Lung Cancer

The incidence of lung cancer has been on the rise since the early 1930s, and lung cancer is now by far the most common cancer in the Western world. It has been the leading cause of cancer
death in males for more than half a century. In recent years, the number of female smokers has relatively increased and now more than 30% of all new cases are women. In addition, the rate of cigarette consumption has been on a sharp rise in Eastern and developing countries. The mortality of lung cancer has barely improved over the past 40 years, with an overall 5-year survival rate of less than 10%.
Pathological subtype Frequency
Squamous cell cancer 35–45%
Adenocarcinoma 15–50% (large regional variation)
Large cell carcinoma 10%
Mixed forms 10–20%
Others: carcinoid, sarcoma etc. 2%
Small cell carcinoma 20% (considered disseminated at
presentation in most cases) Lung cancer is staged using the TNM system which has been shown to a correlate with prognosis. The classification is given in Table 2.1. The purpose of staging is to separate those patients whose tumors are operable from those whose are not. The best chance of a long-term cure is the complete surgical resection of the tumor, but only 1 in 5 patients are operable at the time of presentation. The fact that almost 40% of patients who were considered to have operable T1 lesions are dead within five years
suggests that staging needs to be improved.

TABLE 2.1. TNM Classification and Stage Grouping
DEFINITION OF TNM
Primary Tumor (T)
IX Primary tumor cannot be assessed, or tumor proven by the presence of malignant cells in sputum or bronchial washings but not visualized by imaging or bronchoscopy T0 No evidence of primary tumor Tis Carcinoma in situ T1 Tumor 3cm or less in greatest dimension, surrounded by lung or visceral pleura, without bronchoscophic evidence of invasion more proximal than the lobar bronchus,* (i.e., not in the main bronchus) T2 Tumor with any of the following features of size or extent: More than 3cm in greatest dimension Involves main bronchus, 2 cm or moredistal to the carina Invades the visceral pleura Associated with atelectasis or obstructivepneumonitis that extends to the hilar region but does not involve the entire lung T3 Tumor of any size that directly invades any of the following: chest wall (including superior sulcus tumors), diaphragm, mediastinal pleura, parietal pericardium; or tumor in the main bronchus less than 2cm distal to the carina, but without involvement of the carina; or associated atelectasis or obstructive pneumonitis of the entire lung T4 Tumor of any size that invades any of the following:mediastinum, heart, great vessels, trachea, esophagus, vertebral body, carina;
or separate tumor nodules in the same lobe; or tumor with malignant pleural effusion**
*Note: The uncommon superficial tumor of any size with its invasive component limited to the bronchial wall, which may extend proximal to the main bronchus, is also classified T1.
**Note: Most pleural effusions associated with lung cancer are due to tumor. However, there are a few patients in whom multiple cytopathologic examinations of pleural fluid are negative for tumor. In these cases, fluid is non-bloody and is not an exudate. Such patients may be further
evaluated by videothoracoscopy (VATS) and direct pleural biopsies. When these elements and clinical judgment dictate that the effusion is not related to the tumor, the effusion should be excluded as a staging element and the patient should be staged T1, T2, or T3. Regional Lymph Nodes (N) NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastasis N1 Metastasis to ipsilateral peribronchial and/or ipsilateral hilar lymph nodes, and intrapulmonary nodes including involvement by direct extension of the primary tumor
TABLE 2.1. Continued
N2 Metastasis to ipsilateral mediastinal and/or subcarinal lymph nodes(s) N3 Metastasis to contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph nodes(s)
Distant Metastasis (M)
MX Distant metastasis cannot be assessed M0 No distant metastasis M1 Distant metastasis present
Note: M1 includes separate tumor nodule(s) in a different lobe (ipsilateral or contralateral).
STAGE GROUPING
Occult Carcinoma TX N0 M0
Stage 0 Tis N0 M0
Stage IA T1 N0 M0
Stage IB T2 N0 M0
Stage IIA T1 N1 M0
Stage IIB T2 N1 M0
T3 N0 M0
Stage IIIA T1 N2 M0
T2 N2 M0
T3 N1 M0
T3 N2 M0
Stage IIIB Any T N3 M0
T4 Any N M0
Stage IV Any T Any N M1
Source: Used with the permission of the American Joint Committee on
Cancer (AJCC), Chicago, Illinois. The original source for this material is
the AJCC Cancer Staging Manual, Sixth Edition (2002) published by
Springer-New York, www.springeronline.com.