prognostic factor for patients with N2 lung cancer, suggesting that lung cancer staging guidelines should consider separating N2 disease into additional subgroups in order to improve prognostic accuracy.

Extracapsular extension of pN2 lymph node metastases is not prognostically significant in surgically resected patients with non-small cell lung cancer

Objectives

In patients with non-small cell lung cancer (NSCLC) the pathologic lymph node status N2 is a heterogeneous entity, with different degrees of lymph node involvement representing different prognoses. It is speculated whether extra capsular nodal extension may help to define a subgroup with implications on long-term survival.

Methods

We retrospectively identified 118 patients with non-small cell lung cancer (65 men, 53 women), who were treated between 2013 and 2018 and found to have pathologic N2 lymph node involvement. In all patients lung resection with systematic mediastinal and hilar lymph node dissection was performed with curative intent. In N2 lymph node metastases capsules of affected lymph nodes were examined microscopically as to whether extracapsular extension was present.

Results

51 patients (43 %) had extracapsular extension (ENE). Most of these patients (n=35) only had ENE in a single lymph node (69 %). The overall 5-year survival rate was 24.6 % and progression-free survival rate 17.8 %. In the multivariate analysis OS was worse for patients with multiple affected pN2 stations, concurrent N1 metastases, increasing age, and larger tumor size. For the percentage of lymph nodes affected with ENE (of total examined) only a non-significant trend towards worse OS could be observed (p=0.06).

Conclusions

Although we could not demonstrate significant prognostic differences between N2 extra capsular nodal involvement within our patient population, other analyses may yield different results. However, clinicians should continue performing thorough lymph nodes dissections in order to achieve local complete resection even in patients with extra capsular tumor spread.

[Review for N2 Sub-staging in Non-small Cell Lung Cancer]

Patients with N2 non-small cell lung cancer (NSCLC) were heterogeneous groups and required further stratification. The International Society for the Study of Lung Cancer (IASLC) divided N2 into three sub-stages: N2 at a single station without N1 involvement (N2a1), N2 at a single station with N1 involvement (N2a2), and N2 at multiple stations (N2b). These new descriptors significantly distinguished the overall survival (OS), disease-free survival (DFS), and recurrence pattern of patients with different N2 sub-stages. The OS and DFS of N2a1 were not sufficiently distinguished from N1 at multiple stations (N1b). The OS and DFS of N2a2 were intermediate between those of N2a1 and N2b. Current evidence did not support the further subdivision of the N2b. The main recurrence pattern of N2a1, N2a2 and N2b were distant metastasis, and the risks of distant metastasis increased successively. N2a1 patients were at low risk of locoregional recurrence, which could not be reduced by postoperative radiotherapy (PORT). N2a2 and N2b patients had a similar higher risk of locoregional recurrence, which could be reduced to a similar level of N2a1 patients by PORT.
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The Impact of Skip vs. Non-Skip N2 Lymph Node Metastasis on the Prognosis of Non-Small-Cell Lung Cancer: A Systematic Review and Meta-Analysis

Objective: The skip N2 metastases were frequent in non-small-cell lung cancer (NSCLC) and the better prognosis of NSCLC with a skip over non-skip N2 lymph node metastases is controversial. The primary aim of this study is to investigate the prognosis effect of skip N2 lymph node metastases on the survival of NSCLC.

Setting: A literature search was conducted in PubMed, EMBASE, and Cochrane Library with the term of “N2” or “mediastinal lymph node” or “mediastinal nodal metastases”, and “lung cancer” and “skip” or “skipping” in the title/abstract field. The primary outcomes of interests are 3- and 5-year survival in NSCLC.

Participants: Patients who underwent complete resection by lobectomy, bilobectomy, or pneumonectomy with systemic ipsilateral lymphadenectomy and were staged as pathologically N2 were included.

Primary and Secondary Outcome Measures: The 3- and 5-year survival of NSCLC was analyzed. The impact of publication year, number of patients, baseline mean age, gender, histology, adjuvant therapy, number of skip N2 stations, and survival analysis methods on the primary outcome were also analyzed.

Results: A total of 21 of 409 studies with 6,806 patients met the inclusion criteria and were finally included for the analysis. The skip N2 lymph node metastases NSCLC had a significantly better overall survival (OS) than the non-skip N2 NSCLC [hazard ratio (HR), 0.71; 95% CI, 0.62–0.82; P < 0.001; I² = 40.4%]. The skip N2 lymph node metastases NSCLC had significantly higher 3- and 5-year survival rates than the non-skip N2 lymph node metastases NSCLC (OR, 0.75; 95% CI, 0.66–0.84; P < 0.001; I² = 60%; and OR, 0.78; 95% CI, 0.71–0.86; P < 0.001; I² = 67.1%, respectively).

