How is the extent and local invasion of the primary tumor determined on lung cancer imaging?

Updated: Jan 28, 2019
  • Author: Omar Lababede, MD; Chief Editor: Eugene C Lin, MD  more...
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In clinical practice, the endobronchial extent of the primary neoplasm is primarily and accurately defined by bronchoscopy. Imaging, especially CT scanning and MRI, can suggest the extent of the tumor by delineating its endobronchial component or by demonstrating associated secondary changes such as postobstructive pneumonitis or atelectasis.

Visceral pleural invasion (VPI) is an important finding that advances the classification from T1 to T2. In the seventh edition of the TNM staging, the IASLC implemented a standardized definition of the visceral pleural invasion as extension beyond the elastic layer up to the visceral pleural surface (based on pathologic examination with elastic stains). [19] Invasion of the pleura into an adjacent ipsilateral lobe should be classified as T2. Imaging is limited in reliably confirming invasion in the presence of contact between the mass and the visceral pleura.

Measurement of the ratio of the interface between the tumor and adjacent structure (arch distance) to the maximum tumor diameter has been suggested as a high performance criterion of pleural invasion. [20] A ratio greater than 0.9 achieved sensitivity and specificity of 89.7% and 96%, respectively.

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