Comparison of stage-specific outcome of breast cancer based on 5th and 6th AJCC staging system

Background and Objectives: To investigate the appropriateness of the new staging system (AJCC 6th edition) for breast carcinoma. Methods: We reviewed the clinicopathologic data of 1,768 breast cancer patients, and their disease stages were re-categorized by the new system. The overall survival (OS) and distant relapse free survival (DRFS) rates were compared between those patients whose stages by the old system (AJCC 5th edition) remained the same (the remainders) and those patients whose stages moved up (the upstaged cases) as well as between the subgroups in the new system. Results: The 10-year DRFS rates of the upstaged cases in each stage were poorer than those of the remainders, and statistical significance was demonstrated for stage UB and stage IIIA. The 10-year OS rates were also poorer in the upstaged cases, and statistical significance was demonstrated for stage IIIA. Subgroup analysis within the new system between the node-negative versus node-positive subgroups in stages IIA and IIB showed a significant OS difference. The DRFS difference was also shown between the subgroups in stage IIA. Conclusions: The new staging system seems to more accurately reflect disease outcome, however, a re-evaluation might be required to reflect the impact of nodal involvement upon the new staging system.