Sentinel node mapping in lung cancer: the Japanese experience

Sentinel lymph node detection for lung cancer surgery: a possible pathological surrogate of overall lymph node dissection

Background

Systematic lymph node dissection (SLND) is currently the gold standard for lung cancer surgery. However, this is not the case for breast cancer or melanoma, where sentinel lymph node (SLN) identification is routine. The SLN could be a possible surrogate for the pathological status of the other lymph nodes, but there is limited data in the literature for lung cancer surgery. The main objective of this study was to evaluate pathological concordance between the SLN and the complete lymphadenectomy.

Methods

In this retrospective study, we reviewed all cases of localized lung cancer that had benefited from our SLN identification protocol and underwent surgery (segmentectomy or lobectomy) between December 2020 and December 2023. We examined the pathological status of the SLN and the rest of the lymph node dissection to assess the pathological concordance rate.

Results

After exclusion, 106 patients with localized stage I-IIA non-small cell lung cancer and suspected node negative disease (N0) were included in our study. Of these 106 patients, 96 had a pN0 SLN (90.6%) and 10 had a positive SLN (pN+), resulting in an upstaging rate of 9.4%. All patients with a pN0 SLN were also pN0 for the rest of the lymph node dissection, corresponding to a pathological concordance rate of 100%. Disease-free survival was statistically lower in the pN+ SLN group than in the pN0 SLN group (p<0.0001).

Conclusion

We demonstrated a 100% pathological concordance between SLN when it is cancer-free and the rest of the lymph nodes in the lymph node dissection, suggesting that the SLN is a good indicator of the overall pathological status of the other lymph nodes in the thorax.

Sentinel Lymph Node in Non-Small Cell Lung Cancer: Assessment of Feasibility and Safety by Near-Infrared Fluorescence Imaging and Clinical Consequences

Occult micrometastases can be missed by routine pathological analysis. Mapping of the pulmonary lymphatic system by near-infrared (NIR) fluorescence imaging can identify the first lymph node relay. This sentinel lymph node (SLN) can be analyzed by immunohistochemistry (IHC), which may increase micrometastasis detection and improve staging. This study analyzed the feasibility and safety of identifying SLNs in thoracic surgery by NIR fluorescence imaging in non-small cell lung cancer (NSCLC). This was a prospective, observational, single-center study. Eighty adult patients with suspected localized stage NSCLC (IA1 to IIA) were included between December 2020 and May 2022. All patients received an intraoperative injection of indocyanine green (ICG) directly in the peri tumoural area or by electromagnetic navigational bronchoscopy (ENB). The SLN was then assessed using an infrared fluorescence camera. SLN was identified in 60 patients (75%). Among them, 36 SLNs associated with a primary lung tumor were analyzed by IHC. Four of them were invaded by micrometastases (11.1%). In the case of pN0 SLN, the rest of the lymphadenectomy was cancer free. The identification of SLNs in thoracic surgery by NIR fluorescence imaging seems to be a feasible technique for improving pathological staging.

Extent of Segmentectomy That Achieves Greater Lung Preservation Than Lobectomy

BACKGROUND

This study sought to clarify the extent of segmentectomy that achieves greater lung preservation than lobectomy.

METHODS

This was a single-center retrospective cohort study involving 374 patients with lung cancer who were treated with either lobectomy or segmentectomy between 2013 and 2018. The percentage of preserved pulmonary function (%PPF) after surgery was compared among patients who underwent lobectomy (n = 164), segmentectomy of 2 or more segments (Seg ≥2S; n = 42), and segmentectomy of less than 2 segments (Seg <2S; n = 168). Using perfusion scintigraphy, forced expiratory volume in 1 second of the preserved target lobe was measured to examine its effect on the %PPF. The number of resected subsegments (SSs) in segmentectomy that made the %PPF higher than that observed with lobectomy was also examined.

RESULTS

Mean %PPF was lowest in those patients who underwent lobectomy (86%), followed by Seg ≥2S (89%) and Seg <2S (95%) (P < .001), but the difference between the lobectomy and Seg ≥2S was not significant (P = .21). The forced expiratory volume in 1 second of the preserved target lobe was significantly lower in the Seg ≥2S group than in the Seg <2S group (P < .001). The number of resected SSs was 6 to 12 in lobectomy, 4 to 7 in Seg ≥2S, and 1 to 4 in Seg <2S. Although the %PPF after segmentectomy of less than 5 SSs (Seg <5SS) was significantly higher than that after lobectomy (P < .001), the %PPF after segmentectomy of 5 or more SSs (Seg ≥5SS) was not significantly different from that after lobectomy (P = .68).

CONCLUSIONS

Both the Seg ≥2S and Seg ≥5SS groups did not differ from lobectomy in %PPF because of the low function of preserved target lobe.

Lymphoscintigraphy in early-stage non-small cell lung cancer with technetium-99m nanocolloids and hybrid SPECT/CT: a pilot project

OBJECTIVE

The goal of our study was to determine if lymph node activity could be visualized using a hybrid single-photon emission computed tomography/computed tomography (SPECT/CT) scanner with two commonly used colloidal lymphatic radiotracers--99mTc-antimony sulfide colloid (ASC) and 99mTc-filtered sulfur colloid (FSC) in the setting of low-stage non-small cell lung cancer (NSCLC).

METHODS

Patients undergoing CT-guided percutaneous lung biopsies for clinically suspected early-stage lung cancer were randomized to peri-lesional injection of 37 MBq (0.5 mL) of either ASC or FSC. SPECT/CT of the thorax was performed at either 1, 2, or 3 h post-injection. The images were reviewed to determine if lymph node activity separate from the injection site could be identified.

