Lung cancer staging is the assessment of the extent to which a lung cancer has spread from its original source. As with most cancers, staging is an important determinant of treatment and prognosis. In general, more advanced stages of cancer are less amenable to treatment and have a worse prognosis.
The initial evaluation of non-small cell lung cancer staging uses the TNM classification. This is based on the size of the primary tumor, lymph node involvement, and distant metastasis. After this, using the TNM descriptors, a group is assigned, ranging from occult cancer, through stage 0, IA (one-A), IB, IIA, IIB, IIIA, IIIB to IV (four). This stage group assists with the choice of treatment and estimate of prognosis.
There are several methods by which this assessment is made. They are broadly classified into non-invasive techniques, which generally involve medical imaging of the lungs such as computer tomography (CT) scans and PET scans, and invasive techniques such as biopsy and surgery. Invasive techniques provide additional information because tissue samples can be examined under a microscope to confirm presence of cancer cells (as opposed to enlargement of tissues due to other causes such as infection) and to determine the type of lung cancer and its grade.
Staging may also be categorized as either clinical or as pathological/surgical staging. Clinical staging is performed prior to definitive surgery. It is based on the results of imaging studies (such as CT scans ) and biopsy results (i.e. clinical staging does include the results of biopsy, an "invasive technique.") Pathological staging is also called surgical staging and reflects not only the results of non-surgical biopsy, but is evaluated either intra- or post-operatively and is based on the combined results of surgical and clinical findings, including surgical sampling of thoracic lymph nodes.Lu Charles, Onn A, Vaporciyan AA et al. Holland-Frei Cancer Medicine. 8th edition. Chapter 78: Cancer of the Lung. People's Medical Publishing House, USA (2010)
Lung cancer
Lung cancer is responsible for 1.3 million deaths worldwide annually and is the most common cause of cancer-related death in men and the second most common in women. According to the World Health Organization, lung cancer was responsible for approximately 10 million deaths in 2020. The most common cause of lung cancer is long-term exposure to tobacco smoke, and the carcinogens are typically found in cigarettes. In the United States, around 80%-90% of lung cancer deaths are among cigarette smokers. Lung cancer in non-smokers, who account for approximately 15% of cases, is often attributed to a combination of genetic factors, and exposure to radon gas, asbestos, and air pollution. The main types of lung cancer are non-small cell lung carcinoma and small cell lung carcinoma, the two being distinguished histologically as well as by how they are treated; non-small cell lung carcinoma is primarily treated with surgery if feasible, while small cell lung carcinoma is more frequently treated with chemotherapy and radiation.
The diagnosis of lung cancer is based on chest radiograph and computed tomography (CT) scans, and is confirmed by biopsy. Biopsy is usually performed via bronchoscopy or CT-guided biopsy. Treatment and prognosis depend upon the histological type of cancer, the stage, and the patient's performance status. Treatments include surgery, chemotherapy, and radiotherapy.
Pattern of progression
Lung cancer can start in various portions of the lung. From there it spreads in fairly predictable pattern. Typically, if lung cancer spreads, it first goes to nearby lymph nodes, followed by lymph nodes further away located between the lungs in a space called the mediastinum. In the mediastinum, the lung cancer tends at first to stay on the side where the original tumor started. Once it crosses the mediastinal midline, it denotes more advanced, surgically unresectable disease. Lung cancer can also spread to distant organs, such as the liver or adrenal glands, which constitutes the most advanced stage of the disease called stage IV.
Staging StagingWhat is Cancer Staging? American Joint Committee on Cancer 2010 May 5.http://www.cancerstaging.org/mission/whatis.html is the process of determining how much cancer there is in the body and where it is located. Staging of lung cancer is of paramount importance as treatment choices are often highly complex, even for physicians with much experience in the field, and the options largely depend on the stage of the disease. The underlying purpose is to describe the extent or severity of an individual's cancer, and to bring together cancers that have similar prognosis and treatment.
Staging information which is obtained prior to surgery, for example by x-rays and endoscopic ultrasound, is called clinical staging; staging by surgery is known as pathological staging.
Clinical staging is done by a combination of imaging and sampling (biopsies), or stated differently, non-invasive (radiological) and invasive (biopsy) methods.
Pathologic staging is more accurate than clinical staging, but clinical staging is the first and sometimes the only staging type. For example, if clinical staging reveals stage IIIB or IV disease, surgery is not helpful and no pathological staging information will be obtained (appropriately).
Lung cancer biopsies can be taken for two different reasons: Diagnosis: To find out whether an abnormality seen on a chest x-ray or CT scan is indeed lung cancer, and what histological type it is (small cell or non-small cell). Staging: To find out whether a structure, such as a lymph node in the mediastinum, has already been invaded by cancer or not. However, it is often possible, with proper planning, to obtain both diagnostic and staging information with a single biopsy procedure.
There is an extensive array of staging methods available, each with advantages and disadvantages. Many cancer treatment centers review newly diagnosed patients at an inter-disciplinary chest tumor board where radiologists, oncologists, surgeons, pulmonologists, pathologists and EUS specialists (endosonographers) discuss the relative merits of the available modalities and make a choice by consensus.
