A new study has reported that factors predictive of disease progression during chemotherapy include race, advanced tumor stage, high nuclear grade, high proliferation score, and negative hormone receptor status (ER-/PR-). Although the tumors of most breast cancer patients who receive neoadjuvant chemotherapy respond to the treatment, the tumors continue to grow during chemotherapy in a small fraction of patients. Predictors of response to chemotherapy have been reported, but predictors of disease progression have not previously been identified. If predictors of cancer progression during chemotherapy could be determined, patients who might benefit from a first-line surgical approach or from novel targeted therapies could be identified.

To perform the study, medical records of 1,928 patients with stage I to III breast cancer who received anthracycline and/or taxane based chemotherapy were reviewed. Patients with any pathological response or stable disease were compared to patients who experienced breast cancer progression during chemotherapy.

A total of 1,762 of the study population (91%) were found to have favorable response to chemotherapy (of any degree), 107 (6%) had stable disease, and 59 (3%) experienced disease progression at some point during chemotherapy. Factors predictive of disease progression included African American race, tumor (T) status, and breast cancer stage. Histopathologic features of cancer that progressed were high tumor grade, high Ki-67 proliferation score, and ER-/PR- status. In multivariate analysis, pre-chemotherapy T status, race, and ER status were found to be independent predictors of progression. Not surprisingly, disease progression also was a negative predictor of distant disease-free survival and overall survival, highlighting the aggressive nature of breast cancer that is able to grow despite being subjected to chemotherapy. The authors conclude that factors predictive of disease progression during chemotherapy include race, advanced tumor stage, high nuclear grade, high Ki-67 score, and ER-/PR- status. However, these variables are also associated with response to chemotherapy, so that the study failed to meet the goal of uncovering a unique profile or set of factors that could identify patients at risk for progression on standard chemotherapy.