12

STAGING OF LUNG CANCER

Susanne M. Arnold, MD

A 48-year-old female presents to her primary care physician with a 2-month history of shortness of breath. Chest radiographs reveal a large left upper lobe lung mass and a prominent mediastinum. A computed tomographic (CT) scan of the chest was performed and revealed enlarged aorticopulmonary window lymph nodes and pretracheal mediastinal adenopathy. She undergoes a bronchoscopy with biopsy of the lung mass and endobronchial ultrasound (EBUS)–guided biopsy of the mediastinal lymph nodes, both of which were positive for thyroid transcription factor-1 (TTF-1) adenocarcinoma consistent with lung cancer. What additional tests are needed for completion of staging?

Learning Objectives:

1.   What are the current guidelines for staging of non–small cell lung cancer and small cell lung cancer by stage?

2.   What are the diagnostic modalities of choice for staging non–small cell and small cell lung cancer?

3.   How does the American Joint Committee on Cancer/International Association for the Study of Lung Cancer (AJCC/IASLC) eighth edition of its Cancer Staging Manual differ from prior versions of the staging system?

The standard nomenclature of the AJCC remains the tumor, node, metastasis (TNM) staging system, which is an internationally accepted mechanism to accurately describe the anatomic extent of cancer in the human at time of diagnosis. It not only allows communication across the world but also provides a framework for response assessment in clinical trials and the published record. On January 1, 2018, the eighth edition of the AJCC Cancer Staging Manual went into effect for all cancer types, including non–small cell and small cell lung cancer.^1,2 The IASLC revised the seventh edition of the AJCC manual, and both the IASCL and AJCC accepted the revision with the 2017 publication of the guidelines.^3,4 Concurrently, the National Comprehensive Cancer Network (NCCN) incorporated these changes into its guidelines.

While small cell carcinoma has traditionally been staged in a simplified nomenclature of “limited” versus “extensive” stage, the AJCC’s TNM staging system has been adopted for small cell lung cancer to improve the specificity and reliability in reproducibility of small cell lung cancer staging across countries and in clinical trials.

DIAGNOSTIC EVALUATION

The AJCC and NCCN guidelines also confirm the appropriate evaluation of patients with lung cancer. This includes clinical staging: physical examination, non-invasive radiographic evaluations, and laboratory evaluations (complete blood count, electrolytes, calcium, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, total bilirubin, creatinine, and albumin).⁵ The staging guidelines also include pathologic staging, which requires invasive staging procedures, such as fine-needle aspiration, mediastinoscopy, and thoracotomy. The diagnostic workup should also include evaluation for paraneoplastic syndromes, performance status, and other comorbidities that might limit treatment options. To date, serum tumor markers have not been shown to have benefit in the assessment of small cell or non–small cell lung cancer. Together, these measures provide an important assessment of extent of disease, organ involvement, and organ function and ability to tolerate systemic treatment.

The foundation of radiographic assessment of lung cancer is CT scanning, as well as positron emission tomographic (PET) scans. There are non-invasive methods to assess tumor size, metabolic activity, and location. Contrast-enhanced magnetic resonance imaging (MRI) or contrast-enhanced CT scan of the brain is indicated in all subjects with documented lung cancer greater than 1 cm because of the high rate of dissemination to the brain in this disease. Clinical symptoms should guide further radiographic assessment, including the symptoms of bone pain, suspected disseminated disease in liver, or other suspicious symptoms of metastasis.

Tissue biopsy is required in all cases of lung cancer, and core needle biopsy is the minimum procedure that should be performed because of the need for adequate tissue for genomic testing in many stages of lung cancer. In general, the least invasive procedure required to provide adequate documentation of the highest possible stage is recommended. Adequately staging lung cancer is critical to appropriate decision-making for treatment. Mediastinal nodal staging is a critical component of adequate staging, and mediastinoscopy is still considered the gold standard of mediastinal staging. EBUS is a newer modality used to stage mediastinal lymph nodes in a less invasive manner (Figure 12-1).

Figure 12-1. The International Association for the Study of Lung Cancer (IASLC) lymph node map, including the proposed grouping of lymph node stations into “zones.” (Reproduced with permission from Rusch VW, Asamura H, Watanabe H, Giroux DJ, Rami-Porta R, Goldstraw P. The IASLC lung cancer staging project: A proposal for a new international lymph node map in the forthcoming seventh edition of the TNM classification for lung cancer. J Thorac Oncol. 2009;4(5):568-577. doi:https://doi.org/10.1097/JTO.0b013e3181a0d82e. Copyright © 2009 International Association for the Study of Lung Cancer. Published by Elsevier Inc.)

While EBUS has become commonplace, one caveat to this procedure is that a negative EBUS biopsy of mediastinal lymph nodes that are suspected to be malignant (metabolically active on PET scan, enlarged greater than 2 cm, involvement of multiple nodes) require confirmatory surgical sampling to ensure adequate staging of the mediastinum.

Stay updated, free articles. Join our Telegram channel

Join