What is the tumor in the upper lung that causes sympathetic nerve activation?

Pancoast Tumor: The Upper Lung Tumor That Causes Sympathetic Nerve Activation

Pancoast tumor (also called superior sulcus tumor) is the tumor in the upper lung that causes sympathetic nerve activation, resulting in Horner's syndrome through infiltration of the sympathetic chain and stellate ganglion. 1, 2

Clinical Characteristics

Pancoast tumors are defined as lung cancers arising in the apex of the lung that involve structures of the apical chest wall. They have specific diagnostic criteria:

• Located at the apex of the lung
• Involve apical chest wall structures at the level of the first rib or above
• Frequently invade the brachial plexus, subclavian vessels, or spine 1

Sympathetic Nerve Involvement

The hallmark feature of Pancoast tumors is their ability to cause sympathetic nerve dysfunction through:

• Infiltration of the sympathetic chain and stellate ganglion
• This infiltration results in Horner's syndrome, characterized by:
  • Ptosis (drooping eyelid)
  • Miosis (constricted pupil)
  • Anhidrosis (lack of facial sweating) on the affected side 1, 2

Pancoast Syndrome

The complete Pancoast syndrome consists of:

• Shoulder and arm pain from invasion of the brachial plexus and adjacent tissues
• Horner's syndrome from infiltration of the sympathetic chain and stellate ganglion
• Weakness, pain, and paresthesias in the distribution of C8, T1, and T2 nerve roots 1

Pathology

Most Pancoast tumors are non-small cell lung cancers:

• Approximately 2/3 are adenocarcinomas
• The remainder are squamous cell and large cell carcinomas 3
• They account for less than 5% of all bronchogenic carcinomas 3, 4

Staging and Classification

• Pancoast tumors are classified as T3 if they involve the T1 or T2 nerve roots or first rib
• They are classified as T4 if there is involvement of C8 or higher nerve roots, brachial plexus cords, subclavian vessels, vertebral bodies, or lamina 1

Diagnosis

The diagnosis of a Pancoast tumor is based on:

1. Clinical presentation: Characteristic symptoms of Pancoast-Tobias syndrome
2. Radiographic findings: Mass or opacity in the apex of the lung infiltrating the first and/or second ribs
3. Tissue diagnosis: CT-guided fine needle aspiration/biopsy is preferred 3

Imaging

• CT scan and MRI provide excellent anatomic detail for small lesions
• MRI of the thoracic inlet is recommended to define the exact extent of tumor invasion before surgical intervention
• PET-CT is valuable for restaging tumors 5, 3

Treatment

The standard of care for potentially resectable Pancoast tumors is:

1. Induction chemoradiotherapy followed by
2. Surgical resection with the goal of complete tumor removal 3

Surgical approaches depend on tumor location:

• Anterior, middle, or posterior compartment of the thoracic inlet
• Depth and extent of invasion
• En bloc resection of invaded structures with pulmonary parenchyma resection (preferably upper lobectomy) 3

Prognosis

Prognosis depends on:

• T stage of tumor
• Response to preoperative chemoradiotherapy
• Completeness of resection

With modern treatment approaches:

• 2-year survival rate: 55-70%
• 5-year survival rate for complete (R0) resections: 54-77% 3

The main pattern of recurrence is distant metastases, particularly to the brain 3.

Clinical Pearls

• The distribution of symptoms, particularly pain outside the chest, may delay consideration of lung cancer as the primary etiology 1
• New-onset Horner's syndrome should always prompt a thorough investigation for malignancy, especially in adults with risk factors 2
• Invasion of the vertebral column is not a contraindication for surgery, but should be performed in oncologic centers with experience in spinal surgery 3

Pancoast tumors represent a unique subset of lung cancers that require specialized multidisciplinary management due to their complex anatomical involvement and characteristic sympathetic nerve activation.