Conclusion: This meta-analysis suggests that the prognosis of skip N2 lymph node metastases NSCLC is better than that of a non-skip N2 lymph node.

The importance of anatomical localization of non-small cell lung carcinoma in predicting mediastinal lymph node metastasis

Bronchopulmonary segmental location of non-small lung carcinomas is closely related to metastatic lymph node foci in the mediastinum. Our aim was to investigate the relationship between the anatomical locations of pulmonary masses on the bronchopulmonary segmental base and metastatic lymph node regions in non-small cell lung cancer using preoperative 18F-FDG PET/CT images. Ninety patients newly diagnosed with non-small cell lung carcinoma and referred to PET/CT imaging for staging were included in the study. Tumoral masses that could be evaluated visually and mediastinal node metastases were identified in 18F-FDG PET/CT images, then the relationship between them was investigated statistically. The diagnostic power of 18F-FDG PET/CT of mediastinal nodes was also revealed. Seventy-four males (82.2%) and sixteen females (17.8%) were enrolled in the study. Half of the patients were diagnosed as adenocarcinoma (50%). Investigation of the tumor location and mediastinal metastatic nodes revealed a statistically significant relationship between the apicoposterior segment of the left superior lobe and the left upper and lower paratracheal, subaortic, paraaortic, and left hilar regions according to the IASLC map. The sensitivity, specificity and accuracy of 18F-FDG PET/CT in the mediastinal nodes were 69.2%, 66.6%, and 68%, respectively. There was no statistically significant relationship between tumor location and 8th TNM Stage. Anatomical locations of non-small cell lung carcinomas can affect the disease stage and prognosis because of their tendency to metastasize to some mediastinal regions. However, this relationship needs to be investigated in larger study groups.

Spanish Lung Cancer Group SCAT trial: surgical audit to lymph node assessment based on IASLC recommendations

Background

The Spanish Customized Adjuvant Therapy (SCAT) trial assessed the role of individualized adjuvant therapy in clinical N0 incidental pN1 and/or N2 non-small cell lung cancer (NSCLC) completely resected. We assessed surgical topics with an in-depth analysis of quality of lymphadenectomy based on International Association for the Study of Lung Cancer (IASLC) recommendations.

Methods

Patients with information about lymphadenectomy available were included (N=451). Prospectively collected data about tumor, type of resection, and postoperative morbidity and quality of lymph node dissection (LND) were retrospectively evaluated. Role of lymph node assessment on survival was analyzed using Kaplan-Meier curves, using regression models to identify prognostic factors.

Results

In 33.7%, 17.7% and 49.9% of cases, regions 7, 10 and 11 respectively were not assessed. In 21.1% of patients, less than three lymph node regions were biopsied, while in 19.6% of patients less than six lymph nodes were assessed. In 53,4% of patients only one N1 region was evaluated. From patients with positive N2, 8.9% had no N1 regions biopsied. Twenty-nine percent of patients with at least one N2 lymph node resected shown the highest region involved. Thirty-day postoperative mortality was unknown. Five-year overall survival (OS) was 61.7% (95% CI: 55.4-67.4%), 51.5% (95% CI: 39.2-62.4%) and 42.3% (95% CI: 32.1-52.2%) for patients with N1, N2 and N1+N2 disease, respectively (P<0.01). Both number of lymph nodes resected and number of lymph nodes involved by tumor were significantly related to prognosis.

Conclusions

IASLC recommendations for surgical resections were not followed in a high proportion of surgical procedures. Hilar and mediastinal lymph node assessment and involvement showed to impact prognosis. Surgical issues such as postoperative mortality could not be evaluated owing to trial design.

The Significance of Skip Mediastinal Lymph Node Metastasis in the Prognosis of Patients with Resected Non-Small-Cell Lung Carcinoma: Is It Really a Better N2 Disease Subtype?

Objective: In this study, we aimed to reveal the prognostic differences between skip and non-skip metastasis mediastinal lymph node (MLN) metastasis.

Methods: A total of 202 patients (179 males and 23 females; mean age, 59.66 ± 9.89 years; range: 29–84 years) who had ipsilateral single-station MLN metastasis were analyzed in two groups retrospectively between January 2009 and December 2017: “skip ipsilateral MLN metastasis” group (sN2) (n = 55,27.3%) [N1(–), N2(+)], “non-skip ipsilateral MLN metastasis” group (nsN2) (n = 147,72.7%) [N1(+), N2(+)].

