Extent of mediastinal node metastasis in clinical stage I non-small-cell lung cancer: The role of systematic nodal dissection1
Introduction
Nodal status is the most important factor influencing the prognosis in non-small-cell lung cancer (NSCLC). As clinical stage I lung cancer is not always pathological stage I cancer, systematic nodal dissection is necessary even in clinical stage I NSCLC, in order to clarify the correct nodal status. However, in high-risk cases, such as the elderly or those with poor cardiopulmonary function, the patients' condition excludes complete mediastinal nodal dissection. In these patients, non-curative operations are often performed to reduce the operative morbidity and mortality by sampling only some lymph nodes or performing non-systematic nodal dissection. Furthermore, video-assisted pulmonary resection for lung cancer has increased recently, particularly for clinical stage I lung cancer, although complete systematic nodal dissection is very difficult using this procedure. For these reasons, clarifying the incidence and mode of lymph node metastasis in clinical stage I lung cancer is very important. In the present study, we evaluated the patterns of mediastinal nodal metastasis in clinical stage I NSCLC in relation to size and location of the primary tumor, and histologic type by postoperative histopathologic examination of specimens from patients who had undergone both complete resection of the primary tumor and systematic nodal dissection.
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Patients and methods
Between January 1980 and December 1996, 582 patients with c-stage I NSCLC underwent resectional surgery at Kanazawa University Hospital, Japan. Among these patients, 524 patients who underwent lobectomy or pneumonectomy with systematic nodal dissection were evaluated in this article (Table 1). Another 58 patients who underwent less than lobectomy or non-systematic nodal dissection were excluded. Before the operation, each patient underwent a physical examination, blood chemistry analysis, plain
Results
Of the 524 cases, the pN status was N0 in 409 patients (78%), N1 in 44 patients (8%), N2 in 67 patients (13%), and N3 in four patients (0.8%) (Table 2). Among the 71 patients with pN2 or pN3 disease, 36 patients had single-level metastasis and 35 patients had multi-level metastasis. The nodes in 38 patients were out of reach of the mediastinoscope (levels 5, 6, 8, and 9). The average number of dissected lymph nodes at each operation was 14.3±6.5.
The distribution of the pN status according to
Discussion
We routinely perform systematic nodal dissection in lung cancer patients even for clinical stage I NSCLC because of the relatively high false negative rate of CT scanning 1, 5. Determination of how primary lesions metastasize to the mediastinal lymph nodes and where the prevalent sites of nodal metastasis are, is important for successful surgical treatment of patients with lung cancer. Slight modifications of the lymph node map proposed by Naruke et al. [3], approved by the Japan Lung Cancer
Conclusions
Systematic mediastinal nodal dissection should be routinely performed for clinical stage I lung cancer to ensure the correct nodal status, but it might be dispensable in the patients with peripheral squamous cell carcinoma ≤20 mm in diameter, with central squamous cell carcinoma ≤30 mm, and with adenocarcinoma ≤10 mm. When systematic nodal dissection cannot be performed, the incidence and extent of nodal metastases should be taken account with respect to histologic type, size, and location of
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- 1
Presented at the 8th World Conference on Lung Cancer, 10–15 August 1997, Dublin, Ireland.