Breast cancer is increasingly treated with neoadjuvant chemotherapy to improve surgical resectability and evaluate tumor response, which is assessed histopathologically. Several histopathologic classification systems have been previously described for assessment of treatment response.
To test performance in a side-by-side comparison of several histopathologic classification systems after neoadjuvant chemotherapy with clinical outcome.
Sixty-two patients were enrolled in a randomized trial receiving sequential neoadjuvant chemotherapy with doxorubicin and paclitaxel. Histologic sections from the patients' tumors sampled before (core biopsy) and after treatment (excision or mastectomy) were reviewed. Histologic response was assessed following National Surgical Adjuvant Breast and Bowel Project protocol B18, Miller-Payne grading, Sataloff tumor and nodes, Residual Cancer Burden (RCB), and Residual Disease in Breast and Nodes (RDBN). Pathologic classification results were correlated with survival using Kaplan-Meier and Cox hazards regression with a median follow-up of 93 months.
RDBN was associated with distant disease-free survival by univariate and multivariate analysis (P = .01 and .004, respectively), as were lymph node metastases (P = .02 and .01, respectively). Five patients (8%) had complete pathologic response after neoadjuvant chemotherapy, and none of them relapsed during the study period. Survival was shorter among patients with higher Residual Cancer Burden scores, but the associations were not significant. Miller-Payne grading and Sataloff tumor scores were not correlated with survival.
Evaluation of breast specimens after neoadjuvant chemotherapy by the composite index RDBN correlates with long-term outcome. The residual disease in breast and nodes system is suitable for routinely processed pathology cases. This study confirms the importance of lymph node status after neoadjuvant chemotherapy and favorable outcome in patients with pathologic complete response.