Results: The mean follow-up was 42.63 ± 34.91 months (range: 2–117 months). Among all patients, and in the sN2 and nsN2 groups, the median overall survival times were 63.5 ± 4.56, 68.8 ± 7, and 59.3 ± 5.35 months, respectively, and the 5-year overall survival rates were 38.2%, 46.3%, and 36.4%.

Conclusion: Skip metastasis did not take its rightful place in TNM classification; thus, further studies will be performed. To detect micrometastasis, future studies on skip metastasis should examine non-metastatic hilar lymph nodes (LNs) through staining methods so that heterogeneity in patient groups can be avoided, that is, to ensure that only true skip metastasis cases are included. Afterwards, more accurate and elucidative studies on skip metastasis can be achieved to propound its prognostic importance in the group of N2 disease.

Survival Analysis in Single N2 Station Lung Adenocarcinoma: The Prognostic Role of Involved Lymph Nodes and Adjuvant Therapy

BACKGROUND

Prognostic factors in patients with single mediastinal station (sN2) involvement continues to be a debated issue.

METHODS

Data on 213 adenocarcinoma patients with sN2 involvement and who had undergone complete anatomical lung resection and lymphadenectomy, were retrospectively reviewed. Clinical and pathological characteristics together with adjuvant therapy (AD) and node (N) status classifications (number of resected nodes (#RN), number of metastatic nodes (#MN), and node ratio (#MN/#RN = NR) were analyzed.

RESULTS

Univariable analysis confirmed that age (0.009), #MN (0.009), NR (0.003), #N1 involved stations (p = 0.003), and skip metastases (p = 0.005) were related to overall survival (OS). Multivariable analysis confirmed, as independent prognostic factors, age <66 years and NR with a three-year OS (3YOS) of 78.7% in NR < 10% vs. 46.6% in NR > 10%. In skip metastases, NR (HR 2.734, 95% CI 1.417-5.277, p = 0.003) and pT stage (HR2.136, 95% CI 1.001-4.557, p = 0.050) were confirmed as independent prognostic factors. AD did not influence the OS of patients with singular positive lymph nodes (p = 0.41), while in patients with multiple lymph nodes and AD, a significantly better 3YOS was demonstrated, i.e., 49.1% vs. 30% (p = 0.004). In patients with N2 + N1 involvement, age (p = 0.002) and AD (p = 0.022) were favorable prognostic factors.

CONCLUSIONS

Adenocarcinoma patients with single N2 station involvement had a favorable outcome in the case of skip metastases and low NR. Adjuvant therapy improves survival with multiple nodal involvement, while its role in single node involvement should be clarified.

Prognostic Value of the Hemoglobin/Red Cell Distribution Width Ratio in Resected Lung Adenocarcinoma

BACKGROUND

The ratio of hemoglobin to red cell distribution width (HRR) has been described as an effective prognostic factor in several types of cancer. The aim of this study was to investigate the prognostic role of preoperative HRR in resected-lung-adenocarcinoma patients.

METHODS

We enrolled 342 consecutive patients. Age, sex, surgical resection, adjuvant treatments, pathological stage, preoperative hemoglobin, red cell distribution width, and their ratio were recorded for each patient.

RESULTS

Mean age was 66 years (SD: 9.0). There were 163 females (47.1%); 169 patients (49.4%) had tumors at stage I, 71 (20.8%) at stage II, and 102 (29.8%) at stage III. In total, 318 patients (93.0%) underwent lobectomy, and 24 (7.0%) pneumonectomy. Disease-free survival multivariable analysis disclosed an increased hazard ratio (HR) of relapse for preoperative HRR lower than 1.01 (HR = 2.20, 95%CI: (1.30-3.72), p = 0.004), as well as for N1 single-node (HR = 2.55, 95%CI: (1.33-4.90), p = 0.005) and multiple-level lymph node involvement compared to N0 for both N1 (HR = 9.16, 95%CI:(3.65-23.0), p < 0.001) and N2 (HR = 10.5, 95%CI:(3.44-32.2, p < 0.001).

CONCLUSION

Pre-operative HRR is an effective prognostic factor of disease-free survival in resected-lung-adenocarcinoma patients, together with the level of pathologic node involvement.

Prognostic factors for survival in patients with completely resected pN2 non-small-cell lung cancer

BACKGROUND

This study examined the incidence of pathologic N2 (pN2) non-small-cell lung cancer (NSCLC) and prognostic factors affecting survival of these patients.

METHODS

A total of 119 patients who underwent surgery for NSCLC (lobectomy and pneumonectomy) between January 2008 and December 2016 were evaluated retrospectively. The patients with pN2 included in this study were assessed in two groups; single pN2 and multiple pN2.

