Approach Considerations
Imaging and biopsy are the cornerstones of evaluation of Pancoast syndrome. The apex of the lung can be difficult to investigate because it is bounded laterally by the first rib, posteriorly by the first rib and the vertebral bodies, and anteriorly by the costal cartilage of the first rib and the manubrium. Plain radiographs of the chest frequently show no change or an asymmetry or thickening of the apical cap. Apical lordotic films may be more revealing. Computed tomography (CT) and magnetic resonance imaging (MRI) have become standard. Liver, bone, and brain scans are performed to look for metastatic disease.
In very rare cases, sputum cytology has been helpful. Initially, most Pancoast tumors are diagnosed histologically on the basis of transthoracic needle biopsy results. Diagnosis via bronchoscopy is less helpful because most of these tumors are peripherally located. The flexible scope is more useful than the rigid scope in obtaining bronchoscopic aspirates and brush biopsy specimens.
Although more than 90% of patients can be correctly diagnosed on the basis of clinical and radiologic findings alone, open biopsy for pathologic validation may be performed through a supraclavicular incision. Results from a needle biopsy through the supraclavicular or posterior triangle can also be successful in confirming the diagnosis and in delineating the cell type before treatment. Even though clinical diagnosis is relatively simple, performing a tissue biopsy is still necessary.
Laboratory Studies
The blood workup for patients with Pancoast tumors is not specific, and results are not diagnostic.
Lung cancers produce various substances. Elevated levels of oncofetal carcinoembryonic antigen and beta-2 microglobulins are associated with many lung cancers. Unfortunately, these findings are not diagnostic, because levels of these chemicals are also elevated by other nonspecific causes, such as smoking and bronchitis.
Tumor markers (eg, bombesin, neuron-specific enolase, and other peptides) are common with small cell cancers and are related to the stage of the disease. They may aid in distinguishing differentiated forms of lung cancer from undifferentiated forms.
Various tumor oncogenes, including K-ras, c-myc, TP53, and HER-2/neu, have also been identified in patients with lung cancers. Although the presence of these oncogenes has some prognostic value, they are not important for staging of the cancer.
Routine blood work in all patients with a lung cancer includes a complete blood cell count (CBC), blood urea nitrogen (BUN) and creatinine levels, and urinalysis. Measurement of coagulation parameters, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT), is appropriate. Unless metastatic disease is evident, liver function tests are not regularly performed. Any patient deemed a surgical candidate has blood drawn for typing and crossmatching.
Urinalysis is performed in all patients before surgery. A catheter specimen is obtained in women if the initial urinalysis result suggests contamination.
CT, MRI, and PET
CT and MRI of the neck, chest, and upper abdomen have largely replaced older radiographic studies in the workup of Pancoast syndrome.
CT is less expensive than MRI and much more available. It can help assess bone destruction and is useful in general imaging of the lung for the evaluation of mediastinal adenopathy, other pulmonary nodules, and liver involvement. CT scanning helps identify invasion of the brachial plexus, chest wall, and mediastinum, as well as reveal involvement of the vena cava, trachea, and esophagus. Contrast CT scanning is useful for assessing subclavian vessel involvement.
MRI is useful for evaluating resectability. It may be more accurate in evaluating chest wall invasion, examining vascular structures, and assessing the brachial plexus for invasion. [29, 30, 31] It is more accurate than CT for assessing invasion of cervical structures and vertebral bodies.
MRI has no advantage over CT in the evaluation of the mediastinum. In fact, CT is much better than MRI for assessing the mediastinum for lymph node involvement. Rib or transverse process involvement is not a sign of inoperability; however, involvement of the vertebral body makes achieving an adequate margin of resection very difficult and reduces the odds for survival.
MRI of the vertebrae may help differentiate between tumor invasion and reactive inflammation in patients with Pancoast syndrome, and thus help avoid unnecessary vertebrectomy. A retrospective study of MRI signal intensity characteristics in 92 vertebrectomies found that the optimum cut-offs (P < 0.05) to distinguish invasion from reactive inflammatory changes were as follows [32] :
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Contrast-to-noise ratio (CNR) > 11 for the T2-weighted fat-sat sequence (sensitivity 100%)
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CNR > 9 for contrast-enhanced T1-weighted fat-suppressed sequence (sensitivity 100%)
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CNR < -30 for the T1-weighted sequence (specificity 97%)
Additional staging studies should be considered. Mediastinoscopy should be performed to evaluate mediastinal nodes. The presence of N2 mediastinal lymphadenopathy has a significant adverse effect on survival. CT or MRI of the head to exclude occult metastasis should be performed if treatment with curative intent is planned. CT of the chest can be extended to include the liver and adrenal glands.
Positron-emission tomography (PET) scanning is approved by the US Food and Drug Administration for the staging of non–small cell lung cancer in general, and it is increasingly being used in the setting of Pancoast syndrome.
Chest Radiography
Chest radiographs may reveal a small homogenous apical cap or pleural thickening; they may show a thin plaque at the lung apex in the area of the superior sulcus or may reveal a large mass, depending on the stage of the tumor. Suggestive films should prompt the astute diagnostician to order apical lordotic views for better visualization of the area.
