Pancoast tumor overview

# Overview
A Pancoast tumor, also known as superior sulcus tumor,  defined primarily by its location at the pulmonary apex. The tumor can cause compression of a brachiocephalic vein, subclavian artery, phrenic nerve, recurrent laryngeal nerve, or, compression of a sympathetic ganglion.

# Historical Perspective
Pancoast tumor was first described by Hare in 1838. In 1924, Henry K. Pancoast discovered the association between apical chest tumors, characteristic pain distribution, and Horners syndrome. In 1954, external beam radiation was used for the treatment of associated pain by Haas and colleagues. In 1990s a combination of chemotherapy and radiotherapy was found to be associated with better prognosis and treatment outcome.

# Classification
The staging of the pancoast tumor is based on the TNM system. Pancoast tumors staging starts at T3  always, as there is an invasion of the chest wall. Invasion of the vertebral body or the subclavian vessels is regarded as T4.

# Pathophysiology
Pancoast tumor is the type of lung cancer that is associated with invasion of the apical chest wall. The location of Pancoast tumor in the superior sulcus results in an invasion of adjacent structures and in its characteristic clinical presentation. The progression of Pancoast tumor usually involves spread across the pleural apex to invade the following structures by direct extension into lymphatic vessels in the endothoracic fascia, intercoastal nerves, lower roots of brachial plexus, stellate ganglion, sympathetic chain, adjacent ribs, adjacent vertebra bodies, extension to the spinal cord can result in cord compression, subclavian artery or subclavian vein. The development of Pancoast syndrome is the result of tumors in the superior pulmonary sulcus is characterized by pain along ulnar nerve distribution and Horner's syndrome.

# Causes
Most common cause of Pancoast tumor is nonsmall cell lung carcinoma (NSCLC). Common types of non-small cell lung carcinoma (NSCLC)  presenting as Pancoast tumor are squamous cell cancer, adenocarcinoma and large cell carcinoma. Less common causes of Pancoast tumor includes small cell cancer as it rarely presents as a peripheral tumor. Pancoast syndrome is classically associated with Pancoast tumor. Rare causes of Pancoast syndrome include desmoid tumor, metastasis, hematologic neoplasms, and infections that may present as a tumor localized to the lung apex.

# Differential Diagnosis
Pancoast tumor must be differentiated from other causes of mass located in the apical region of the chest which may present with pain in the shoulder region. Differential diagnosis includes most common other conditions that cause hemoptysis, cough, dyspnea, wheeze, chest pain, shoulder pain, unexplained weight loss, unexplained loss of appetite, and fatigue such as superior vena cava syndrome, thoracic outlet syndrome, cervical disk disease, pneumonia/bronchitis, carcinoid tumor, infectious granuloma and thyroid mass.

# Epidemiology and Demographics
Pancoast tumors are a rare type of non-small cell lung cancers (NSCLC), account for fewer than 5% of all lung cancers. In the United States, the age-adjusted prevalence of pancoast tumor is estimated to be 5 per 100,000. The prevalence of lung cancer significantly increases among smokers and individuals with chronic exposure to risk factors for lung cancer. In 2014 the incidence of Pancoast tumor was approximately 3 cases per 100,000. Lung cancer is more common in older adults. It is rare in people under age 45. Males are thought to be more predisposed to the development of lung cancer. This gender discrepancy is often attributed to the historically increased rate of smoking among males compared to females. The male to female ratio for the incidence of lung cancer is approximately 1.4 to 1. There is no racial predilection for Pancoast tumor. The incidence of lung cancer is lower in developing countries than in developed countries. It is unknown whether this decreased incidence is due to decreased cancer rates or decreased detection rates. Western Europe and the U.S. have the highest incidence of lung cancer.

# Risk Factors
Common risk factors in the development of Pancoast tumor include asbestos exposure for prolonged period of time, exposure to gold, nickel, smoking, secondary smoke exposure.

# Screening
There is insufficient evidence to recommend routine screening for Pancoast tumor.

# Natural History, Complications and Prognosis
The patient experiences non-specific symptoms such as cough, hemoptysis, dyspnea, chest pain, dysphonia, dysphagia, lack of appetite, weight loss, and fatigue from 3 weeks to 3 months before seeking medical attention. Without treatment, the patient will develop initial symptoms of cough and chest pain, which may eventually lead to Pancoast syndrome. The symptoms of Pancoast syndrome start as referred pain to the shoulder. Without treatment, the tumor may invade surrounding tissues to cause pain along the ulnar nerve distribution, atrophy of hand muscles and spinal cord compression. The complications associated with Pancoast tumor are breathing difficulties, pneumonia, hemoptysis, pain, pleural effusion, metastasis, Horner's syndrome, superior vena cava syndrome, Compression of the spinal cord and paraplegia (paralysis of the lower half of the body with involvement of both legs) develop when the tumor extends into the intervertebral foramina (opening between two vertebrae). The prognosis of Pancoast tumor depends on the stage of the tumor at diagnosis. The presence of the following is associated with a poor prognosis among patients with Pancoast tumor includes Horner syndrome, spread to the mediastinal lymph nodes, incomplete resection of tumor, involvement of supraclavicular lymph node, vertebral body invasion, metastasis to the brain.

# Diagnosis

## Diagnostic study of choice
CT scan is the gold standard test for the diagnosis of Pancoast tumor. MRI imaging should be performed for evaluation of chest wall invasion, examination of vascular structures and brachial plexus involvement, evaluation of resectability of the tumor.

## History and Symptoms
The hallmark of Pancoast tumor is lung cancer located in the apex of the lung. A positive history of shoulder pain and atrophy of hand musculature, Horner's syndrome and forearm edema is suggestive of Pancoast Syndrome. The most common symptoms of Pancoast tumor include cough, hemoptysis, dyspnea, chest pain, lack of appetite, weight loss, fatigue, symptoms of Pancoast Syndrome resulting from Pancoast tumor include shoulder pain along the vertebral border of the scapula, Horner's syndrome and weakness of hand muscles. Less common symptoms of Pancoast syndrome include paraplegia.

## Physical Examination
Common physical examination findings of Pancoast tumor include decreased/absent breath sounds, pallor, low-grade fever, and tachypnea. On physical examination, Pancoast tumor may present with features of lethargy, emaciation, confusion, low-grade fever, decreased SPO2, tachypnea, tachycardia, low BP, decreased/absent breath sounds, bone pain, fractures (usually in the vertebrae, femur, pelvic bones, and the ribs), pallor, decreased sweating on ipsilateral side of the face, ptosis, miosis, anhydrosis, supraclavicular lymphadenopathy, cranial nerve palsies, tingling and pain along the distribution of ulnar nerve, clubbing of fingers, weakness of arms and hands, hemiplegia, paraplegia, shoulder pain, edematous swelling of the ipsilateral arm.

## Laboratory Tests
Pancoast tumor is a subtype of lung cancer located at the lung apex. There are no characteristic diagnostic lab findings associated with Pancoast tumor. The laboratory findings associated with lung cancer are the following neutropenia, hyponatremia, hypokalemia, hypercalcemia, respiratory acidosis, hypercarbia, hypoxia, and tumor cells in sputum and pleural effusion cytology. There are no ECG findings associated with Pancoast tumor.

## Electrocardiogram
There are no ECG findings associated with Pancoast tumor.

## Chest X-ray
An x-ray may be helpful in the diagnosis of Pancoast tumor. Lordotic view on x-ray is helpful in visualizing Pancoast tumor because of its characteristic location in the apical portion of the lung. Findings on an x-ray suggestive of Pancoast tumor include opacity at the apex of the lung or in the superior sulcus area, the spread of the tumor can result in rib invasion that is observed as a bone destruction of posterior ribs, vertebral body infiltration, enlargement of the mediastinum.