RESULTS

The most common type of resection was lobectomy (56.3%). Ninety-four patients (79%) received adjuvant therapy. Eighty-six patients (72.3%) had single-station pN2 and 33 (27.7%) had multiple pN2. The 5-year survival rates were 29.3% overall, 38.6% in single-station pN2, and 11% in multiple-station pN2 (hazard ratio [HR]: 0.581, p = .037). There was no statistically significant difference in 5-year survival rates between patients with pN1N2 and those with pN0N2 involvement (39.1% vs. 37.1%) (p = .625). Not receiving adjuvant therapy was associated with poor survival prognosis (HR: 8.2 p < .001). The 5-year survival rate was 36.2% among patients with pN2 involvement with 2 or more positive lymph nodes and 19.5% among those with fewer than 2 positive lymph nodes (HR: 0.83, p = .463).

CONCLUSIONS

The most significant prognostic factors associated with survival were pN2 status. Non-skip metastases (pN1N2) and positive lymph node count were not associated with prognosis.

Postoperative long-term survival of non-small cell lung cancer patients with skip-N2 metastases

OBJECTIVE

Radical lymphadenectomy is crucial in operations for non-small cell lung cancer (NSCLC). Usually pN1 and pN2 lymph nodes are affected consecutively (N1N2). Nevertheless, pN2 metastases may also occur in the absence of pN1 as skip-N2 metastases (N0N2). Here we compare the long-term survival of N1N2- and N0N2 patients.

MATERIALS AND METHODS

464 patients underwent surgery for NSCLC at our institution between 2012 and 2017. We retrospectively reviewed data of pN2 stage patients (n = 68). Patients with N1N2 (n = 39) were compared to N0N2 (n = 29) patients. 1-, 3-and 5-year survival rates were measured. Survival was assessed by Kaplan-Meier curves and the cox proportional hazards model was used to identify prognostic factors for overall survival. All patients received adjuvant chemoradiation therapy according to European guidelines.

RESULTS

The baseline characteristics did not differ between groups. We observed no differences in the histology, localization, or gender in our cohort. N0N2 patients showed significantly better 1- (N1N2: 82.4% vs. N0N2 100%; p = 0.001), 3- (14.7% vs. 63.6%; p=<0.001) and 5-year (9.4% vs. 43.8%; p = 0.001) survival rates. Tumor size (Hazard ratio (HR) 1.46, Confidence interval (CI 95%) 1.03-2.04; p = 0.03) and the occurrence of N1N2 (HR 4.26, CI 2.04-8.91; p < 0.0001) were independent prognostic factors for worse long-term survival. The Kaplan-Meier curves showed a reduced overall survival for N1N2 patients (log-rank N1N2, N0N2 p < 0.0001).

CONCLUSION

N1N2 patients have a significantly worse prognosis compared to N0N2 patients. This will aid to classify the heterogeneous pN2-NSCLC patient population more precisely. Further, multimodal therapy should be considered for N1N2 patients.

Metastatic Patterns of Mediastinal Lymph Nodes in Small-Size Non-small Cell Lung Cancer (T1b)

Background: Lymph node metastasis (LNM) status is critical to the treatment. Fewer studies has focused on LNM in patients with small-size non-small cell lung cancer (NSCLC). This study aims to investigate clinicopathological characteristics associated with skip N2 (SN2) and non-skip N2 (NSN2) metastasis, and their metastatic patterns in NSCLC with tumor size of 1–2 cm.

Methods: We reviewed the records of NSCLC patients with tumor size of 1–2 cm who underwent lobectomy with systematic lymph node dissection (LND) between January 2013 and June 2019. Clinical, radiographical, and pathological characteristics were compared among N1, SN2, and NSN2 groups. Metastatic patterns of mediastinal lymph node were analyzed based on final pathology.

Results: A total of 63 NSCLC patients with tumor size of 1–2 cm were staged as pN2, including 25 (39.7%) SN2 and 38 (60.3%) NSN2. The incidence rates of SN2 and NSN2 were 2.8% (25/884) and 4.3% (38/884), respectively. For all clinicopathological characteristics, no significant difference was observed among the groups of N1, SN2, and NSN2. For the tumor located in each lobe, specific nodal drainage stations were identified: 2R/4R for right upper lobe; 2R/4R and subcarinal node (#7) for right middle lobe and right lower lobe; 4L and subaortic node (#5) for left upper lobe; #7 for left lower lobe. However, there were still a few patients (10.9%, 5/46) had the involvement of lower zone for tumors of upper lobe and the involvement of upper zone for lower lobe.

