Primary systemic therapy in operable breast cancer.

PURPOSE: Laboratory studies suggest that primary systemic therapy (PST) could improve control of micrometastatic disease and impact on overall survival (OS). This article examines the rationale for and preclinical and clinical data of PST in operable breast cancer and the potential role of intermediate biomarkers as predictive and/or prognostic factors for response and survival. DESIGN AND
METHOD: We conducted an extensive literative review (including MEDLINE) on preclinical studies, single-arm feasibility studies, large randomized single- and multi-institutional trials, and laboratory correlate studies of PST in breast cancer.
RESULTS: Small trials in locally advanced disease showed high initial rates of response and local control. Six randomized clinical trials (RCTs) of PST for palpable, operable breast cancer have been reported since 1991 (from 204 to 1,523 patients each). These data clearly show a small but significant (less than 10%) absolute increase in the use of breast-conservation treatment (BCT) with similar rates of local control. Although one study showed better disease-free survival (DFS) and another showed better OS, most studies did not show any survival advantage of primary versus adjuvant systemic therapy. