Pancoast Tumour

In 1932, Pancoast defined a superior pulmonary sulcus tumor as a mass growing at the thoracic inlet that produces a constant and characteristic clinical presentation of pain in an eighth cervical or first and second thoracic trunk distribution.

Pancoast tumors are a subset of lung cancers that invades the apical chest wall. Because of their location in the pleural apex, they invade adjoining tissue. Although various other tumors may produce a similar clinical presentation because of their location at the thoracic inlet, the most common cause is generally believed to be a bronchogenic carcinoma arising in or near the superior sulcus and invading the adjacent extrathoracic structures by direct extension. The location of the tumor, rather than its pathology or histology of origin, is significant in producing its characteristic clinical pattern.

Carcinomas in the superior pulmonary sulcus produce Pancoast syndrome, thus causing pain in the shoulder and along the ulnar nerve distribution of the arm and hand. (These carcinomas also cause Horner syndrome.) These apical lung tumors tend to be locally invasive early. In the absence of metastases and regional nodal involvement, these apical cancers can be successfully treated.

Frequency:
Pancoast tumors are much less common than other lung cancers. In past series, the rate of Pancoast tumors varied from 1-3% of all lung cancers. A major issue with Pancoast tumors is the delay in diagnosis. The apical lung cancer may not be visualized on an initial chest radiograph, and, by the time the patient presents with symptoms, the tumor has almost always invaded nearby structures. In addition, the symptoms produced by the disorder can be mimicked by numerous neurological or musculoskeletal disorders, thus delaying diagnosis.

Etiology:
The risk factors for almost all lung cancers are similar. These include prior prolonged asbestos exposure, exposure to industrial elements (eg, gold, nickel), smoking, and secondary smoke exposure.

Pathophysiology:
The mass in the superior sulcus is an extension of a lung tumor; most of it lies outside the lung and involves the chest wall, nerve roots, lower trunks of the brachial plexus, sympathetic chain, stellate ganglion, ribs, and bone. Most Pancoast tumors are squamous cell carcinomas or adenocarcinomas. Only 3-5% are small cell carcinomas. Squamous cell carcinoma occurs more frequently, although large cell and undifferentiated types are also common. Adenocarcinoma is sometimes found in this location and can even be metastatic. Involvement of the phrenic or recurrent laryngeal nerve or superior vena cava obstruction is not representative of the classic Pancoast tumor.

Symptoms
The symptoms are typical of the location of the tumor in the superior sulcus or thoracic inlet adjacent to the eighth cervical nerve roots, the first and second thoracic trunk distribution, the sympathetic chain, and the stellate ganglion. Initially, localized pain occurs in the shoulder and vertebral border of the scapula. Pain may later extend along an ulnar nerve distribution of the arm to the elbow and, ultimately, to the ulnar surface of the forearm and to the small and ring fingers of the hand (C8). If the tumor extends to the sympathetic chain and stellate ganglion, Horner syndrome and anhidrosis develop on the ipsilateral side of the face and upper extremity. Pain is frequently relentless and unremitting, often requiring narcotics for relief. The patient usually supports the elbow of the affected arm in the hand of the opposite upper extremity to ease the tension on the shoulder and upper arm.

The hand muscles may become weak and atrophic, and the triceps reflex may be absent. The first or second rib or vertebrae may be involved by tumor extension and intensify the severity of pain. The spinal canal and spinal cord may be invaded or compressed, with subsequent symptoms of spinal cord tumor or cervical disk disease. Confusion with thoracic outlet syndrome and cervical disk disease is common in the early clinical course. Careful neurologic examination, electromyographic studies, and ulnar nerve studies are performed to verify the precise diagnosis.

Infrequently, a patient with a Pancoast tumor may also have features of a paraneoplastic syndrome. Most of the metabolic manifestations are the result of the secretion of endocrine chemicals by the tumor. Manifestations encompass Cushing syndrome, excessive antidiuretic hormone secretion, hypercalcemia, myopathies, hematological problems, and hypertrophic osteoarthropathy. The presence of paraneoplastic syndromes does not connote unresectability, but most of these are associated with small cell cancer.

 Imaging
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).

Chest Image

Axial MRI

Axial CT

Coronal MRI

Coronal CT

Differential diagnoses
Differential diagnoses of masses in the apical chest include primary tumors of the thyroid, larynx, and pleura. Other causes may include infectious disorders of the lung, aneurysms of the subclavian vessels, amyloid of pleura, and multiple myeloma. The differential diagnoses of arm and shoulder pain are extensive; however, primarily, thoracic outlet syndrome and cervical disk disease must be excluded.

Diagnosis
In the very rare patient, sputum cytology has been helpful. Initially, most Pancoast tumors are diagnosed histologically based on 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.

Liver, bone, and brain scans are performed to determine the presence of any metastatic disease. Although more than 90% of patients can be correctly diagnosed based on clinical and radiological findings alone, open biopsy of the tumor for pathological validation may be performed through a supraclavicular incision. Results from a needle biopsy through the supraclavicular or posterior triangle are also successful in confirming the diagnosis and in delineating the cell type prior to treatment. Even though clinical diagnosis is relatively simple, performing a tissue biopsy is still necessary.

Staging
Staging is determined by the location of the lesion and its metastases. The true Pancoast tumor is usually T3, which describes the extension of the tumor through the visceral pleura into the parietal pleura and the chest wall. Pancoast tumors are classified as T4 when mediastinal invasion, cervical invasion, or both have occurred. Peripheral metastases signal a poor prognosis, and surgery is contraindicated in such cases.

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 scan results 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.

Contraindications: Contraindications to surgery include (1) extensive invasion of the neck, brachial plexus, or vertebrae; (2) perinodal mediastinal extension; and (3) peripheral metastases. These include extrathoracic metastatic disease and positive mediastinal nodes. Complete upper and lower brachial plexus invasion is a relative contraindication, provided complete surgical excision can be performed. Vertebral body involvement should not be a contraindication unless invasion of the cortex is confirmed.

Patients with poor respiratory function and ischemic coronary artery disease need a proper workup prior to surgery. Heart failure, recent myocardial infarction, and unstable angina are contraindications for surgery. Although many patients are elderly (the age group with the highest risk of complications), age alone is relatively unimportant if the patient is in otherwise good health.

Contraindications to surgery can be summarized as follows:

• Extensive involvement of brachial plexus
• Involvement of paraspinal region
• Involvement of lamina of vertebrae body
• Involvement of mediastinal lymph node

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