The impact of lymph node station on survival in 348 patients with surgically resected malignant pleural mesothelioma: implications for revision of the American Joint Committee on Cancer staging system
Tuesday, September 23rd, 2008.
The Journal of Thoracic and Cardiovascular Surgery. 2008 Sep;136(3):605-10. Epub 2008 Jun 27. [Link]
Flores RM, Routledge T, Seshan VE, Dycoco J, Zakowski M, Hirth Y, Rusch VW.
Thoracic Service, Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA. floresr@mskcc.org
Abstract
Objectives: The propensity of malignant pleural mesothelioma to metastasize to N1 or N2 nodes and their corresponding prognostic value is unclear. The American Joint Committee on Cancer staging system groups N1 and N2 disease together as stage III. The goal of this study was to define the prognostic value of specific nodal stations.
Methods: Patients with malignant pleural mesothelioma who underwent resection were identified from an institutional database. Nodal stations were defined by the American Joint Committee on Cancer lung cancer node map classification. Survival was analyzed by the Kaplan–Meier method, log-rank test, and Cox proportional hazards analysis.
Results: From 1990 to 2006, 348 patients were identified: 279 men and 69 women with a median age of 67 years (range 26–85 years). Extrapleural pneumonectomy was performed in 223 cases, and pleurectomy/decortication was performed in 125 cases. Survival differences (P < .01) were observed between 2 groups: N0 or N1(+) (median survival = 19 months) and N2(+), N2/N1(+) and internal thoracic(+) (median survival = 10 months). Survival was influenced by the number of involved N2 stations (0, 1, 2, or more: P < .001). Multivariate analysis grouping all N2 and internal thoracic(+) versus N1(+) and N0 demonstrated a hazard ratio for survival of 1.7 (P < .0001) controlling for T3/T4 status (hazard ratio = 1.3, P < .01), non-epithelioid histology (hazard ratio = 1.7, P < .0001), extrapleural pneumonectomy (1.1, P = .4), and male gender (hazard ratio 1.4, P < .01).
Conclusion: This study confirms a preferential pattern of drainage of malignant pleural mesothelioma to N2 rather than N1 lymph nodes, but suggests that N1 only nodal involvement should be classified as lower stage disease. Multiple N2 nodal site involvement could potentially be classified as higher stage disease than single station N2. Our results emphasize the need for larger, confirmatory multicenter studies that could lead to revision of the current staging system.
Glossary
- staging
- the process of finding out whether cancer has spread and if so, how far. There is more than one system for staging. The TNM system, described below, is one used often. The TNM system for staging gives three key pieces of information: T refers to the size of the Tumor N describes how far the cancer has spread to nearby Nodes M shows whether the cancer has spread (Metastasized) to other organs of the body Letters or numbers after the T, N, and M give more details about each of these factors. To make this information somewhat clearer, the TNM descriptions can be grouped together into a simpler set of stages, labeled with Roman numerals. In general, the lower the number, the less the cancer has spread. A higher number means a more serious cancer.
- resection
- surgery to remove part or all of an organ or other structure.
- lymph nodes
- small bean-shaped collections of immune system tissue such as lymphocytes, found along lymphatic vessels. They remove cell waste and fluids from lymph and help fight infections. Also called lymph glands.
- lymph
- (limf) clear fluid that flows through the lymphatic vessels and contains cells known as lymphocytes. These cells are important in fighting infections and may also have a role in fighting cancer.
- cancer
- malignancy; a group of diseases typified by abnormal, generally out-of-control, cell growth.
- mesothelioma
- a tumor derived from mesothelial tissue, such as the peritoneum (lining the abdomen) or pleura (lining the lungs). More on mesothelioma.
- extrapleural pneumonectomy
- (EPP) surgery to remove the pleura, diaphragm, pericardium, and entire lung involved with the tumor. You can view a web cast from Brigham and Women's Hospital in Boston of this procedure being done by Dr. David Sugarbaker: see the extrapleural pneumonectomy (EPP) web cast here.
