Lymphatic Mapping and Sentinel Lymphadenectomy for Primary and Metastatic Pulmonary Malignant Neoplasms

Abstract

Background: Mediastinal lymph node sampling understages a significant number of lung cancers, even when nodes are evaluated by immunohistochemical techniques. Intraoperative lymphatic mapping and sentinel lymphadenectomy allows focused pathologic evaluation of a few lymph nodes that accurately stage the entire basin. Hypothesis: Lymphatic mapping and sentinel lymphadenectomy is a practical and accurate method of staging lymph nodes that drain primary and metastatic neoplasms of the lung. Design and Setting: Retrospective review at a tertiary referral center. Patients: Sixty-seven patients undergoing resection of lung tumors. Main Outcome Measures: Sentinel lymph node (SN) identification rate, number of SNs, nodal pathologic features, and survival. Results: Twenty-eight patients had primary lung cancer and 39 had pulmonary metastases from melanoma (33 cases), squamous cell carcinoma (2 cases), colon cancer (2 cases), or other cancers (2 cases). Lymphatic mapping and sentinel lymphadenectomy was successful in all patients. The median number of lymph nodes identified by dye alone was 2 (range, 1-7); the median number identified by dye plus radiocolloid was 4 (range, 1-9). Most SNs (69%) were N1; 31% were N2. Lower lobe lesions drained to upper mediastinal nodes in 3 (13%) of 24 cases. Lymph node metastases were found in 11 patients with lung cancer (39%) and 8 patients with pulmonary metastases (21%). Ten (91%) of the 11 patients with lung cancer had SN involvement. In the 33 patients with metastatic melanoma, SN involvement significantly reduced the rate of 2-year survival (0% vs 48%). Conclusions: Lymphatic mapping and sentinel lymphadenectomy of intrapulmonary malignancies is technically challenging but feasible. Blue dye is most useful for in vivo identification of SNs; ex vivo radioactivity can confirm that excised nodes are SNs. Lymphatic mapping and sentinel lymphadenectomy can provide important prognostic information for patients with melanoma and lung metastases, and it may improve the staging of primary lung cancer.

Results of Initial Operations in Non–Small Cell Lung Cancer Patients With Single-Level N2 Disease

“…From the viewpoint of sentinel lymph node mapping, the results of recently launched clinical trials support the anatomical concept. While the percentage of skip metastasis in lung cancer patients with N2 disease has been reported to be around 20-40% [1][2][3][4][5][6][7], sentinel node mapping in non-small cell lung cancer patients in various stages revealed a similar percentage of mediastinal (N2) sentinel nodes of 16.7-31% with a high sensitivity rate of more than 90% [16][17][18]. Arguably, the direct drainage system appears the most plausible main channel of skip mediastinal nodal spread of cancer cells.…”

The problem of direct lymph drainage of the bronchopulmonary segments into the mediastinal and hilar lymph nodes

“…Soltesz et al (2005) suggested that the use of blue dye could not adequately identify the sentinel node in thoracic malignancies because of poor tissue penetration and the presence of anthracosis. Faries et al (2004) stated that blue dye was generally visible within subpleural lymphatic channels but might fade rapidly from anthracotic pulmonary lymph nodes ex vivo. Little et al (1999) adopted the position that anthracosis in intrathoracic lymph nodes caused a problem in identifying the blue node.…”

“…The mediastinal and interlobar surfaces were chosen because of the limited time of research during the autopsy and the greater probability of vessel visualization, which had been confirmed by prior tests. The used method was consistent with an intraoperative lymphatic mapping and sentinel lymphadenectomy, in which after injecting blue dye, the visceral pleura was closely observed to identify the blue-stained lymphatic channels leading to sentinel nodes (Faries et al, 2004). Sentinel nodes were examined by routine hematoxylin-eosin staining (Faries et al, 2004).…”

Dual-isotope lymphoscintigraphy using albumin nanocolloid differentially labeled with111In and99mTc

“…Its role is also being explored for other superficial cancers that spread preferentially by lymphatics such as melanoma [2], squamous cell carcinoma of the head and neck [3] and vulva [4]. The technique is also applicable to the staging of intracavitatory neoplasms such as lung [5] and colon [6] and in the correct clinical setting may be more accurate than any radiological staging technique including FDG-PET [7].…”