CONTENTS: Tests for Lung Cancer
6.2 Methods of Obtaining Lung Tissue for Diagnosis
6.2.1 Guidelines for Tissue Sampling
6.2.2 ‘Minimally Invasive’ versus ‘Invasive’ Biopsy Procedures
6.2.3 Sputum Cytology
6.2.4 Bronchoscopic Biopsy Techniques
i. Endobronchial-Guided Transbronchial Needle Aspiration (EBUS-TBNA)
ii. Endoscopic Ultrasound-Guided Fine Needle Aspiration (EUS-FNA)
iii. Electromagnetic Navigational Bronchoscopy (EMN)
6.2.5 Transthoracic Biopsy Techniques:
i. Transthoracic (Percutaneous) Needle Aspiration/Biopsy (TTNA/B)
ii. Standard Cervical Mediastinoscopy (SCM)
iii. Video-Assisted Thoracoscopic Surgery (VATS)
6.2.6 Sampling the Pleura
i. Thoracentesis
ii. Pleural Biopsy
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6.2 Tests for Lung Cancer: Methods of Obtaining Lung Tissue for Diagnosis
For individuals who undergo lung cancer screening the hope is to detect lung cancer at an early stage, when it is more amenable to treatment. But for non-screened individuals, approximately 65 % to 75 % of patients with Non Small-Cell Lung Cancer (NSLC) present with advanced-stage disease that is not amenable to surgery. For this non-screened group, the diagnosis is frequently made on small biopsy and cytology specimens.
If a lung tumor is present, imaging with contrast-enhanced computed tomographic (CT) scan of the chest and upper abdomen may be performed to assess the stage prior to biopsy. If imaging shows suspected metastases, some patients may require additional imaging such as positron emission tomography (PET) or integrated PET/CT (e.g., for stage IB to IIIA NSCLC to detect occult metastases).
6.2.1 Guidelines for Tissue Sampling
The clinical team will follow the guidelines and recommendations below before taking tissue samples:-
- The Tumor Node Metastasis (TNM) staging of NSCLC (Goldstraw et al., 2007)
- Guidelines issued by the ACCP (Alberts et al., 2007)
- The IASLC lymph node map (Rusch et al., 2009)
- The IASLC/ATS/ERS guidelines (Travis et al., 2011)
- The ACCP evidence-based clinical practice guidelines (Silvestri et al., 2013)
- The revised ESTS Guidelines for preoperative mediastinal lymph node staging (De Leyn et al., 2014)
6.2.2 ‘Minimally Invasive’ versus ‘Invasive’ Biopsy Procedures
The clinical physician has a number of minimally invasive and invasive procedures to biopsy a patient if he suspects NSCLC. The choice of site depends upon operator proficiency, patient safety and eventual goals for treatment. Minimally invasive techniques are obviously preferable to invasive one but they tend to be less sensitive so an additional biopsy may be necessary.
Other tests for lung cancer is sputum cytology. Indeed, sputum cytology is often the first diagnostic step in patients with central lung lesions. The presence of relevant tumor cells in the sputum specimen is vital for the accuracy of the test. In addition, the handling and preservation of the sputum specimen is also important. Fiberoptic bronchoscopy (FB) is the most useful test for central lesions, where bronchial brushing and washing samples may be obtained.
For peripheral lung lesions, the sensitivity of navigational bronchoscopy (R-EBUS, and TTNA) is greater than that of conventional bronchoscopy. Newer and less invasive procedures, such as EBUS-TBNA, mean that fine needle aspiration (FNA) for cytology examination are usually the primary means of diagnosis. Furthermore, accurate molecular and histological subtyping is now possible, even with needle aspirates of lung lesions or lymph nodes.
6.2.3 Sputum Cytology
Sputum cytology has diagnostic value when large, centrally located lung lesions are present, rather than small, peripheral lesions. It does not accurately stage lung cancer.
6.2.4 Bronchoscopic Biopsy Techniques
There are multiple bronchoscopic techniques including forceps biopsy, brushings, ultrasound and needle aspiration and these increase the sensitivity for the diagnosis and staging of lung cancer.
Bronchoscopy is best for accessing large, visible, or central lung lesions and suspected paratracheal, sub-carinal and hilar lymph nodes.
Conventional flexible bronchoscopy with forceps biopsy, brushing, or washing is best for accessing large, central lung tumors and those with airway involvement.
