Blind spot in lung cancer lymph node metastasis: Cross‐lobe peripheral lymph node metastasis in early stage patients

Abstract

BackgroundAt present, it has not yet been determined whether metastasis can be transferred cross‐lobe to peripheral lymph nodes (LNs) from other lobes in early stages of lung cancer, especially without any direct involvement to the pleura and parenchyma of the lobe. This study was conducted to investigate this issue.MethodsA retrospective analysis was conducted at the Chinese Academy of Medical Sciences. Patients undergoing right middle and lower lobectomy with lymphadenectomy for preoperative clinical stage Ia–IIIa from 2014 to 2015 were identified. To avoid interference, cases were limited to tumors within the primary lobe. When a tumor is completely located in the lower lobe, no direct invasion occurs into the visceral pleura/bronchus/parenchyma of the middle lobe and tumor cell metastasis into the peripheral LNs (stations 12–14) in the middle lobe is defined as cross‐lobe lymph node metastasis (CLM).ResultsA total of 68 patients were identified, of which nine (13.2%) had CLM. Seven had squamous cell carcinoma, one adenocarcinoma, and one small cell carcinoma. Seven cases (77.8%) had intermediate bronchus invasion, and seven cases (77.8%) intermediate bronchus adjacent lymph node involvement (station 11). Compared to non‐CLM patients, tumor diameter (5.2 vs. 3.2; P = 0.28), N2 lymph node metastasis rate (66.7% vs. 28.8%; P = 0.03), late stage (IIIa 77.8% vs. 35.6%; P = 0.04), and invasion of intermediate bronchus (77.8% vs. 45.8%; P = 0.07) relatively increased.ConclusionNon‐primary lobe peripheral LN metastasis exists in lung cancer and requires greater attention and further study.

Risk factors of lobar lymph node metastases in non-primary tumor-bearing lobes among the patients of non-small-cell lung cancer

“…This study retrospectively investigated the prevalence and risk factors of lobar lymph node metastasis from NTBL in patients with NSCLC. In our study, NTBL lobar lymph nodes were involved in 12.6% of patients, which is consistent with the published results, ranging from 6.5 to 13.2% [ 11 , 14 , 15 , 21 ]. A higher proportion of adenocarcinomas were observed in the positive NTBL group compared to the negative NTBL group.…”

“…Given the retrospective design, some selection bias could not be avoided: the percentage of metastatic N1 and N2 patients was more than that of other studies [ 11 , 14 ]; this retrospective study was carried out in a single center with a limited number of enrolled patients. But the rate of aberrant lymph node metastases to NTBL was 12.6% (38 out of 301 patients), which is consistent with the published results, ranging from 6.5% to 13.2% [ 11 , 14 , 15 , 21 ]. Besides, there is no significant difference between 301 enrolled patients with the excluded 40 patients who performed extended NTBL lymph node dissection but missed pathology diagnosis, in terms of demographic information such as sex and age ( S5 Table ).…”

“…This rate is higher than two previously reported studies: 6.5% by Yamanaka and colleagues [ 14 ] and 9.2% by Sato and colleagues [ 11 ]. But it is similar as the rate reported by Li and colleagues at 13.2% [ 15 ], and 12.7% [ 21 ]. These rates of anomalous lymph node metastases, which have received little investigation previously, suggest that extended lymphadenectomy including the lobar lymph nodes of NTBL should be considered to improve the accuracy of staging, and decrease locoregional recurrence.…”

“…All these findings imply that either aberrant lymphatic flow to the lobar lymph nodes of NTBL is preserved or it is secondary to overburdened lymph node involvement in certain patients with NSCLC. However, the lobar lymph nodes of NTBL are not included among those routinely resected according to the European Society of Thoracic Surgeons (ESTS) guidelines [ 13 ] and there have been only few reports [ 14 , 15 ] on the prevalence and clinical features of lobar lymph node metastases of NTBL.…”

Lymph node metastasis outside of a tumor-bearing lobe in primary lung cancer and the status of interlobar fissures

“…The present study found that 15 (12.7%) patients had lymph node metastases in NTBL and 9 had metastases in N2 sites. As reported in the literature, [24] whether or not LN metastases occurred in NTBL did not affect staging or treatment. We demonstrated a significantly higher frequency of lymph node metastases in NTBL among tumors invading across complete fissures and in tumors sized 3.0 cm or more in diameter.…”