## CT scan
CT scan is diagnostic of Pancoast tumor. CT scan has a limited ability to determine the extent of invasion of the primary tumor into adjoining structures when compared to MRI scan. Findings on CT scan of the chest suggestive of Pancoast tumor include invasion of brachial plexus, invasion of the chest wall and/or mediastinum, the extension of the tumor into vena cava, trachea and esophagus, subclavian-vessel involvement is assessed by contrast CT scanning.

## MRI
MRI is helpful in the diagnosis of Pancoast tumor. MRI offers greater detail in the evaluation of chest wall invasion, examination of vascular structures and brachial plexus involvement and resectability of the tumor.

## Ultrasound
On endobronchial and endoscopic ultrasound, characteristic findings of lung cancer may include: enlarged lymph nodes and local invasion to adjacent bronchial structures and mediastinum. Endobronchial ultrasound is a first-line diagnostic modality for mediastinal staging.

## Other Imaging Findings
A bone scan may demonstrate bone metastases. FDG(18 F fluoro deoxyglucose) PET scans along with contrast enhanced CT may be helpful in the diagnosis of extent of Pancoast tumor.

## Other Diagnostic Studies
A bone scan may demonstrate bone metastases. FDG(18 F fluorodeoxyglucose) PET scans along with contrast enhanced CT may be helpful in the diagnosis of the extent of Pancoast tumor. Other diagnostic studies for evaluating the spread of Pancoast tumor include bone scintigraphy, PET scan, molecular tests, and biopsy.

# Treatment
The optimal management approach of Pancoast tumor depends on a series of characteristics, that include pre-treatment evaluation, location, and adequate staging. Common treatment options for management include radiation therapy alone, radiation therapy and surgery, concurrent chemotherapy with radiation therapy and surgery, surgery alone (for selected patients).

### Medical Therapy
Chemotherapeutic regimens are based on platinum agents such as cisplatin, carboplatin, oxaliplatin, and satraplatin. Alternative regimens include paclitaxel, gemcitabine, or etoposide. Chemotherapeutic regimens are adjusted based on individual characteristics and body surface. The regimen adjustment according to tumor evolution has demonstrated longer survival rates, optimal symptom control, and higher quality of life.

### Surgery
Surgery is the mainstay of therapy for early-stage Pancoast tumor. Surgical procedure selection will depend on the histology, margins, and size of the tumor. Common surgical procedures for the treatment of Pancoast tumor, include lung resection with lobectomy, lung resection with pneumonectomy with or without lymph node dissection, thoracotomy with the removal of the entire lung or lobe (lobectomy) along with regional lymph nodes (peribronchial and perihilar lymph node dissection) and pathological evaluation. If evidence of lymph node extension of the disease is present adjuvant chemotherapy should be administered. Surgical resection is not recommended for patients with advanced or metastatic lung carcinoma. Surgical staging of the mediastinum is considered standard if accurate evaluation of the nodal status is needed to determine therapy. Surgical treatment consists of a thoracotomy with removal of the entire lung or lobe along with regional lymph nodes and contiguous structures. Pneumonectomy is used if the tumor involves the main bronchus, extends across a fissure or is located such that wide excision is required. Survival following curative resection is approximately 30% at 5 years and 15% at 10 years. The best results are found in squamous cell carcinoma followed by large-cell carcinoma and the adenocarcinoma. If the tumor is inoperable, stereotactic ablative radiation therapy should be administered.

## Primary Prevention
Pancoast tumor is a subtype of lung cancer localized to the lung apex. Effective measures for the primary prevention of lung cancer include smoking cessation and avoidance of second-hand smoking. Lifestyle changes, such as a healthy diet rich with fruits and vegetables and regular exercise, might decrease the risk of developing cancer in general.

## Secondary Prevention
Secondary prevention for lung cancer consists of smoking cessation and screening. Secondary chemoprevention focuses on blocking the development of lung cancer in individuals in whom a precancerous lesion has been detected.