TNM classification
The TNM staging system for lung cancer as defined by the 9th Edition of the TNM Classification (International Association for the Study of Lung Cancer [IASLC], American Joint Committee on Cancer [AJCC], and Union for International Cancer Control [UICC]) is as follows:
T – Tumor (primary tumor)
Tx: Primary tumor cannot be assessed. T0: No evidence of primary tumor. Tis: Carcinoma in situ. T1: Tumor surrounded by lung or visceral pleura or located in a lobar or more peripheral bronchus. T1mi: Minimally invasive adenocarcinoma. T1a: Tumor ≤ 1 cm in greatest dimension. T1b: Tumor > 1 cm but ≤ 2 cm. T1c: Tumor > 2 cm but ≤ 3 cm. T2: Tumor with any of the following features: T2a: Tumor > 3 cm but ≤ 4 cm in greatest dimension; invasion of visceral pleura; invasion of adjacent lobe; involvement of main bronchus (not including carina); or associated atelectasis/obstructive pneumonitis. . T2b: Tumor > 4 cm but ≤ 5 cm in greatest dimension. T3: Tumor > 5 cm but ≤ 7 cm; or invading parietal pleura, chest wall, phrenic nerve, pericardium, or other defined structures; or separate tumor nodule(s) in same lobe. T4: Tumor > 7 cm; or invasion of mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body/spiral structures; or separate tumor nodule(s) in a different ipsilateral lobe.
N – Regional lymph nodes
Nx: Regional lymph nodes cannot be assessed. N0: No regional lymph node metastasis. N1: Metastasis in ipsilateral peribronchial and/or hilar lymph nodes, including by direct extension. N2: Metastasis to ipsilateral mediastinal and/or subcarinal lymph node stations. N2a: Metastasis(es) in a single ipsilateral mediastinal or in the subcarinal nodal station. N2b: Metastases in multiple ipsilateral mediastinal nodal stations with or without involvement of the subcarinal nodal station. N3: Metastasis in contralateral mediastinal/hilar lymph nodes or in scalene/supraclavicular nodes.
M – Distant metastasis
M0: No distant metastasis. M1a: Tumor with pleural or pericardial nodules or malignant pleural or pericardial effusions, separate tumor nodule(s) in a contralateral lob. M1b: Single extrathoracic metastasis. M1c1: Multiple extrathoracic metastases in a single organ system. M1c2: Multiple extrathoracic metastases in multiple organ systems.
Methods
AJCC edition published went into effect Lung cancer link(s) and page numbers in the original 7 2009 2010 AJCC, NCI, and NCCN 6 2002 2003 AJCC;AJCC Cancer Staging Manual 6th edition; Chapter 19; Lung - original pages 167-177http://www.cancerstaging.org/products/csmanual6ed-4.pdf original pages 167-177 5 1997 1998 AJCC;AJCC Cancer Staging Manual 5th edition; Chapter 19; Lung - original pages 127-137http://www.cancerstaging.org/products/csmanual5ed_3.pdf original pages 127-137 4 1992 1993 AJCC;AJCC Cancer Staging Manual 4th edition; Chapter 19; Lung - original pages 115-122 original pages 115-122 3 1988 1989 AJCC;AJCC Cancer Staging Manual 3rd edition; Chapter 18; Lung - original pages 114-121http://www.cancerstaging.org/products/csmanual3ed_2.pdf original pages 114-121 2 1983 1984 AJCC;AJCC Cancer Staging Manual 2nd edition; Chapter 16; Lung - original pages 99-105http://www.cancerstaging.org/products/csmanual2ed.pdf original pages 99–105 1 1977 1978 AJCC;AJCC Cancer Staging Manual 1977; Chapter 6; Lung - original pages 59-64http://www.cancerstaging.org/products/csmanual1ed.pdf original pages 59–64
The American Joint Committee on Cancer (AJCC) as well as the International Union Against Cancer (UICC) recommend TNM staging, which is a two step procedure. Their TNM system, which they now develop jointly, first classifies cancer by several factors,A. De la Guerra. New TNM Classification for Lung Cancer - Part I: The changes. Doctors Lounge Website. http://www.doctorslounge.com/index.php/articles/page/340 T for tumor, N for nodes, M for metastasis, and then groups these TNM factors into overall stages as shown in their table.AJCC Cancer Staging Manual, 7th edition, updated Cancer Staging Posters.
AJCC has provided web accessible poster versions of these copyrighted TNM descriptors and stage groups, to which readers are directed for accurate, detailed, up to date information; additionally, both the National Cancer Institute (NCI) and the National Comprehensive Cancer Network (NCCN)NCCN Guidelines for patients: non-smallcell lung cancer; 2010. reprint these descriptors and grouping tables with AJCC permission, and extensively discuss staging modalities and treatment options, providing expert clear assistance in decisions about the best treatments. The NCCN pathways "outline the step-by-step treatment decisions from diagnosis through all phases of treatment and survivorship."
Although TNM classification is an internationally agreed system, it has gradually evolved through its different editions; the dates of publication and of adoption for use of AJCC editions is summarized in the table in this article; past editions are available from AJCC for web download.American Joint Committee on Cancer. Past Editions of the AJCC Cancer Staging Manual available at Therefore, it is important when reviewing reports of treatment or prognosis to be aware that the criteria used in the TNM system have varied over time, sometimes fairly substantially, according to the different editions. Literature reports usually reflect the staging that was in use while the study was initiated and performed, rather than when it was eventually published. The dates of publication and adoption for use of AJCC editions is summarized here to assist readers in understanding which era is being used by the literature.