Molecular Biologic Substaging of Stage I NSCLC Through Immunohistochemistry Performed on Formalin-Fixed, Paraffin-Embedded Tissue

Non-small cell lung cancer (NSCLC) is the most common cause of death by malignancy in both men and women in the United States (1 ). The current staging system for NSCLC considers the size and location of the primary tumor (T), the involvement of regional lymph nodes (N), and the presence of distant metastases (M) (2 ). The standard treatment of patients with stage I NSCLC (T1-2N0M0) is resection of the primary tumor with no adjuvant therapy. However, even after complete resection, the 5-yr survival rate is only 55–72%, mainly due to the development of distant metastases (2 –7 ). Therefore, a significant number of patients are under-staged and may benefit from adjuvant therapy.