Prognosis and segment-specific nodal spread of primary lung cancer in the right lower lobe

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.

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.

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.

Complete dissection of right paratracheal lymph nodes (stations 2R and 4R) is critical to improve the prognosis of lung cancer patients: A retrospective cohort study

BACKGROUND

The optimal extent of mediastinal lymph node dissection is still under debate. This study aimed to investigate the prognostic impact of complete dissection of right paratracheal lymph nodes (LNs) in right-sided non-small cell lung cancer (NSCLC) and evaluate the potential patient population who will particularly benefit from right paratracheal node dissection (RPND).

METHODS

Between January 2009 and December 2019, we retrospectively reviewed 2650 patients with primary right-sided NSCLC who underwent pulmonary surgery with lymphadenectomy in the Western China Lung Cancer Database. A total of 2447 patients received both 2R and 4R LNs dissection (complete RPND group), 162 patients received only 2R or 4R LNs dissection (incomplete RPND group), and 41 patients received neither 2R nor 4R LNs dissection (no RPND group). Overall survival (OS) was analyzed.

RESULTS

The metastasis rates in stations 2R and 4R were 6.5% and 8.0%, respectively. In stage N2 patients, the frequency of involvement of stations 2R/4R was 74.8%. The complete RPND group had a significantly better survival than the incomplete and no RPND group (5-year OS, 79.5% vs. 72.7% vs. 65.5%; p < 0.001). In the multivariate analysis, status of RPND (incomplete RPND vs. complete RPND: HR 1.45, 95% CI: 1.10-1.90; p = 0.009; no RPND vs. complete RPND: HR 2.25, 95% CI: 1.37 to 3.69; p = 0.001), age, gender, tumor size, histological type, pTNM stage, pT stage, pN stage, and adjuvant treatment were independent factors for OS.

CONCLUSIONS

Complete RPND brings survival benefits to patients with right-sided NSCLC. We suggest complete RPND as a standard procedure for patients with right-sided NSCLC.

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.

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.

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.

[Advances in Surgical Treatment of Early Stage Non-small Cell Lung Cancer]

肺癌是恶性肿瘤患者首位的死亡原因，随着计算机断层扫描（computed tomography, CT）等影像筛查的普及，肺癌的疾病谱正在发生变化，以往以中央型局部晚期肺鳞癌为主，而目前肺癌疾病谱主要为以孤立性肺结节、磨玻璃结节、亚厘米结节等为影像学表现的早期肺腺癌。早期肺癌是目前临床研究的热点，本文将就早期肺癌外科治疗的多个方面进展进行述评。