Lung Cancer Staging
In a patient with either a histologically-confirmed lung cancer or a pulmonary lesion suspected to be a lung cancer, assessment encompasses three areas: the primary tumor, presence of metastatic disease, and functional status (the patient's ability to tolerate a pulmonary resection). A discrete approach to these three areas allows the surgeon to systematically evaluate a patient, permits clinical stage assignment, and enables assessment of the patient's functional suitability for pulmonary resection.
Assessment of the primary tumor begins with the history and directed questions regarding the presence or absence of pulmonary, nonpulmonary, thoracic, and paraneoplastic symptoms. Patients often have already undergone a chest x-ray or CT scan before their initial visit with the surgeon; the location of the tumor can then help direct the history.
Obtaining a chest CT scan is the next stage in evaluating a new patient. A routine chest CT scan should include intravenous contrast material to enable delineation of mediastinal lymph nodes relative to normal mediastinal structures. Chest CT allows assessment of the primary tumor and its relationship to surrounding and contiguous structures. It also indicates whether invasion of contiguous structures has occurred.
The determination of invasion often is made by the patient's history and the location of the primary tumor. For example, a tumor abutting the chest wall with underlying rib destruction is clear evidence of local invasion. It is common to see the primary tumor abutting the chest wall without evidence of rib destruction. In this circumstance, the history is an accurate guide to the presence or absence of parietal pleural, rib, or intercostal nerve involvement. Similar observations apply to tumors abutting the recurrent laryngeal nerve, phrenic nerve, diaphragm, vertebral bodies, and chest apex. Thoracotomy should not be denied because of presumptive evidence of invasion of the chest wall, vertebral body, or mediastinal structures; proof of invasion may require thoracoscopy or even thoracotomy.
Distant metastases are found in about 40% of patients with newly diagnosed lung cancer. The presence of lymph node or systemic metastases may imply inoperability. A patient's risk of harboring metastatic disease must be carefully considered by the surgeon.
As with the primary tumor, assessment for the presence of metastatic disease should begin with the history and physical examination, focusing on the presence or absence of new bone pain, neurologic symptoms, and new skin lesions. In addition, constitutional symptoms (e.g., anorexia, malaise, and unintentional weight loss of greater than 5% of body weight) suggest either a large tumor burden or the presence of metastases. Physical examination should focus on the patient's overall appearance, noting any evidence of weight loss with muscle wasting. The appearance of cervical and supraclavicular lymph nodes as well as that of the oropharynx should also be examined for tobacco-associated tumors.
PET scanning has supplanted multiorgan scanning in the search for distant metastases to the liver, adrenal glands, and bones. Currently, chest CT and PET are routine in the evaluation of patients with lung cancer. Brain MRI should be performed when the suspicion or risk of brain metastases is increased. Several reports show that PET scanning appears to detect an additional 10 to 15% of distant metastases not detected by routine chest or abdominal CT and bone scans. The finding of PET FDG uptake at a distant site must be proven not to be a metastasis. This is often accomplished with MRI and/or biopsies.
Table 68-5 International Staging System for NSCLC, Seventh Edition
|Tx||Occult lung cancer|
|Primary tumor (T)|
|T1||Tumor ≤3 cm in diameter, surrounded by lung or visceral pleura, without invasion more proximal than lobar bronchus|
|T1a||Tumor ≤2 cm in diameter|
|T1b||Tumor >2 cm in diameter|
|T2||Tumor >3 cm but ≤7 cm, with any of the following features:|
|Involves main bronchus, ≥2 cm distal to carina|
|Invades visceral pleura|
|Associated with atelectasis or obstructive pneumonitis that extends to the hilar region but does not involve the entire lung|
|T2a||Tumor ≤5 cm|
|T2b||Tumor >5 cm|
|T3||Tumor >7 cm or any of the following:|
|Directly invades any of the following: chest
wall, diaphragm phrenic nerve, mediastinal pleura, parietal pericardium, main bronchus <2 cm from carina (without involvement of carina)
|Atelectasis or obstructive pneumonitis of the entire lung|
|Separate tumor nodules in the same lobe|
|T4||Tumor of any size that invades the mediastinum,
heart, great vessels, trachea, recurrent laryngeal
nerve, esophagus, vertebral body, or carina or
with separate tumor nodules in a different ipsilateral lobe
|Regional lymph nodes (N)|
|N0||No regional lymph node metastases|
|N1||Metastases in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension|
|N2||Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s)|
|N3||Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s)|
|Distant metastasis (M)|
|M0||No distant metastasis|
|M1a||Separate tumor nodule(s) in a contralateral lobe; tumor with pleural nodules or malignant pleural or pericardial effusion|
|M1b||Distant metastasis present (includes metastatic tumor nodules in a different lobe from the primary tumor)|
|Stage groupings of TNM subsets|
|Stage IV||Any T, any N, M1a or M1b|
From: Adult Chest Surgery, 2e, Overview of Anatomy and Pathophysiology of Lung Cancer. David J. Sugarbaker, MD, Raphael Bueno, MD, Yolonda L. Colson, MD, Michael T. Jaklitsch, MD, Mark J. Krasna, MD, Steven J. Mentzer, MD, Marcia Williams, Ann Adams
Board Review Questions
1. Which of the following is NOT a non-small-cell tumor of the lung?
A. Squamous cell carcinoma
B. Bronchoalveolar carcinoma
C. Large-cell carcinoma
D. Carcinoid tumor
2. The modified Chamberlain procedure is used to biopsy
A. Aortopulmonary window nodes
B. Paraesophageal nodes
C. Supradiaphragmatic periaortic nodes
D. Subcarinal nodes
3. A 65-year-old who has smoked 2 packs a day for 45 years is found to have a 2-cm solitary pulmonary nodule 1 cm from the surface of the superior segment of the right lower lobe. The best initial diagnostic procedure is
A. Observation with biopsy if this increases in size over 3-6
C. Fine-needle aspiration
D. Open thoracotomy for excisional biopsy
1. The correct answer is D. Carcinoid tumor
2. The correct answer is A. Aortopulmonary window nodes
3. The correct answer is C. Fine-needle aspiration