Conclusions: SN2 occurs frequently in patients with small-size NSCLC. Whether lobe-specific selective LND is suitable for all small-size patients deserves more studies to confirm. Surgeons should be more careful when performing selective LND for tumors located in the lower and upper lobes.

Nodal Involvement Pattern in Clinical Stage IA Non-Small Cell Lung Cancer According to Tumor Location

PURPOSE

The purpose of this study was to investigate lymph node involvement pattern in clinical stage IA non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

Clinical stage ⅠA NSCLC patients who underwent lobectomy and lymph node resection were included in this retrospective study. Mediastinal lymph node involvement was distinguished by different lobes and tumor size.

RESULTS

From 2000 to 2015, a total of 759 patients were identified: 282 (37.2%) with tumors in the right upper lobe (RUL), 183 (24.1%) in the left upper lobe (LUL), 124 (16.3%) in the right lower lobe (RLL), 103 (13.6%) in the left lower lobe (LLL), and 67 (8.8%) in the right middle lobe (RML). Patients with tumor size ≤1 cm accounted for 19.6%, >1 and ≤2 cm for 47.8%, >2 and ≤3 cm for 32.5%. Patients with pN1 accounted for 8.2%, and pN2 for 12.5%. Among patients with pN2, the inferior mediastinum was involved in 9.7% of RULs and 17.4% of LULs; the superior mediastinum was involved in 52.2% of RLLs and 36.4% of LLLs. Mediastinal lymph node metastasis was found in 13.2% of patients with size >1 and ≤2 cm, and 19.0% of >2 and ≤3 cm. Patients with tumors ≤1 cm had no N2 lymph node involved.

CONCLUSION

Selective lymph node dissection based on tumor location is not recommended in clinical stage ⅠA NSCLC, and systemic lymph node dissection should be performed for NSCLC with size >1 cm.

[Prognostic Factors of N2 Stage Non-small Cell Lung Cancer after Surgery]

背景与目的

N2期非小细胞肺癌患者预后异质性很强，本研究旨在探索其预后相关因素。

方法

纳入四川大学华西医院胸外科2007年1月-2016年12月间行根治性切除的N2期患者，使用Cox模型比较临床病理学特征与总体生存率之间的关系，使用Kaplan-Meier法绘制生存曲线，并且根据淋巴结转移情况进行亚组分析。

结果

总共纳入773例N2期患者，中位随访时间57.2个月，5年总体生存率为34.8%。肿瘤原发灶-淋巴结-远处转移（tumor-node-metastasis, TNM）分期、多站淋巴结转移、跳跃性转移、脉管侵犯、辅助化疗为预后相关的独立风险因素。T1-3期患者具有相似的预后，T4期患者预后明显更差。单站跳跃性转移的患者预后最好，5年生存率达48.9%。

结论

N2患者中T4期预后差。在将来的分期中应结合淋巴结转移站数和跳跃性转移进行更精细的N分期划分。

Skip N2 Metastasis in Pulmonary Adenocarcinoma: Good Prognosis Similar to N1 Disease

INTRODUCTION

The prognostic effect and mechanism of skip N2 lung cancer remain unclear. Our study aimed to elucidate the influence of skip N2 on overall survival (OS) and disease-free survival (DFS) compared with N1 and non-skip N2 in patients with lung adenocarcinoma.

PATIENTS AND METHODS

Patients with lung adenocarcinoma and lymph node involvement between May 2011 and December 2015 were retrospectively analyzed. The outcomes of skip N2 patients were compared with N1 and non-skip N2 patients. Prognosis was further investigated according to the N status in different adenocarcinoma subtypes. Univariate and multivariate analyses were carried out to define independent risk factors for OS and DFS.

RESULTS

A total of 456 patients with lung adenocarcinoma, 169 with N1 disease, 81 with skip N2 disease, and 206 with non-skip N2 disease, were enrolled in this study. All tumors were invasive adenocarcinoma, and the predominant subtypes were acinar in 252, papillary in 42, solid in 119, micropapillary in 20, and invasive mucinous adenocarcinoma in 23 patients. The DFS and OS of N1 and skip N2 diseases were similar and significantly better than those of patients with non-skip N2 disease. The prognosis according to lymph node status was significantly different in acinar-predominant subtypes in terms of both OS and DFS.

CONCLUSIONS

Skip N2 disease has a similar prognosis to N1 disease and is significantly better than that of non-skip N2 disease in relation to OS and DFS. Skip N2 has a prognostic advantage in patients with the acinar-predominant subtype.