Which lymph node stations should be sampled during Endobronchial Ultrasound (EBUS) for lung cancer staging?

Lymph Node Stations to Sample During EBUS for Lung Cancer Staging

For optimal lung cancer staging, EBUS should sample at least three different mediastinal nodal stations (4R, 4L, and 7), with additional sampling of any abnormal lymph nodes identified by size (>10mm) or FDG-avidity on PET. 1

Recommended Lymph Node Stations for EBUS Sampling

Primary Stations (Required)

• Station 4R: Right lower paratracheal nodes
• Station 4L: Left lower paratracheal nodes
• Station 7: Subcarinal nodes

Additional Stations Based on Imaging Findings

• Station 2R/2L: Upper paratracheal nodes (if accessible and abnormal)
• Station 10: Hilar nodes (particularly if enlarged or FDG-avid)
• Station 11-12: Intrapulmonary nodes (if abnormal)

Sampling Strategy Based on Clinical Scenario

Abnormal Mediastinum on CT/PET

When CT or PET shows abnormal mediastinal nodes (>10mm or FDG-avid):

• Complete assessment of all mediastinal and hilar nodal stations
• Minimum sampling of three different mediastinal stations (4R, 4L, 7)
• Target all suspicious nodes identified by imaging 1

Normal Mediastinum with Risk Factors

For peripheral lung cancer with normal mediastinum but with:

1. Enlarged/FDG-avid ipsilateral hilar nodes
2. Primary tumor without FDG uptake
3. Tumor size ≥3 cm

EBUS-TBNA should sample:

• Stations 4R, 4L, 7 (minimum)
• Any hilar nodes (station 10) that appear abnormal 1

Centrally Located Tumors

For centrally located tumors without apparent mediastinal involvement:

• Systematic sampling of stations 4R, 4L, 7
• Additional sampling of hilar nodes (station 10) 1

Combined Approach Considerations

The combination of EBUS-TBNA and EUS-(B)-FNA provides more complete mediastinal staging than either technique alone:

• EBUS-TBNA can access stations 2L, 2R, 4L, 4R, 7,10,11, and 12
• EUS-(B)-FNA can better access stations 2L, 4L, 7,8, and 9
• Combined approach increases sensitivity by 13% over EBUS-TBNA alone 1

Stations Not Accessible by EBUS

• Stations 5 and 6 (aortopulmonary window) are generally not accessible via EBUS-TBNA alone and may require surgical approaches like VATS 2

Practical Considerations

Sampling Technique

• Obtain at least two satisfactory specimens from each target site 2
• Rapid on-site evaluation (ROSE) improves diagnostic yield 2
• For abnormal nodes, target those with ultrasound features suggesting malignancy:
  • Heterogeneous pattern (best predictor)
  • Round shape
  • Distinct margin
  • Absence of central hilar structure
  • High blood flow 3

Common Pitfalls

1. Incomplete sampling: Failing to sample the minimum three stations can lead to understaging
2. Missing N3 disease: Always sample contralateral nodes if abnormal before sampling N2 nodes
3. Relying solely on size criteria: Small nodes can harbor metastases; use ultrasound features to guide sampling
4. Inadequate specimens: Ensure proper technique to obtain sufficient material for diagnosis

Special Situations

Restaging After Neoadjuvant Therapy

• EBUS-TBNA should sample previously positive nodal stations
• Negative results require confirmation with surgical staging 1

When EBUS Alone Is Insufficient

• Consider adding EUS-(B)-FNA for more complete staging
• Surgical staging (mediastinoscopy) is recommended when endosonography is negative but clinical suspicion remains high 1

EBUS-TBNA has demonstrated superior sensitivity (92.3%) compared to CT (76.9%) and PET (80.0%) for mediastinal and hilar lymph node staging, with excellent specificity (100%) and diagnostic accuracy (98.0%) 4, making systematic sampling of the recommended stations crucial for accurate staging.