American Joint Committee on Cancer Tumor–Node–Metastasis Stage After Neoadjuvant Chemotherapy and Breast Cancer Outcome

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Abstract
Background: Response to neoadjuvant chemotherapy is used as an intermediate endpoint for breast cancer relapse and survival. Most breast cancer response classification systems use pathologic complete response, either alone or in conjunction with clinical assessments, to categorize response. We examined the ability of the revised 2003 American Joint Committee on Cancer (AJCC) tumor–node–metastasis (TNM) staging system, which considers both the number of involved axillary lymph nodes and the extent of tumor in the breast to predict patient survival after neoadjuvant chemotherapy for breast cancer. Methods: We assessed the pathologic stage of residual tumor in 132 patients with nonmetastatic breast cancer after they had undergone neoadjuvant chemotherapy and examined the association between AJCC TNM stage and subsequent distant disease–free survival and overall survival. All statistical tests were two-sided. Results: At a median follow-up of 5 years, pathologic stage in the surgical specimens after neoadjuvant chemotherapy using the revised AJCC system was strongly associated with both distant disease–free survival and overall survival. A higher pathologic stage of residual tumor after neoadjuvant chemotherapy was associated with a statistically significant lower rate of distant disease–free survival (stage 0: 95%, stage I: 84%, stage II: 72%, and stage III: 47%; Ptrend <.001). The 5-year distant disease–free survival for patients with residual stage IIIC tumors was only 18% (95% CI = 0% to 36%). Conclusion: Classification of residual tumor in the breast and axillary surgical specimens after neoadjuvant chemotherapy using the revised AJCC TNM system is useful for predicting distant relapse and survival.