Pancoast Tumor: Etiology, Pathophysiology, Clinical Features, Imaging, and Treatment

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Introduction

Pancoast tumors, also known as superior sulcus tumors, represent a unique subset of non-small cell lung cancers (NSCLCs) that arise in the lung apex. 

Although relatively rare, they are clinically significant due to their location and tendency to invade adjacent structures such as the brachial plexus, subclavian vessels, vertebrae, and sympathetic chain. 

As a result, they often present with striking neurological and musculoskeletal manifestations rather than the typical pulmonary symptoms, leading to delayed diagnosis.

This column provides a comprehensive review of the cause, etiology, pathophysiology, epidemiology, clinical features, imaging modalities, treatment strategies, and prognosis of Pancoast tumors, supplemented with case-based imaging examples. 

This knowledge is crucial for clinicians, radiologists, and oncologists aiming to improve early recognition and optimize patient outcomes.

Case Presentation

A 74-year-old male presented with persistent left shoulder pain radiating to the axilla and proximal left upper limb. 

Clinical suspicion initially leaned toward degenerative cervical spine disease. However, multimodal imaging revealed a Pancoast tumor at the left lung apex.

Figure 1: Cervical spine radiograph demonstrated multilevel degenerative changes with disc height loss and osteophytes, but no acute soft tissue swelling.

Figure 2: Cervical spine and brachial plexus MRI revealed a left apical lung mass invading the T1 nerve root.

[Figure 3] CT axial post-contrast (lung window) showing irregular apical mass.

[Figure 4] CT axial post-contrast (soft tissue window) highlighting pleural invasion.

Figures 3 & 4: Contrast-enhanced CT of the chest confirmed a 2.6 cm irregular nodular lesion in the left lung apex, encroaching on the pleura and intercostal space.

Figure 5: PET/CT demonstrated FDG uptake at the apical lesion without mediastinal lymphadenopathy or distant metastasis.

The final diagnosis was Pancoast tumor (superior sulcus tumor).

Etiology and Pathogenesis

Pancoast tumors are predominantly non-small cell lung carcinomas (NSCLC).

  • Historically, squamous cell carcinoma was the most common subtype.

  • More recently, adenocarcinoma has become the predominant histology due to shifting global lung cancer epidemiology.

  • Rarely, metastases, lymphomas, sarcomas, or even infectious processes (tuberculosis, fungal infections) may mimic a Pancoast tumor.

The apical location predisposes these tumors to invade adjacent structures:

  • Brachial plexus → severe shoulder/arm pain, muscle weakness, paresthesia.

  • Stellate ganglion → Horner’s syndrome (ptosis, miosis, anhidrosis).

  • Subclavian vessels → upper limb vascular insufficiency.

  • Ribs and vertebrae → bony destruction, radiculopathy.

Pathophysiology

The superior sulcus of the lung is a confined anatomical region bounded by the first rib, vertebrae, and clavicle. Even small tumors in this space can produce severe clinical symptoms. The infiltration of:

  • C8–T2 nerve roots → characteristic Pancoast-Tobias syndrome.

  • Sympathetic chain → Horner’s syndrome.

  • Vertebral column → spinal cord compression.

Epidemiology

  • Pancoast tumors account for 3–5% of all lung cancers.

  • In the U.S., with ~200,000 new lung cancer cases annually, about 6,000–10,000 cases are Pancoast tumors.

  • Strongly associated with smoking history.

  • Peak incidence: 6th to 7th decade of life.

  • Slight male predominance.

Clinical Presentation

Unlike central lung cancers, pulmonary symptoms (cough, hemoptysis, dyspnea) are often absent early. Instead, Pancoast tumors manifest through neurological and musculoskeletal signs:

  • Shoulder pain (initial and most common symptom, >90% of patients).

  • Arm pain and paresthesia along the ulnar nerve distribution (C8–T1).

  • Muscle weakness and atrophy of intrinsic hand muscles.

  • Horner’s syndrome in 15–50% of cases.

  • Bony involvement → rib/vertebral destruction visible on imaging.

This atypical presentation often leads to misdiagnosis as cervical radiculopathy or orthopedic disease, delaying detection.

Imaging Features

  1. Chest X-ray: May show apical opacity or rib destruction. Often subtle in early disease.

  2. CT Chest: Gold standard for assessing bony involvement and tumor morphology.

  3. MRI: Superior for defining soft tissue and neurovascular invasion, especially brachial plexus and subclavian vessels.

  4. PET/CT: Essential for staging, excluding mediastinal nodal disease and distant metastases.

    • Absolute contraindications to surgery include:

      • Contralateral mediastinal nodal disease (N2/N3).

