What is the initial workup for lesions above and below the diaphragm in metastatic cancer?

Initial Workup of Lesions Above and Below the Diaphragm for Metastatic Cancer

For patients with suspected metastatic cancer, a contrast-enhanced CT scan of the chest and upper abdomen should be the initial imaging study, followed by FDG PET/CT to evaluate for lesions above and below the diaphragm.

Initial Imaging Approach

Primary Imaging Studies

• Contrast-enhanced CT scan of the chest and upper abdomen is recommended as the initial imaging study for staging patients with suspected metastatic disease 1
• FDG PET/CT should be obtained for initial staging to evaluate lesions both above and below the diaphragm, as it can identify metastatic disease not seen on CT in approximately 10% of patients 1
• If abnormalities suggesting metastatic disease in the abdomen are observed on chest/upper abdomen CT or PET/CT, a dedicated abdominal (±pelvic) CT scan with IV and oral contrast should be performed 1

Supplementary Imaging

• MRI (preferably with IV contrast) may be obtained to further assess invasion of tumor into the diaphragm, chest wall, mediastinum, and other areas when CT findings are equivocal 1
• Brain MRI with contrast should be considered when evaluating for distant metastatic disease, particularly when neurological symptoms are present 1

Invasive Diagnostic Procedures

For Lesions Above the Diaphragm

• Mediastinoscopy and/or endobronchial ultrasound (EBUS) should be considered if enlarged and/or PET-avid mediastinal nodes are present, particularly for patients being considered for surgical intervention 1
• In the presence of contralateral pleural abnormalities detected on initial imaging, contralateral thoracoscopy may be performed to exclude contralateral disease 1
• Thoracoscopy can provide direct visualization and biopsy of pleural lesions when imaging findings are inconclusive 1

For Lesions Below the Diaphragm

• Laparoscopy is strongly recommended when there are suspicious findings for intra-abdominal disease on imaging and no other contraindications to surgery 1
• Laparoscopy can clarify whether transdiaphragmatic tumor invasion is present, which is often difficult to determine on imaging alone 1
• Laparoscopy can identify tumor directly extending through the diaphragm (T4) or peritoneal metastases 1

Special Considerations for Different Cancer Types

Lung Cancer

• For non-small cell lung cancer with suspected metastases, contrast-enhanced CT scan of the chest and upper abdomen should be performed initially 1
• PET-CT scan offers the highest sensitivity for mediastinal lymph nodes and distant metastasis assessment in lung cancer 1
• In the presence of a solitary metastatic site on imaging studies, cytological or histological confirmation should be obtained 1

Pleural Mesothelioma

• CT scan of the chest and upper abdomen with IV contrast is the standard initial imaging study 1
• FDG PET/CT scanning can identify metastatic disease not seen on CT and provides prognostic information based on the degree of FDG uptake 1
• Laparoscopy is particularly valuable when there is bulky tumor in the lower hemithorax involving the hemidiaphragm 1

Breast Cancer

• For early-stage breast cancer, routine imaging to detect distant metastases has low yield and is not recommended 1
• For advanced breast cancer, contrast-enhanced CT of chest and abdomen is appropriate 1
• Bone scan may be helpful to detect systemic bone metastasis when clinically indicated 1

Common Pitfalls and Caveats

• PET can be problematic to interpret in patients who have received a talc pleurodesis, leading to false-positive results 1
• Up to half of involved mediastinal lymph nodes may be located in areas not accessible with standard procedures like mediastinoscopy or EBUS 1
• False-positive imaging findings are common, necessitating pathologic confirmation of suspected metastatic disease 1
• Coronal and sagittal CT views are sometimes more helpful than axial cuts for evaluating diaphragmatic invasion, but interpretation can still be challenging 1
• While some institutions routinely perform invasive staging procedures, others use them selectively based on imaging findings and treatment plans 1

By following this systematic approach to the initial workup of lesions above and below the diaphragm in metastatic cancer, clinicians can accurately stage disease and develop appropriate treatment plans.