Anatomy and Localization
The precise localization and designation of the resection site are of great importance for oncological surgery and staging. In clinical practice, a classification has been established based on a modification of the Naruke scheme by Mountain and Dresler (1), published by both the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer (UICC). With minor discrepancies, especially in the Asian region, a further revision was carried out by the International Association for the Study of Lung Cancer, resulting in the IASLC lymph node map.
Therapeutic Algorithm and Treatment Alternatives
A tumor involvement of the mediastinal lymph nodes of a non-small cell lung carcinoma means ipsilateral N2 and contralateral N3 involvement.
Particularly, the patient group in UICC Stage III is very heterogeneous and requires careful pre-therapeutic diagnostics. Depending on the combination, Stage III results from T1-3 N2-3 M0 and T4 N0 M0. For planned curative therapy, histological confirmation of the mediastinal lymph nodes via EBUS (Endobronchial Ultrasound) or surgery is required. In addition to the access via video-assisted thoracoscopy (VATS), video-assisted mediastinal lymphadenectomy (VAMLA) or mediastinoscopy also represent good surgical alternatives for clarifying the mediastinal lymph node status. (2)
In the current guideline, for patients in Stage IIIA3 (lymph nodes N1 to N2) and the technical possibility of an R0 resection, surgery after neoadjuvant therapy or definitive radiochemotherapy is recommended. In the case of N3 involvement, surgical therapy is generally not indicated.
Techniques of Extraction
Another much-discussed topic is the method of performing a lymphadenectomy (3). Several studies have shown that minimally invasive systematic lymphadenectomy is not inferior in radicality to open surgery. However, more important than the access route is the surgical technique of lymph node removal. Here, the professional societies demand systematic or lobe-specific systematic lymph node dissection for a curatively intended operation.
The different definitions of lymph node removal (4)
| Selective LN Biopsy | Biopsy of at least 1 macroscopically suspicious lymph node |
| LN Sampling | Removal of at least 1 representative LN based on macroscopic findings or pre-op imaging |
| Systematic LN Dissection | Systematic resection of mediastinal tissue with LN along anatomical landmarks. Clearing of at least 3 mediastinal stations, station 7 is mandatory. Dissection of hilar and intrapulmonary LN. Separate pathological processing is required. |
| Lobe-specific Systematic LN Dissection | Systematic LN dissection with selection of stations based on the affected lobe |
| Extended LN Dissection | Bilateral mediastinal and cervical lymph node dissection, which can only be performed via sternotomy and neck exposure |
Survival Benefit and Complications
After examining numerous prospective studies in the current guideline, a significantly improved survival after systematic lymph node dissection compared to lymph node sampling is evident, mainly due to a higher rate of N2 detection. In comparison of complication rates, a significantly increased occurrence of specific complications (postoperative bleeding, chylothorax, recurrent nerve palsy) is observed after systematic lymph node dissection. Considering the improved overall survival through more accurate staging and the generally good manageability of specific complications, the guideline requires systematic lymph node dissection in every curative operation. (5, 6, 7)