19 Lung
(Sarcomas and other rare tumors are not included.)
19
SUMMARY OF CHANGES
• The definitions of TNM and the Stage Grouping for this chapter have not changed from the Fifth Edition.
INTRODUCTION
Lung cancer is among the most common malignancies in the Western world and is the leading cause of cancer deaths in both men and women. It is one of the few tumors with a known carcinogen, namely tobacco, contributing to its etiol- ogy. In recent years we have come to appreciate that the initiation of lung cancer is a complex process that also involves certain biologic factors, such as the body’s ability to process carcinogens. This disease is usually not diagnosed early, and therefore the overall 5-year survival rate is approximately 15%. The treatment of lung cancer depends on the extent of disease, the location of the primary tumor, and the presence or absence of medical comorbidities. The assessment of extrapulmonary intrathoracic and extrathoracic metastasis is important for staging and patient evaluation.
ANATOMY
Primary Site. Carcinomas of the lung arise either from the alveolar lining cells of the pulmonary parenchyma or from the mucosa of the tracheobronchial tree.
The trachea, which lies in the middle mediastinum, divides into the right and left main bronchi, which extend into the right and left lungs, respectively. The bronchi then subdivide into the lobar bronchi for the upper, middle, and lower lobes on the right and the upper and lower lobes on the left. The lungs are encased in membranes called the visceral pleura. The inside of the chest cavity is lined by a similar membrane called the parietal pleura. The potential space between these two membranes is called the pleural space. The mediastinum con- tains the heart, thymus, great vessels, and other structures between the lungs.
The great vessels include:
Aorta
Superior vena cava Inferior vena cava Main pulmonary artery
Intrapericardial segments of the trunk of the right and left pulmonary artery Intrapericardial segments of the superior and inferior right and left pulmonary
veins
C34.0 Main bronchus C34.1 Upper lobe, lung C34.2 Middle lobe, lung
C34.3 Lower lobe, lung C34.8 Overlapping lesion of
lung
C34.9 Lung, NOS
The main anatomical subsites are shown in Figure 19.1:
C34.0: Main bronchus C34.1: Upper lobe C34.2: Middle lobe C34.3: Lower lobe
Regional Lymph Nodes. All regional lymph nodes are above the diaphragm.
They include the intrathoracic, scalene, and supraclavicular nodes. For purposes of staging, the intrathoracic nodes include the following:
Mediastinal:
Paratracheal (including those that may be designated tracheobronchial—that is, lower paratracheal, including azygous)
Pre- and retrotracheal (includes precarinal)
Aortic (includes aortopulmonary window, periaortic, ascending aortic, and phrenic)
Subcarinal Periesophageal
Inferior pulmonary ligament Intrapulmonary:
Hilar (proximal lobar) Peribronchial
Intrapulmonary (includes interlobar, lobar, and segmental)
Figure 19.2 illustrates lymph node maps of the lungs. All N1 nodes lie distal to the mediastinal pleural reflection and within the visceral pleura. All N2 nodes lie within the mediastinal pleural envelope on the ipsilateral side.
C34.1
C34.3 C34.1
C34.3
C34.3 C34.0
FIGURE 19.1. Anatomic subsites of the lung.
Distant Metastatic Sites. The most common metastatic sites are the brain, bones, adrenal glands, contralateral lung, liver, pericardium, and kidneys.
However, virtually any organ can be a site of metastases.
DEFINITIONS OF TNM
Primary Tumor (T)
TX 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 3 cm or less in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus(1)(i.e., not in the main bronchus) (Figure 19.3) T2 Tumor with any of the following features of size or extent (Figure 19.4):
• More than 3 cm in greatest dimension
• Involves main bronchus, 2 cm or more distal to the carina
• Invades the visceral pleura
• Associated with atelectasis or obstructive pneumonitis 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, pari- etal pericardium; or tumor in the main bronchus less than 2 cm distal to
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1 Highest medistinal 2 Upper paratracheal 3 Prevascular and retrotracheal 4 Lower paratracheal
N1 nodes:
10 Hilar 11 Interlobar 12 Lobar nodes bronchi 13 Segmental 14 Subsegmental
A
Azygus v.
