Local Rib Invasion in Non-Small Cell Lung Cancer: A Bad Prognostic Factor that Owes a Characteristic Scintigraphic Appearance in Dual Phase Osseous Scintigraphy

As tumor grows within lung parenchyma or within bronchial wall, it ultimately invades lymphatic and vascular channels, resulting in spread to regional draining lymph nodes and remote metastatic sites, respectively. It appears that lymphatic spread occurs earlier than distant metastases, involving broncho-pulmonary (N1), mediastinal (N2-N3) and supra-clavicular lymph nodes (N3). The primary tumor can also spread locally, invading contiguous structures including mediastinal pleura, pericardium, other mediastinal structures, the chest wall or the diaphragm. This local spread might indicate a worse prognosis and alters the stage of disease (Sorenson et al, 1989 [16], Mountain, 1986 [12]).