Clinical Prognosis of Superior Versus Basal Segment Stage I Non-Small Cell Lung Cancer

Risk Factors for Locoregional Relapse After Segmentectomy: Supplementary Analysis of the JCOG0802/WJOG4607L Trial

INTRODUCTION

The JCOG0802/WJOG4607L trial revealed superior overall survival in segmentectomy compared with lobectomy for small-peripheral NSCLC. Nevertheless, locoregional relapse (LR) is a major issue for segmentectomy. An ad hoc supplementary analysis aimed to determine the risk factors for LR and the degree of advantages of segmentectomy on the basis of primary tumor sites.

METHODS

Participants in multi-institutional and intergroup, open-label, phase 3 randomized controlled trial in Japan were enrolled from August 10, 2009, to October 21, 2014. Risk factors for LR after segmentectomy and clinical features following the primary tumor site were investigated.

RESULTS

Of 1105 patients, 576 and 529 underwent lobectomy and segmentectomy, respectively. The primary tumor site for segmentectomy was the left upper division, left lingular segment, left S6, left basal segment, right upper lobe, right S6, or right basal segment. Multivariable analysis in the segmentectomy group revealed that pure-solid appearance on thin-section computed tomography (OR = 3.230; 95% confidence interval [CI]: 1.559-6.690; p = 0.0016), margin distance less than the tumor size (OR = 2.682; 95% CI: 1.350-5.331; p = 0.0049), and male sex (OR = 2.089; 95% CI: 1.047-4.169; p = 0.0366) were significantly associated with LR. Patients with left lingular segment tumors (OR = 4.815; 95% CI: 1.580-14.672) tended to experience LR more frequently than those with left upper division tumors, although primary tumor sites were not statistically significant.

CONCLUSIONS

Thin-section computed tomography findings and margin distance are important factors to avoid LR in segmentectomy.

Metastatic pathways to the lower zone by segment in patients with clinical T1 lower lobe non-small cell lung cancer

OBJECTIVE

Segmentectomy and mediastinal lymph node dissection (LND) may increasingly be used for non-small cell lung cancer (NSCLC). Lymph node metastasis (LNM) distribution varies by lower lobe segments; however, its segment-specific spread to the lower zone (#8, 9) (LZ) in lower lobe NSCLC is seldom reported.

METHODS

In total, 352 patients with clinical T1 lower lobe NSCLC who underwent lobectomy with systematic or lobe-specific LND were included for analysis between January 2006 and December 2018.

RESULTS

Fifty-eight (16.2%) patients had LNM (pN1: 24, pN2: 34), and nine (2.6%) had LZ metastasis. LZ metastasis was significantly more frequent in tumors with diameter > 2 cm, tumors without ground-glass opacity on radiological findings, left lung cancer, and basal segment lung cancer (respectively, p = 0.039, 0.006, 0.0177, 0.0024). None of the S6 NSCLC patients had LZ metastasis. Two patients with right basal segment NSCLC had LZ metastases (tumor on S10) as well as N1 lymph node and subcarinal zone metastasis. Seven (8.4%) patients with left basal segment NSCLC had LZ metastasis (tumor on S8: 3, tumor on S10: 4). Of them, three patients with left basal NSCLC had isolated LZ metastasis.

CONCLUSIONS

The LND of the LZ can be omitted for clinical T1 patients with S6 NSCLC. In addition, the LND of the LZ may be omitted in right basal NSCLC if intraoperative confirmation of negative N1 and subcarinal zone lymph nodes is obtained; however, it is necessary for left basal segment NSCLC.

Lymph node dissection in small peripheral lung cancer: Supplemental analysis of JCOG0802/WJOG4607L

OBJECTIVE

The optimal region of lymph node dissection (LND) during segmentectomy in patients with small peripheral non-small cell lung cancer requires clarification. Through a supplemental analysis of the Japan Clinical Oncology Group (JCOG) 0802/West Japan Oncology Group (WJOG) 4607L, we investigated the associated factors, distribution, and recurrence pattern of lymph node metastases (LNMs) and proposed the optimal LND region.

METHODS

Of the 1106 patients included in the JCOG0802/WJOG4607L, 1056 patients with LNDs were included in this supplemental analysis. We investigated the distribution and recurrence pattern of LNMs along with the radiologic findings (with ground-glass opacity, part-solid tumor; without ground-grass opacity component, pure-solid tumor).