Two major limitations of standard flexible bronchoscopy are the inability to reach peripheral lung segments and the limited diagnostic tissue obtained from lesions less than 3 cm in diameter. CT-guided percutaneous biopsy is an alternative test to bronchoscopy. However, the possible complications of CT guided biopsy include hemorrhage and pneumothorax.
i. Endobronchial-Guided Trans-bronchial Needle Aspiration (EBUS-TBNA)
Endobronchial-guided, trans-bronchial needle aspiration (EBUS-TBNA) is the first-choice technique for sampling large, central lesions and suspicious mediastinal lymph nodes. The limitations of EBUS-TBNA include its inability to access mediastinal lymph node stations and the variable rates of operator proficiency.
Bronchoscopic TBNA can be performed based on CT imaging or under real-time guidance by endobronchial ultrasound. Endobronchial ultrasound (EBUS) requires a special bronchoscope and image processors distinct from conventional flexible bronchoscopes. EBUS has a sensitivity of 73 % to 85 % for large, central, symptomatic or visible lung lesions.
ii. Endoscopic Ultrasound-Guided Fine Needle Aspiration (EUS-FNA)
Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is a sensitive staging tool for suspected lung cancer involvement in sub-carinal and paratracheal lymph nodes. EUS-FNA can be combined with EBUS-TBNA to enhance mediastinal staging.
iii.Electromagnetic Navigational Bronchoscopy (EMN)
Electromagnetic navigational bronchoscopy (EMN) is a promising modality for sampling peripheral lung lesions but is a technique that is not widely available.
Electromagnetic navigational bronchoscopy (ENB) systems have been approved by the US Food and Drug Administration (FDA) to guide endoscopic diagnosis in the respiratory tract. Recently published studies have shown that the diagnostic yield of ENB for small peripheral lung lesions are between 54% to 77%.
6.2.5 Transthoracic Biopsy Techniques
Transthoracic biopsy techniques have a risk of complications, such as pneumothorax, which make them a less likely first-choice diagnostic procedure.
i. Transthoracic (Percutaneous) Needle Aspiration/Biopsy (TTNA/B)
This is a sensitive procedure for acquiring tissue for most intraparenchymal lung lesions, particularly peripheral nodules. Transthoracic Needle Aspiration (TNA) may also be used when lung tumors appear to involve the chest wall and as an alternative procedure when tumors cannot be safely accessed using another sampling technique.
TTNB has a sensitivity of 74 % to 90 % and can access most intraparenchymal lesions and almost all mediastinal lymph nodal stations. However, traversing the pleural space and lung tissue is frequently unavoidable resulting in high rates of pneumothorax (on average 10 to 15 %).
ii. Standard Cervical Mediastinoscopy (SCM)
SCM is a sensitive staging procedure for sampling lymph node stations and may use video mediastinoscopy and systematic lymph node sampling.
iii. Video-Assisted Thoracoscopic Surgery (VATS)
VATS is an accurate technique to assess the extent of invasion (chest wall, mediastinal) by the primary lung tumor (T) and mediastinal lymph node (and pleural) involvement (M). But it requires general anesthesia and carries higher morbidity and mortality than other diagnostic or staging techniques. VATS is most often used when alternative procedures cannot access the primary tumor or when they are non-diagnostic.
6.2.6 Sampling the Pleura
Sampling the pleural space (effusions or solid lesions) is essential in all patients with suspected pleural involvement.
i.Thoracentesis
Thoracentesis is performed as a first-line technique for evaluation of pleural effusions. Pleural biopsy (image-guided or thoracoscopic) is performed when pleural fluid cytology is negative or to obtain tissue from a solid pleural lesion. Thoracentesis removes fluid from the pleural space for cytologic analysis.
ii. Pleural Biopsy
If the pleural fluid cytology is negative a surgeon may perform a pleural biopsy.
References:
Alberts WM. (2007). Introduction: Diagnosis and Management of Lung Cancer: ACCP Evidence-Based Clinical Practice Guidelines (2nd Edition). Chest 132(3), 20S-22S. (Retrieved 19th Feb 2015): http://journal.chestnet.org/article/S0012-3692(15)35508-2/fulltext
Ernst A, Silvestri GA, Johnstone D. (2003). American College of Chest Physicians Interventional pulmonary procedures: Guidelines from the American College of Chest Physicians. Chest. 123(5), 1693. (Retrieved 19th Feb 2015): http://journal.chestnet.org/article/S0012-3692(15)33706-5/abstract
Patient Information
E-Medicine Health Bronchoscopy (Retrieved 25th April 2015): http://www.emedicinehealth.com/bronchoscopy/article_em.htm
Patient.co.uk Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (Retrieved 25th April 2015): http://www.patient.co.uk/health/endobronchial-ultrasound-guided-transbronchial-needle-aspiration
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