Inferior pulmonary ligament
Ligamentum arteriosum PA
PA Ao
B
3a
6
5 3p
1R 2R 4R
10 10 11
11 12 11
11 13 12
13 13
14 13
14
14 14
14 4L 7 8
9 9
2L 1L
5 Subaortic 6 Para-aortic 7 Subcarinal 8 Paraesophageal 9 Pulmonary ligament N2 nodes:
Ao Brachiocephalic
(innominate) a.
FIGURE 19.2. Lymph node maps of the lung.
T1 T1
£3 cm
£3 cm
FIGURE 19.3. Two views of T1 showing tumor 3 cm or less in greatest dimension.
T2 T2
T2 T2
Atelectasis or obstructive pneumonia
>3 cm
≥2 cm
≥2 cm
FIGURE 19.4. T2 is defined as a tumor with any of the following features of size or extent: more than 3 cm in greatest dimension; involving main bronchus, 2 cm or more distal to the carina; invades the visceral pleura; associated with atelectasis or obstructive pneumonitis that extends to the hilar region but does not involve the entire lung.
the carina, but without involvement of the carina; or associated atelecta- sis or obstructive pneumonitis of the entire lung (Figure 19.5)
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(2) (Figures 19.6A–E)
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T3 T3
T3 T3
£2 cm
Atelectasis or obstructive pneumonia of the entire lung
Pleural effusion with negative cytology
FIGURE 19.5. T3 is defined as a 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 2 cm distal to the carina, but without involvement of the carina; or associated atelectasis or obstructive pneumonitis of the entire lung.
T4
Great vessels
Heart
A
FIGURE 19.6. A. Tumor invasion of the heart and great vessels.
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 (Figure 19.7)
N2 Metastasis to ipsilateral mediastinal and/or subcarinal lymph nodes(s) (Figure 19.8)
N3 Metastasis to contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s) (Figure 19.9)
T4
Heart Superior
vena cava
B T4
Aorta
Esophagus Vertebral body
C
FIGURE 19.6. B. Tumor invasion of the superior vena cava and heart. C. Tumor invasion of the aorta, esophagus, and vertebral body.
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T4 M1
Tumor nodule
Primary tumor
Primary tumor Separate tumor nodule
D
T4
Malignant pleural effusion
E
FIGURE 19.6. D. N1 is defined as a separate tumor nodule(s) in the same lobe. M1 is defined as a separate tumor nodule(s) in a different lobe (ipsilateral or
contralateral). E. Tumor with malignant pleural effusion (see note 2).
Distant Metastasis (M)
MX Distant metastasis cannot be assessed M0 No distant metastasis
M1 Distant metastasis present(3)(Figure 19.9)
N1 Peribronchial
N1 Hilar
FIGURE 19.7. N1 is defined as metastasis to ipsilateral peribronchial (left side of diagram) and/or ipsilateral hilar lymph nodes (right side of diagram), and intrapulmonary nodes including involvement by direct extension of the primary tumor.
N2
Ipsilateral mediastinal
N2 Subcarinal
FIGURE 19.8. N2 is defined as metastasis to ipsilateral mediastinal (right side of diagram) and/or subcarinal lymph nodes(s) (left side of diagram).
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M1 N3
N3
FIGURE 19.9. N3 is defined as metastasis to contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s) whereas M1 is defined as distant metastasis.
STAGE GROUPING
Occult carcinoma TX N0 M0
0 Tis N0 M0
IA T1 N0 M0
IB T2 N0 M0
IIA T1 N1 M0
IIB T2 N1 M0
T3 N0 M0
IIIA T1 N2 M0
T2 N2 M0
T3 N1 M0
T3 N2 M0
IIIB Any T N3 M0
T4 Any N M0
IV Any T Any N M1
NOTES
1. 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.
2. 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.
3. M1 includes separate tumor nodule(s) in a different lobe (ipsilateral or contralateral).
