The appropriate selection criteria for breast-conserving therapy (BCT) after neoadjuvant chemotherapy are poorly defined. The purpose of the current report was to develop a prognostic index to help refine selection criteria and to serve as a general framework for clinical decision-making for patients treated by this multimodality approach.
From a group of 340 patients treated with BCT after neoadjuvant chemotherapy, the authors previously determined 4 statistically significant predictors of ipsilateral breast tumor recurrence (IBTR) and locoregional recurrence (LRR): clinical N2 or N3 disease, residual pathologic tumor size > than 2 cm, a multifocal pattern of residual disease, and lymphovascular space invasion in the specimen. The M. D. Anderson Prognostic Index (MDAPI) was developed by assigning scores of 0 (favorable) or 1 (unfavorable) for each of these 4 variables and using the total to give an overall MDAPI score of 0–4.
The MDAPI stratified the 340 patients into 3 subsets with statistically different levels of risk for IBTR and LRR after neoadjuvant chemotherapy and BCT. Actuarial 5-year IBTR-free survival rates were 97%, 88%, and 82% for patients in the low (MDAPI overall score 0 or 1, n = 276), intermediate (MDAPI score 2, n = 43), and high (MDAPI score 3 or 4, n = 12) risk groups, respectively (P < 0.001). Corresponding actuarial 5-year LRR-free survival rates were 94%, 83%, and 58%, respectively (P < 0.001).
Patients with an MDAPI score of 0 or 1, which made up 81% of the study population, had very low rates of IBTR and LRR. The MDAPI enabled the identification of a small group (4%) of patients who are at high risk for IBTR and LRR and who may benefit from alternative locoregional treatment strategies. Cancer 2005. © 2005 American Cancer Society.