Mediastinal Staging of Non-Small-Cell Lung Cancer

Christian Lloyd, MD, and Gerard A. Silvestri, MD, FCCP, Division of Pulmonary and Critical Care Medicine at the Medical University of South Carolina, Charleston.

Cancer Control. 2001;8(4) 

In This Article

Abstract and Introduction

Abstract

Background:

The goal of preoperative staging of non-small-cell lung cancer (NSCLC) is to identify patients who will benefit from surgical resection. Various imaging and less invasive modalities are now available to improve therapy decision making.

Methods:

The available staging methods are reviewed, including conventional methods, surgical staging, and less invasive means of pathologic staging.

Results:

Computed tomography alone is not sufficiently accurate to stage the mediastinum, and further definitive testing is usually indicated. Positron emission tomography, along with mediastinal biopsy techniques using transbronchial needle aspiration or endoscopic ultrasound, has the potential to improve the accuracy of pretreatment staging.

Conclusions:

Every effort should be made to accurately discriminate between benign and malignant mediastinal disease. With further research on the proper roles of these new imaging modalities, they will become more widely used and will improve the accuracy of pretreatment staging of NSCLC.

Introduction

Bronchogenic carcinoma is the leading cause of cancer death in both men and women. In 2001, it is estimated that more than 169,000 people in the United states will be diagnosed with lung cancer and 157,000 people will die of the disease.[1] Non-small cell lung carcinoma (NSCLC) accounts for approximately 80% of all bronchogenic carcinomas, with small-cell lung carcinoma (SCLC) accounting for the remainder. After primary pathologic diagnosis of lung cancer, staging becomes the most important task. The staging process begins by evaluating the position and size of the primary tumor. Next, extent of spread tothoracic structures, including mediastinal lymphatic,and to extrathoracic organs is assessed in order to distinguish resectable from unresectable disease.

With better understanding of prognosis and new advances in treatment, the staging of lung cancer is a constantly evolving process. In 1997, the staging system of NSCLC was changed to provide greater specificity for identifying patients with similar prognosis and treatment options.[2] TNM staging as defined by this consensus is beyond the scope of this article but is reported elsewhere.[2,3]

In general, stage I-II disease is treated with surgery alone. Mediastinal involvement is an ominous sign for prognosis and is important for determining respectability.Stage III (locoregional disease) has historically been treated with chemotherapy and radiotherapy. Recent studies[4,5,6] suggest that surgery may be added to the chemotherapy and radiotherapy for certain subgroups of patients. Stage IIIB disease with contralateral mediastinal involvement is a contraindication to surgery.Finally, chemotherapy or supportive care is preferred for most stage IV disease. In rare instances, surgery has been offered for resection of a primary lung tumor with concomitant resection of an isolated brain metastasis.

The first step in mediastinal staging involves radiographic imaging with contrasted computed tomography(CT). Lymph nodes are defined as pathologic based solely on short axis size greater than 1 cm.[7] However, CT is not sufficiently accurate to solely stage the mediastinum, and further definitive testing is usually indicated. If there is evidence of mediastinal adenopathy, imaging is then followed by mediastinal sampling, usually through mediastinoscopy. If there is no evidence of mediastinal adenopathy on CT, some thoracic surgeons sample the mediastinal lymph nodes at the time of thoracotomy. The goal of preoperative staging is to identify patients who would not benefit from surgical resection, thus avoiding the morbidity and mortality associated with major thoracic surgery.These patients often have significant pulmonary and cardiovascular comorbidity secondary to age and tobacco use. This review examines the methods used to stage NSCLC, including newer staging techniques(positron emission tomography imaging), less invasive means of pathologic staging (transbronchial lymph node sampling,percutaneous transthoracic needle aspiration,and endoscopic ultrasound-guided fine-needle aspiration of the mediastinum),as well as the more conventional techniques.

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