Small Cell Lung Cancer

Preliminary Diagnosis: Small Cell Lung Cancer

I. What imaging technique is first-line for this diagnosis?

CT of the chest with IV contrast.

II. Describe the advantages and disadvantages of this technique for diagnosing small cell lung cancer.

Advantages

• Can adequately assess the T stage of the tumor.

• Useful for identifying pleural nodules, pleural plaques, pleural/ pericardial effusions, or metastasis.

• Higher sensitivity than PET/CT at visualizing brain metastases.

• CT of the chest should include upper abdomen to assess for adrenal metastasis.

• Easily accessible at most medical facilities.

• Better tolerated in obese or claustrophobic patients.

Disadvantages

• Low sensitivity (40-84%) and specificity (57-94%) for identifying mediastinal and lymph node involvement.

• Limited in detecting chest wall or parietal pleural invasion.

• Requires the use of IV contrast.

• Exposure to ionizing radiation.

III. What are the contraindications for the first-line imaging technique?

• Contraindicated in pregnant patients, especially during the first and second trimesters.

• Relative contraindication in patients with iodine allergies.

• Relative contraindication in patients with renal failure.

IV. What alternative imaging techniques are available?

• PET/CT (commonly used as adjunct to chest CT for full staging)

• MRI of chest

• Chest X-ray

V. Describe the advantages and disadvantages of the alternative techniques for diagnosing small cell lung cancer.

PET/CT

Advantages

• Delineates anatomy and also determines metabolic activity of lesions.

• Improved sensitivity (98%) versus CT alone at identifying mediastinal invasion and lymph node metastases.

• Improved sensitivity and specificity versus CT alone for detecting extrathoracic metastatic disease.

• Can drastically alter management by correctly staging patients as limited or extensive stage, which ultimately dictates treatment course.

• Helps with radiation treatment planning and assessing disease response after definitive therapy.

Disadvantages

• Expensive and not easily accessible at certain medical centers.

• Good positive predictive value, but poor negative predictive value.

• High false positive rate, which may require further pathologic confirmation.

• Sensitivity not as high in visualizing brain metastases.

MRI of chest/abdomen/brain with IV contrast

Advantages

• Can help better assess extrathoracic and chest wall invasion.

• Does not expose patient to ionizing radiation.

• Can help delineate brain, adrenal, or spinal metastases.

• Higher sensitivity than PET/CT at visualizing brain metastases

• MRI of the brain with contrast should be obtained in all patients with suspected or confirmed diagnosis of small cell lung cancer prior to starting therapy

Disadvantages

• Expensive.

• Time consuming.

• Requires significant patient cooperation to minimize motion artifact.

• Loss of signal from physiologic lung movement.

• Not as well tolerated in patients that are obese, claustrophobic, or unable to hold their breath.

Chest X-ray

Advantages

• Cheap, easily accessible, and easy to administer.

• Requires lower doses of radiation exposure.

• Is helpful to compare with previous films to determine if further workup is necessary.

Disadvantages

• Unable to determine full staging of disease.

• Insufficient to assess mediastinal and lymph node metastases.

• Cannot determine extrathoracic metastases.

VI. What are the contraindications for the alternative imaging techniques?

PET/CT

• Contraindicated in pregnant women.

MRI chest/abdomen/brain with IV contrast

• Contraindicated in patients with pacemakers and other implantable, MRI-incompatible devices.

• Gadolinium contrast is contraindicated in patients with a GFR ≤ 30

CXR

• There are no major contraindications for this imaging modality. Some institutions may require consent for pregnant patients.