      • Distant metastasis. 

      • 50% vertebral body invasion.

      • Brachial plexus involvement above T1.

Treatment

Treatment depends on tumor stage and resectability:

  1. Induction chemoradiotherapy (CRT): Current standard for resectable disease.

    • Platinum-based chemotherapy + concurrent radiotherapy.

    • Improves local control and facilitates complete resection.

  2. Surgical resection: En bloc resection of the upper lobe with involved structures.

    • Posterior thoracotomy or combined approaches may be required.

    • Complete resection remains the strongest prognostic factor.

  3. Unresectable disease: Definitive chemoradiotherapy ± immunotherapy.

  4. Adjuvant therapy: Depending on nodal status and margin positivity.

Prognosis

  • Historically dismal prognosis (<5% survival).

  • With multimodal therapy, 5-year survival is now 30–60% in selected patients.

  • Prognosis depends on:

    • Completeness of resection.

    • Nodal involvement.

    • Absence of distant metastasis.

    • Patient performance status.

Quiz Section

Quiz 1: What is the most common initial symptom of a Pancoast tumor?

(A) Chronic cough

(B) Hemoptysis

(C) Shoulder pain

(D) Dyspnea

Quiz 2: Which structure’s invasion produces Horner’s syndrome in Pancoast tumors?

(A) Subclavian artery

(B) Stellate ganglion

(C) Vertebral body

(D) Brachial plexus

Quiz 3: Which imaging modality is most useful to evaluate brachial plexus involvement?

(A) Chest X-ray

(B) CT

(C) MRI

(D) Ultrasound

Quiz 4: Which is an absolute contraindication for surgical resection?

(A) Ipsilateral rib invasion

(B) Brachial plexus involvement above T1

(C) Pleural invasion

(D) Vertebral erosion <25%

Quiz 5: What is the approximate 5-year survival rate with complete resection following induction chemoradiation?

(A) <10% 

(B) 10–20%

(C) 30–60%

(D) >70%

Answer & Explanation

1. Answer: (C) Shoulder pain. Explanation: Apical invasion of the brachial plexus leads to severe shoulder pain, preceding pulmonary symptoms.

2. Answer: (B) Stellate ganglion. Explanation: Disruption of the sympathetic chain results in ptosis, miosis, and anhidrosis.

3. Answer: (C) MRI. Explanation: MRI provides superior soft-tissue contrast to assess nerve involvement.

4. Answer: (B) Brachial plexus involvement above T1. Explanation: This makes surgical resection technically unfeasible.

5. Answer: (C) 30–60%. Explanation: Modern multimodal therapy significantly improves prognosis.

Conclusion

Pancoast tumors, though rare, present unique diagnostic and therapeutic challenges due to their apical location and involvement of vital neurovascular structures. Early suspicion in patients with unexplained shoulder/arm pain, combined with appropriate imaging, is critical for timely diagnosis. Multimodal therapy, incorporating chemoradiation and surgery, offers the best chance for long-term survival. Clinicians should remain vigilant for this entity to avoid diagnostic delays and optimize patient care.

References

[1] G. Marulli, L. Battistella, M. Mammana, F. Calabrese, and F. Rea, “Superior sulcus tumors (Pancoast tumors),” Annals of Translational Medicine, vol. 4, no. 12, p. 239, 2016.
[2] V. D. Palumbo, S. Fazzotta, F. Fatica, et al., “Pancoast tumour: current therapeutic options,” Clin Ter.., vol. 170, no. 4, pp. e291-e294, 2019.
[3] K. Zarogoulidis, K. Porpodis, K. Domvri, E. Eleftheriadou, D. Ioannidou, and P. Zarogoulidis, “Diagnosing and treating pancoast tumors,” Expert Review of Respiratory Medicine, vol. 10, no. 12, pp. 1255–1258, 2016.
[4] V. D. Villgran, R. K. Chakraborty, and S. V. Cherian, “Pancoast Syndrome,” in StatPearls, Treasure Island, FL: StatPearls Publishing, 2020.
[5] J. A. Roth, “Management of Pancoast tumors,” Chest Surgery Clinics of North America, vol. 12, no. 1, pp. 107–126, 2002.
[6] R. K. Ginsberg et al., “Role of combined modality therapy in the management of superior sulcus tumors,” J Clin Oncol., vol. 7, no. 3, pp. 333–339, 1989.
[7] W. M. Mountain, “Staging of lung cancer: Revisions in the International System,” Chest, vol. 111, no. 6, pp. 1710–1717, 1997.

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