Background: Pancoast tumors are neoplasms of pulmonary origin located at the apical pleuropulmonary groove (superior sulcus). By direct extension, they typically involve the lower trunks of the brachial plexus, intercostal nerves, stellate ganglion, adjacent ribs, and vertebrae.

Pathophysiology: More than 95% of Pancoast tumors are non–small cell carcinomas, most commonly squamous cell carcinomas (52%) or adenocarcinomas and large cell carcinomas (approximately 23% for each subtype). Small cell carcinomas are seen in fewer than 5% of cases.

Staging of Pancoast tumor involves the tumor, node, and metastasis (TNM) classification in which T indicates site and size of the primary tumor, N is related to nodal involvement according to site, and M indicates the presence or absence of distant metastasis. These tumors are, at a minimum, T3N0M0 (T3 for chest wall invasion, stage IIB), and they are considered T4 lesions if the brachial plexus, mediastinal structures, or vertebral bodies are involved at the time of presentation. When supraclavicular nodes are involved, they are designated as N3 nodes, although they may be the first nodal station involved. Metastatic tumor in the ipsilateral nonprimary-tumor lobe of the lung or metastases to other organ systems is considered M1.

Frequency:

• In the US: Fewer than 5% of all primary lung cancers are located in the superior sulcus.

Mortality/Morbidity: Predictors of 5-year survival are weight loss, supraclavicular fossa or vertebral body involvement, stage of the disease and surgical treatment. A recent study by an M.D. Anderson group reported the following findings:

• Five-year survival for patients with stage IIB disease is 47%, compared with 14% in those with stage IIIA disease and 16% in those with stage IIIB disease.

• In patients with stage IIB disease, surgical treatment and weight loss are significant independent predictors of 5-year survival.
  
  
• Among patients with stage IIIA disease, the only predictor of survival is the Karnofsky performance score.
  
  
• In patients with stage IIIB disease, the only independent predictor of survival is a right superior sulcus location, which is associated with a 5-year survival rate that is worse than that of patients with tumors in the left superior sulcus.

• Compared with patients with squamous cell tumors, more patients with adenocarcinoma had cerebral metastases within 5 years.

Race: The differences among race are correlated with smoking prevalence. In white male smokers, the reported incidence of cancer of the lung is 15-30 times higher than that in nonsmokers. Since the early 1980s, the prevalence of tobacco use has decreased among white men but not among black men, and, as a result, lung cancer mortality rates in 1990 have been higher among black men than in white men.

Sex: Lung cancer is the leading cause of death in both men and women. The ratio of men to women is 2:1. To the authors' knowledge, no studies have shown any difference in prevalence in those with Pancoast tumors.

Age: Cancer of the lung in general occurs in individuals aged 40-70 years, with a peak incidence in those aged 50-70 years. Only 2% of all cases appear in persons younger than 40 years.

Anatomy: The tumor is located at the extreme apex of either the right or left lung, in what is called the pleuropulmonary groove or superior sulcus near the subclavian vessels. It frequently invades the second and third ribs, intercostal nerves, brachial plexus, stellate ganglion superiorly, and vertebral bodies posteriorly.

Clinical Details: The most common initial symptom is shoulder pain. This is usually due to tumor extension into any of these adjacent structures: brachial plexus, parietal pleura, endothoracic fascia, vertebral bodies, and first three ribs. Weakness, atrophy, and paresthesias of the hand, arm, and forearm are resultant symptoms. In as many as 25% of patients, compression of the spinal cord and paraplegia develop when the tumor extends into the intervertebral foramina.

Horner syndrome, which is described as ptosis, miosis, and anhidrosis, is reported to occur in 14-50% of patients. This is caused by invasion of the paravertebral sympathetic chain and stellate ganglion.

Less common manifestations include phrenic nerve and recurrent laryngeal nerve involvement. Superior vena cava (SVC) syndrome, which is compression of the SVC with resulting dyspnea and facial and upper extremity edema, is also uncommon.

Preferred Examination: Compared with other examinations, MRI is more accurate in identification of the extent of tumor involvement; it is superior to CT scanning in the detection of invasion of adjacent organs (eg, vertebral bodies, brachial plexus, subclavian vessels).

Histologic diagnosis is made in 95% of the cases by means of percutaneous transthoracic needle biopsy with fluoroscopic, ultrasonographic, or CT localization.

Among other considerations, CT or MRI of the brain is recommended in the initial evaluation, because distant metastases to the brain are not infrequent, and diagnosis of these is necessary for staging.

Limitations of Techniques: Noninvasive preoperative evaluation of the mediastinum with CT or MRI is limited by substantial false-positive and false-negative results (30-40%, depending on the criteria used to define enlarged lymph nodes and the patient population). Positron emission tomography (PET), and possibly surgical assessment of the mediastinum with lymph node sampling, should be strongly considered before curative surgery is attempted.

DIFFERENTIALS

Other Problems to be Considered:

Mesothelioma
Lymphoma
Plasmacytoma
Metastatic malignancies (thyroid, larynx)
Lymphomatoid granulomatosis
Cervical rib syndrome
Tuberculosis
Fungal infections

X-RAY

Findings: Posteroanterior (PA) chest radiographs show unilateral apical opacity or just asymmetry of the apices of greater than 5 mm. Local rib destruction can sometimes be observed. Lordotic chest views can be beneficial, but the findings can also be misleading.

Degree of Confidence: In the early stages, Pancoast tumors are difficult to detect on PA chest radiographs because of the difficulty in interpreting overlying shadows at the apices.