Bone destruction of the posterior 1-3 ribs may sometimes be apparent. Rib invasion or vertebral body infiltration may be evident on a plain chest radiograph. Mediastinal enlargement may be apparent.
Bronchoscopy and Biopsy
Bronchoscopy helps evaluate the tracheal and bronchial lumens; however, because most Pancoast tumors are peripheral, the diagnostic yield is low. Fiberoptic bronchoscopy has a higher yield than sputum cytology, which has positive results in fewer than 15% of patients, [33] but bronchoscopy findings are positive in only 20-30% of patients, because of the peripheral location of the tumor. [34] Bronchoscopy, however, can be useful in excluding otherwise unsuspected concurrent endobronchial lesions.
Tissue diagnosis is obtained on the basis of results from percutaneous needle biopsy, performed under either fluoroscopy or CT guidance. Staging is based on results of scalene node biopsy from palpable nodes or mediastinoscopy findings. If a patient presents with supraclavicular lymph node enlargement, then a fine-needle aspiration (FNA) biopsy of enlarged supraclavicular lymph nodes or an ipsilateral supraclavicular fullness procedure is a fast, safe, and inexpensive means of confirming the diagnosis.
Transthoracic needle biopsy by CT guidance has a high yield, up to 95% in some series. [35, 33, 36] Some tumors may be evaluated only by thoracotomy, either open or video assisted.
Other Tests
Rarely, arterial or venous involvement of the subclavian artery or vein occurs; thus, arteriography or phlebography may be helpful. This is usually accomplished in a retrograde fashion, although it can be approached from the opposite extremity or from the leg.
Baseline electrocardiography (ECG) is performed on all patients for comparison to postoperative ECG tracings (if one is performed).
Staging
Pancoast tumors are staged using the tumor-node-metastasis (TNM) system of the International System for Staging Lung Cancer, adopted by the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer (UICC). [37] This classification stages lung cancers in terms of tumor characteristics and tumor distribution.
The T designation describes the size and invasiveness of the primary tumor. T3 indicates a tumor of any size that invades the chest wall (the parietal pleura). T4 is a tumor of any size that invades the vertebral body, a neural or vascular structure, the mediastinum, the esophagus, or the trachea.
The N designation describes the distribution of positive lymph nodes. N1 indicates metastasis to ipsilateral peribronchial or hilar nodes. N2 indicates the spread to ipsilateral mediastinal or subcarinal nodes. N3 indicates metastasis to nodes of the contralateral hilar and mediastinal areas or to scalene or supraclavicular nodes, either ipsilateral or contralateral.
The M designation describes the extent of distant metastasis. M0 indicates no identifiable metastatic disease, and M1 designates the presence of distant metastasis (eg, to brain, bone, or liver). Any M1 findings indicate stage IV disease.
Staging is determined by the location of the lesion and its metastases. A true Pancoast tumor is usually T3, reflecting extension of the tumor through the visceral pleura into the parietal pleura and the chest wall; it is classified as T4 when mediastinal invasion, cervical invasion, or both have occurred (see the Table below). Peripheral metastases signal a poor prognosis, and surgery is contraindicated in such cases.
IIIB
Table. AJCC/UICC Stages for Pancoast Tumors. (Open Table in a new window)
Stage |
T(Tumor) |
N (Nodes) |
IIB |
T3 |
N0 |
IIIA |
T3 |
N1 |
IIIB |
T3 |
N2 |
IIIC |
T3, T4 |
N3 |
Mediastinoscopy is used for staging to delineate the metastases to mediastinal lymph nodes. Cervical mediastinoscopy is indicated for right pulmonary lesions; a Chamberlain procedure (left second interspace mediastinoscopy) is indicated for left pulmonary lesions. Generally, mediastinoscopy is performed if the lymph nodes appear larger than 1 cm in diameter on a CT scan because the accuracy of CT for predicting metastatic involvement in enlarged lymph nodes is only 70%.
Conversely, if the CT scan does not reveal any enlarged lymph nodes, the patient is deemed operable. If the nodes in the mediastinum are positive, the prognosis is poor. The exception to this rule is an upper-lobe lesion with positive nodes on the right side of the trachea only. If these are internodal, spread is considered local, and the tumor may still be resectable.
Attar et al, reviewing their experience with 105 patients treated from 1955 to 1997, found that 30% of patients presented with T3 N0 disease (stage IIB), 26% with T4 N0 (stage IIIA), and 25% with metastatic disease (M1, stage IV). [22] In their review of 124 patients, Ginsberg et al found that 58% of patients had T3 N0 disease, 16% had T3 N2, and only 1% had T3 N1; in addition, 6% of patients had T3 N3 disease, 18% had T4 N0, and 1% had T4 N. [20]
Tables
Stage |
T(Tumor) |
N (Nodes) |
IIB |
T3 |
N0 |
IIIA |
T3 |
N1 |
IIIB |
T3 |
N2 |
IIIC |
T3, T4 |
N3 |
