- Stage 1 (phase II feasibility study) After undergoing planned curative resection followed by ex vivo sentinel lymph node mapping (SLNM). Resected samples are examined. The sentinel lymph nodes of those deemed pN0 disease (no macroscopic metastases or angioinvasion) are further evaluated for micrometastases by serial sectioning and immunohistochemistry using pan-cytokeratin. pN0micro+ disease are defined as isolated tumor cells (ITC) < 0.2 mm or micrometastasis 0.2 - 2 mm. Patients with pN0 disease are followed-up once every 6 months for 3 years and then annually for 2 years.