RESULTS

The radiologic findings were the only significant factor for LNMs. Of 533 patients with part-solid tumors, 8 (1.5%) had LNMs. Further, only 3 (0.5%) patients had pN2 disease, and no patients had interlobar LNMs from nonadjacent segments. Of the 523 patients with pure-solid tumors, 55 (10.5%) had LNMs, and 28 (5.4%) had pN2 disease. Five patients had metastases to nonadjacent interlobar lymph nodes (LNs). Two (2.0%) patients with S6 tumors had upper mediastinal LNMs. In addition, the incidence of mediastinal LN recurrence in patients with S6 lung cancer was greater in those who underwent selective LND than those who underwent systematic LND (P = .0455).

CONCLUSIONS

Nonadjacent interlobar and mediastinal LND have little impact on pathologic nodal staging in patients with part-solid tumors. In contrast, selective LND is recommended at least for patients with pure-solid tumors.

Tumor distance from the mediastinum predicts N2 upstaging in clinical stage I lower-lobe non-small cell lung cancer

OBJECTIVE

Pulmonary lymphatic drainage of the lower lobe into the mediastinal lymph nodes includes not only the pathway via the hilar lymph nodes but also the pathway directly into the mediastinum via the pulmonary ligament. This study aimed to determine the association between the distance from the mediastinum to the tumor and the frequency of occult mediastinal nodal metastasis (OMNM) in patients with clinical stage I lower-lobe non-small cell lung cancer (NSCLC).

METHODS

Between April 2007 and March 2022, data of patients who underwent anatomical pulmonary resection and mediastinal lymph node dissection for clinical stage I radiological pure-solid lower-lobe NSCLC were retrospectively reviewed. In computed tomography axial sections, the ratio of the distance from the inner edge of the lung to the inner margin of the tumor within the lung width of the affected lung was defined as the inner margin ratio. Patients were divided into 2 groups based on whether the inner margin ratio was ≤0.50 (inner-type) or >0.50 (outer-type), and the association between inner margin ratio status and clinicopathological findings was assessed.

RESULTS

In total, 200 patients were enrolled in the study. OMNM frequency was 8.5%. More inner-type than outer-type patients had OMNM (13.2% vs 3.2%; P = .012) and skip N2 metastasis (7.5% vs 1.1%; P = .038). Multivariable analysis revealed that the inner margin ratio was the only independent preoperative predictor of OMNM (odds ratio, 4.72; 95% CI, 1.31-17.07; P = .018).

CONCLUSIONS

Tumor distance from the mediastinum was the most important preoperative predictor of OMNM in patients with lower-lobe NSCLC.

Assessment of lymph node metastasis of ≤20 mm non-small cell lung cancer originating from superior segment compared to basal segment

BACKGROUND

Segmentectomy with curative intention is occasionally performed for early non-small cell lung cancer (NSCLC). However, a major problem has been pointed out, in that the rate of locoregional recurrence is higher after segmentectomy than after lobectomy. This study aimed to investigate differences in rates of lymph node metastasis between segment 6 and basal segment NSCLC as potential candidates for segmentectomy and to explore factors associated with locoregional recurrence of segmentectomy.

METHODS

We retrospectively analyzed 461 patients with lower lobe NSCLC who underwent segmentectomy or lobectomy with mediastinal lymph node dissection between 2011 and 2021. Among these, 122 patients with clinical N0 NSCLC, diameter ≤ 20 mm, and consolidation tumor ratio >0.5 were analyzed.

RESULTS

The 122 patients were divided into a segment 6 group (n = 51) and a basal segment group (n = 71). Frequency of lymph node metastasis was significantly higher in the segment 6 group (17.7%) than in the basal segment group (4.2%; p = 0.01). Metastases to lymph node station 7 were seen in five of 122 patients (4.1%). Hilar lymph node metastasis occurred in nine of 122 patients (7.4%). Notably, metastases to station 11, 11i and 11 s lymph nodes were the most frequent patterns for hilar lymph nodes (41.7%).

CONCLUSIONS

Station 11 lymph nodes are adjacent to the remaining lung segment or pulmonary artery in S6 segmentectomy or basal segmentectomy. Part of the NSCLC in segment 6 patients may thus be considered for lobectomy owing to the difficulty of complete dissection of station 11 lymph nodes.

