Networks: NSCLC staging, MAPAH, cough in teen athletes

Interventional Chest/Diagnostic Procedures

Update: 8th ed IASLC lung cancer staging guidelines

The new 8th edition guidelines on the staging of non-small cell lung cancer sponsored by the International Association for the Study of Lung Cancer (IASLC), and developed jointly by the American Joint Committee on Cancer and the Union Internationale Contre le Cancer were enacted January 1, 2017, and provide a methodologically rigorous update to staging nomenclature (Detterbeck et al. Chest. 2017;151[1]:193). The new guidelines were developed using a database comprising 94,708 patients in 16 countries, integrating clinical, pathologic, and survival data with multivariate analysis to establish prognostically significant staging subgroups.

In the new guidelines, tumor size has been divided into 1-cm increments for T classifications with new subcategories of T1a <1 cm, T1b 1-2 cm, and T1c 2-3 cm (Rami-Porta et al. J Thorac Oncol. 2015;10[7]:990). Furthermore, T2 has been broadened to include main bronchus tumors causing lobar or whole lung atelectasis extending to the hilum. Tumors with diaphragmatic involvement have been reclassified as T4. Guidance on heterogeneous nodules has also been provided, with emphasis on measurement of the solid component (based on imaging) or depth of invasion (on pathology) to determine T classification.

The N classification remains unchanged from the 7th edition. Exploratory analysis suggested prognostic significance to the number of involved N1/N2 lymph nodes; however, this requires detailed pathologic assessment and was not adopted as a staging criterion (Asamura et al. J Thorac Oncol. 2015;10[12]:1675).

Classification of metastatic disease has been modified from M1a/M1b to M1a for thoracic metastasis, M1b for single/oligometastatic extrathoracic metastasis, and the new category M1c for multiple/disseminated metastases. M1c involvement now denotes stage IVb disease, with lower survival compared to IVa disease (0% vs 10% 5-year survival (Goldstraw et al. J Thorac Oncol. 2015;11[1]:39). Application in broader cohorts, including patients undergoing bronchoscopic staging, will be needed to further validate the new guidelines.

Vivek Murthy, MD

Fellow-in-Training MemberSteering Committee
 

Pulmonary Physiology, Function, and Rehabilitation

6-minute walk test

The 6-minute walk test (6MWT) is a widely used measure of functional status and exercise capacity. Though it does not diagnose specific etiologies of impairment, the 6MWT provides an assessment of the overall integrated physiologic responses to exercise (Am J Respir Crit Care Med. 2002;166[1]:111). The test is a self-paced, submaximal study. Patients are instructed to “walk as far as possible for 6 minutes” with this distance (6MWD) measured as the primary outcome. 6MWD is associated with clinical outcomes in many cardiopulmonary disorders and is reliable, valid, and responsive to treatment. Normative equations provide predicted and lower limit of normal values (Singh et al. Eur Respir J. 2014;44[6]:1447). In addition to patient comorbidities, several important factors impact 6MWD interpretation. Standardization of the testing course, patient instructions, encouragement, technician assistance, walking aids, and supplemental oxygen use are important in reducing testing variability (Holland et al. Eur Respir J. 2014;44[6]:1428). A significant learning effect exists during the first several walks. An improvement of about 26 m (range 24-29 m) has been reported in patients with COPD, with the majority improving during the second test despite a short time interval lapse. Assessing for longitudinal change in serial testing is based on the minimal clinically important difference (MCID). This represents the difference in 6MWD that is perceived as important to the patient or leads to change in management. Techniques to develop these estimates are based upon statistical analysis of study sample data (distribution-based) or changes in a different, but related, clinical variable that is used as a reference (anchor-based). While minor differences in MCID are reported based on specific disease processes, a European Respiratory Society/American Thoracic Society review based on data from patients with COPD, ILD, and PAH found a MCID value of about 30 m (range 25-33 m) for adults with chronic respiratory disease, independent of specific disease, which is only slightly larger than the short term variability (Puente-Maestu et al. Eur Respir J. 2016;47[2]:429). Knowledge of these factors can assist in proper interpretation of the 6MWT.

Lana Alghothani, MD

NetWork Member

Nitin Bhatt, MD

Steering Committee Member

Pulmonary Vascular Disease

Methamphetamine-associated pulmonary hypertension (MAPAH): “tip of the iceberg”

Pulmonary hypertension (PH) is a devastating condition with serious morbidity and mortality. The Evian Classification and more recent revisions (J Am Coll Cardiol. 2013;62(25 Suppl ):D34) reclassified PH into five subgroups based upon etio-pathogenesis. Group I PH (pulmonary arterial hypertension, PAH) represents a growing list of entities, with Drugs & Toxins (Group 1.3) as a separate subgroup. This subgroup was first recognized following the discovery of an association between PH and the ingestion of the anorexigen aminorex (Gurtner HP. Schweiz Med Wochenschr. 1985;115[24]:818).