RESULTS

24 patients were included. Lymph node activity was identified in 50% of patients. A total of 15 lymph nodes with activity were visualized including 5 ipsilateral hilar, 6 ipsilateral mediastinal, and 4 distant locations. No contralateral mediastinal or hilar activity was visualized. There was a tendency to improved visualization with ASC and the longer 3 h wait time. Most patients also demonstrated significant pleural, tracheobronchial, and/or systemic activity.

CONCLUSIONS

SPECT/CT imaging can demonstrate lymph node activity separate from the injection site in at least some low-stage NSCLC patients with a perilesional injection of 99mTc nanocolloid tracers. Further investigation into the role of pre-operative lymphoscintigraphy with SPECT/CT in patients with lung cancer is warranted.

Identification of metastatic nodal disease in a phase 1 dose-escalation trial of intraoperative sentinel lymph node mapping in non-small cell lung cancer using near-infrared imaging

OBJECTIVES

Early-stage non-small cell lung cancer (NSCLC) has a high recurrence rate and poor 5-year survival, particularly if lymph nodes are involved. Our objective was to perform a dose-escalation study to assess safety and feasibility of intraoperative near-infrared (NIR) fluorescence imaging to identify the first tumor-draining lymph nodes (ie, sentinel lymph nodes [SLNs] in patients with NSCLC).

METHODS

A-dose escalation phase 1 clinical trial assessing real-time NIR imaging after peritumoral injection of 3.8 to 2500 μg indocyanine green (ICG) was initiated in patients with suspected stage I/II NSCLC. Visualization of lymphatic migration, SLN identification, and adverse events were recorded.

RESULTS

Thirty-eight patients underwent ICG injection and NIR imaging via thoracotomy (n = 18) or thoracoscopic imaging (n = 20). SLN identification increased with ICG dose, with fewer than 25% SLNs detected in dose cohorts of 600 μg or less versus 89% success at 1000 μg or greater. Twenty-six NIR(+) SLNs were identified in 15 patients, with 7 NIR(+) SLNs (6 patients) harboring metastatic disease on histologic analysis. Metastatic nodal disease was never identified in patients with a histologically negative NIR(+) SLN. No adverse reactions were noted.

CONCLUSIONS

NIR-guided SLN identification with ICG was safe and feasible in this initial dose-escalation trial. ICG doses greater than 1000 μg yielded nearly 90% intrathoracic SLN visualization, with the presence or absence of metastatic disease in the SLN directly correlating with final nodal status of the lymphadenectomy specimen. Further studies are needed to optimize imaging parameters and confirm sensitivity and specificity of SLN mapping in NSCLC using this promising imaging technique.

Developing intrathoracic sentinel lymph node mapping with near-infrared fluorescent imaging in non-small cell lung cancer

With poor survival and high recurrence rates, early-stage lung cancer currently appears to be understaged or undertreated, or both. Although sentinel lymph node biopsy is standard for patients with breast cancer and melanoma, its success has been unreliable in non-small cell lung cancer. Sentinel lymph node biopsy might aid in the identification of lymph nodes at the greatest risk of metastasis and allow for more detailed analysis to select for patients who might benefit from adjuvant therapy. The early results in our recent clinical trial of patients with early-stage lung cancer have suggested that near-infrared imaging might offer a platform for reliable sentinel lymph node identification in these patients.

Sentinel nodes in lung cancer: review of our 10-year experience

Sentinel node (SN) identification in patients with lung cancer is useful not only to minimize lymph node dissection, but also to target the best lymph nodes for intraoperative frozen section during segmentectomy. Since 2000, we have identified the SN in lung cancer patients using radioisotope (RI). This review presents our data on SN identification, describing the following: the procedure, using a radioisotope tracer; the flow of Tc-99 tin colloid after the injection; the characteristics of patients whose SNs could not be identified; ex vivo SN identification; reliability of in vivo SN identification; the algorithm for reducing mediastinal lymph node dissection; the differences in SN identification between large and small radioisotope particles; SNs at segmental lymph nodes; SN navigation segmentectomy for clinical stage IA non-small cell lung cancer; and small metastasis in the SN.

Sentinel node identification using technetium-99m neomannosyl human serum albumin in esophageal cancer

BACKGROUND

This study is a clinical trial designed to test the reliability and feasibility of sentinel node detection using a new mannose receptor radioactive binding agent in patients with esophageal squamous cell carcinoma.

METHODS

Twenty-three patients (21 men, 2 women; mean age 61.0±8.60 years) who were candidates for esophagectomy with conventional lymph node dissection for thoracic esophageal cancer were enrolled. A total dose of 1 mCi of 99mTc-MSA [technetium-99m neomannosyl human serum albumin] in 0.2 mL was administered at 4 quadrants into the submucosal layer around the primary tumor under esophagoscopic guidance approximately 1 hour before surgery. Intraoperative sentinel node sampling was subsequently followed by esophagectomy. All harvested lymph nodes were cut into 2-mm slices and ultimately diagnosed using formalin-fixed and paraffin-embedded sections with hematoxylin and eosin staining.

RESULTS

The number of dissected lymph nodes per patient was 30.5±9.18 (15-47). Among 23 patients, the sentinel lymph nodes could be identified in 21 patients (91.3%). The sentinel nodes could be identified in all 21 patients with cT1 or T2N0M0 (100%) disease; these patients were candidates for sentinel lymph node navigation surgery for the esophageal cancer. The mean number of sentinel nodes identified was 2.6±1.35 (range, 1-5) per patient. No false-negative sentinel lymph nodes were detected in any of the 8 patients with node-positive disease (0%).

CONCLUSIONS

Intraoperative sentinel lymph node identification using 99mTc-MSA was feasible and reliable in patients with esophageal squamous cell carcinoma.