Do tumours located in basal segments have better survival than superior segments in lung cancer?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was in patients with lower lobe lung cancer undergone pulmonary resection, are the tumours located in superior segments superior to the tumours in basal segments in terms of survival? We concluded that there were no statistically significant differences in survival and recurrence between superior and basal segments for lung cancer patients, but overall survival and relapse-free survival were worse in superior segment for clinical stage I non-small cell lung cancer (NSCLC) in the right lower lobe, and remained unclear about other stages of lung cancer. In consideration of operation procedure, we speculate that the superior segments had a relatively worse survival in patients with early-stage NSCLC who underwent segmentectomy; likewise, in patients underwent at least lobectomy, survival of the superior segments was not better than that of the basal segments.

Survival rates of patients with tumors originating in different segments of the left upper lung in stage I to III non-small cell lung cancer

Background

The aim of this research was to evaluate the effect of spatial location of tumors on the prognosis of patients with left upper lung non-small cell lung cancer (NSCLC), with a focus on the S1+2+3 and lingual segment.

Methods

A total of 486 patients who underwent lobectomy and systematic lymph node dissection were collected retrospectively in this study (354 S1+2+3 and 132 lingual segment patients). Factors impacting survival were assessed via univariate analyses, multivariate analyses, and log-rank tests.

Results

Compared with tumor location in S1+2+3, lingual segment tumor location of stage II to III left upper lung NSCLC patients was significantly associated with a better 5-year disease-free survival (DFS) (P=0.041). Multivariate analysis results showed that tumor location in the lingual segment was a good independent prognostic factor of stage II to III left upper lung NSCLC patients [hazard ratio (HR) =0.602, 95% confidence interval (CI): 0.149-0.865, P=0.006). However, in stage I left upper lung NSCLC, tumor location (HR =1.069, 95% CI: 0.571-2.000, P=0.835) was not an independent prognostic factor, and only T2 (HR =2.422, 95% CI: 1.271-4.620, P=0.007) was an independent worse prognosis factor.

Conclusions

Tumor location in the lingual segment of left upper lung stage II to stage III NSCLC is a good independent prognostic factor compared with S1+2+3. Nevertheless, tumor location does not impact the prognosis of patients with stage I NSCLC in the left upper lung.

Complex segmentectomy in the treatment of stage IA non-small-cell lung cancer

OBJECTIVES

Although segmentectomy for lung cancer has been widely accepted, complex segmentectomy, which creates several, intricate intersegmental planes, remains controversial. Potential arguments include risk of incurability and 'failure of cancer control'. We compared the outcomes of complex segmentectomy versus lobectomy and evaluated its use in lung cancer treatment.

METHODS

We retrospectively reviewed clinical stage IA lung cancer patients who underwent complex segmentectomy (n = 99) or location-adjusted lobectomy (n = 94) between April 2009 and December 2017. Clinicopathological and postoperative results were compared. Factors affecting survival were assessed by the Kaplan-Meier method and the Cox regression analysis.

RESULTS

No significant differences were detected in 30-day mortality (0% vs 0%), overall complications (26.3% vs 21.3%) and prolonged air leakage (11.1% vs 9.6%) rates between the 2 groups, respectively. Comparable results were obtained for 5-year overall (93.5% vs 96.4%, respectively; P = 0.21) or recurrence-free (92.3% vs 88.5%, respectively; P = 0.82) survivals after complex segmentectomy or lobectomy. There were 2 (2.0%) recurrences after complex segmentectomy and 7 (7.5%) after lobectomy (P = 0.094), with 0 (0%) margin relapses in each group. Multivariable Cox regression analysis revealed that complex segmentectomy and lobectomy had a numerically similar impact on recurrence-free survival (hazard ratio 0.93, 95% confidence interval 0.32-2.69; P = 0.90).

CONCLUSIONS

Complex segmentectomy can provide acceptable short- and long-term outcomes in lung cancer treatment.

[Progress in Survival Prognosis of Segmentectomy for Early-stage Non-small Cell Lung Cancer]

Surgery is currently the most appropriate treatment for early-stage non-small cell lung cancer (NSCLC). Increasing unilateral or bilateral multiple primary lung cancer being found, segmentectomy has attracted wide attention for its unique advantages in the treatment for such tumors. Ground glass opacity dominant early-stage NSCLC is associated with a good prognosis and can be cured by segmentectomy, however, the treatment of solid-dominant NSCLC remains controversial owing to the invasive nature. With the in-depth study on the lymph node metastasis pathway, radiological characteristics and molecular biology of NSCLC, a large part of solid nodules with certain characteristics can also be cured by segmentectomy. This paper reviews the research status and progress about the indication of segmentectomy.
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Intentional Segmentectomy for Clinical T1 N0 Non-small Cell Lung Cancer: Survival Differs by Segment

BACKGROUND

Outcomes after segmentectomy compare favorably with those after lobectomy in patients with stage I non-small cell lung cancer (NSCLC). Whether long-term outcomes vary by segmentectomy location is unclear. We investigated whether disease-free survival (DFS) and overall survival (OS) differ by segmentectomy location after intentional segmentectomy for clinical T1 N0 M0 NSCLC.

METHODS

Patients who received intentional segmentectomy for cT1 N0 M0 NSCLC from 2000 to 2018 were reviewed. Patients with prior lung cancer, forced expiratory volume in 1 second of less than 50%, or R1/R2 resection were excluded. Segmentectomy groups were left (L) basilar, L segment 6, L lingula, L trisegment; right (R): basilar (R_Bas), segment 6 (R_S6), and R upper. The 5- and 10-year DFS and OS were estimated using Kaplan-Meier and compared between groups using the log-rank test. Factors associated with DFS and OS were determined using Cox proportional hazards models.

RESULTS

In total, 416 patients met the inclusion criteria. Segmentectomy groups differed with regard to surgical approach, mediastinal lymphadenectomy, lymphovascular invasion, tumor histology, margin distance, and adjuvant therapy. Long-term outcomes were worst after R_S6 resection (5-year DFS, 57.6% [95% confidence interval {CI}, 45.7%-72.7%]; OS, 66.3% [95% CI, 54.7%-80.3%]) and best after R_Bas resection (5-year DFS, 77.1% [95% CI, 59.2%-100%]; OS, 79.5% [95% CI, 60.9%-100%]). On multivariable analysis, R_S6 resection was independently associated with DFS vs R_Bas (hazard ratio, 2.89; 95% CI, 1.18-7.08; P = .02) and OS vs R_Bas (hazard ratio, 4.35; 95% CI, 1.61-11.76; P = .004).

CONCLUSIONS

Resection of R_S6 is independently associated with worse DFS and OS in patients receiving intentional segmentectomy for cT1 N0 M0 NSCLC and may warrant more extensive resection, complete lymph node dissection, and closer postoperative surveillance.

Oncologic Outcomes of Surgery Versus SBRT for Non-Small-Cell Lung Carcinoma: A Systematic Review and Meta-analysis

BACKGROUND

The optimal treatment of stage I non-small-cell lung carcinoma is subject to debate. The aim of this study was to compare overall survival and oncologic outcomes of lobar resection (LR), sublobar resection (SR), and stereotactic body radiotherapy (SBRT).

METHODS

A systematic review and meta-analysis of oncologic outcomes of propensity matched comparative and noncomparative cohort studies was performed. Outcomes of interest were overall survival and disease-free survival. The inverse variance method and the random-effects method for meta-analysis were utilized to assess the pooled estimates.

RESULTS

A total of 100 studies with patients treated for clinical stage I non-small-cell lung carcinoma were included. Long-term overall and disease-free survival after LR was superior over SBRT in all comparisons, and for most comparisons, SR was superior to SBRT. Noncomparative studies showed superior long-term overall and disease-free survival for both LR and SR over SBRT. Although the papers were heterogeneous and of low quality, results remained essentially the same throughout a large number of stratifications and sensitivity analyses.

CONCLUSION

Results of this systematic review and meta-analysis showed that LR has superior outcomes compared to SBRT for cI non-small-cell lung carcinoma. New trials are underway evaluating long-term results of SBRT in potentially operable patients.

Segment Location and Ground Glass Opacity Ratio Reliably Predict Node-Negative Status in Lung Cancer

BACKGROUND

Although selective mediastinal lymph node dissection based on lobe-specific nodal metastasis has been proposed for non-small cell lung cancer, controversy remains over its validity. We hypothesized that different segments within the same lobe might have different patterns of lymph node metastasis.

METHODS

Data on 2749 invasive non-small cell lung cancer patients who underwent pulmonary resection with systematic lymph node dissection from April 2008 to December 2015 were retrospectively analyzed. The segment location and consolidation tumor ratio were identified using preoperative computed tomography scans.

RESULTS

None of the 151 tumors with consolidation tumor ratio ≤ 0.5 had lymph node involvement. None of the 333 tumors located in apical segments had inferior mediastinal lymph node metastasis. When the analysis was limited to patients without hilar nodes involvement, only 7 out of 740 (0.9%) peripheral upper lobe tumors had inferior mediastinal lymph node metastasis. Interestingly, all these 7 tumors showed visceral pleural invasion. If hilar nodes were negative, superior mediastinal lymph node metastasis was not present for lower lobe ground glass opacity lesions. Among patients with left lower lobe tumors, if hilar nodes were negative, station 4L lymph node metastasis was not found in superior-segment or basal-segment tumors, and station 5/6 lymph node involvement was always absent in basal-segment tumors.

CONCLUSIONS

Segment location, ground glass opacity proportion, and absence of hilar lymph nodes involvement are reliable predictors of node-negative status in specific mediastinal regions. Based on these findings, we propose a new selective mediastinal lymph node dissection strategy for non-small cell lung cancer.

Meta-analysis of segmentectomy versus lobectomy for radiologically pure solid or solid-dominant stage IA non-small cell lung cancer

OBJECTIVE

Whether segmentectomy can be used to treat radiologically determined pure solid or solid-dominant lung cancer remains controversial owing to the invasive pathologic characteristics of these tumors despite their small size. This meta-analysis compared the oncologic outcomes after lobectomy and segmentectomy regarding relapse-free survival (RFS) and overall survival (OS) in patients with radiologically determined pure solid or solid-dominant clinical stage IA non-small cell lung cancer (NSCLC).

METHODS

A literature search was performed in the MEDLINE, EMBASE, and Cochrane Central databases for information from the date of database inception to March 2019. Studies were selected according to predefined eligibility criteria. The hazard ratio (HR) and associated 95% confidence interval (CI) were extracted or calculated as the outcome measure for data combining.

RESULTS

Seven eligible studies published between 2014 and 2018 enrolling 1428 patients were included in the current meta-analysis. Compared with lobectomy, segmentectomy had a significant benefit on the RFS of radiologically determined pure solid or solid-dominant clinical stage IA NSCLC patients (combined HR: 1.46; 95% CI, 1.05-2.03; P = 0.024) and there were no significant differences on the OS of these patients (HR: 1.52; 95% CI, 0.95-2.43; P = 0.08).

CONCLUSIONS

Segmentectomy leads to lower survival than lobectomy for clinical stage IA NSCLC patients with radiologically determined pure solid or solid-dominant tumors. Moreover, applying lobectomy to clinical stage IA NSCLC patients with radiologically determined pure solid or solid-dominant tumors (≤2 cm) could lead to an even bigger survival advantage. However, there are some limitations in the present study, and more evidence is needed to support the conclusion.

Prognostic significance of basal versus superior segment in patients with completely resected lung adenocarcinoma in the lower lobe

Background

Although the lower lobes of the lungs occupy half of the chest on both sides, the prognostic value of tumor location in lung cancer in the lower lobe has not been well demonstrated. This study investigated the prognostic value of tumor location (basal vs. superior) in patients with resected lung adenocarcinoma in the lower lobe.

Methods

A total of 207 patients undergoing lobectomy for lung adenocarcinoma in the lower lobe were included in the study. The association between tumor location and mediastinal lymph node metastasis was analyzed. Prognostic factors of overall survival and probability of freedom from recurrence (FFR) were also investigated.

Results

During follow‐up, 71 (34.3%) patients developed recurrence. Patients with basal segment tumors had a significantly higher possibility of developing N2 lymph node metastasis than those with superior segment tumors (P = 0.025). Univariate analysis showed that location in the basal (vs. superior) segment was a significant prognostic factor for a lower probability of FFR (P = 0.013). Basal (vs. superior) segment remained a significant prognostic factor for a lower probability of FFR (P = 0.010) in multivariate analysis.

Conclusions

Basal segment tumors have a significantly higher possibility of developing N2 lymph node metastasis than superior segment tumors in resected lung adenocarcinoma in the lower lobe. Tumor location at the basal segment was a significant prognostic factor for a lower probability of FFR. This information is useful for patient stratification of risk of postoperative recurrence.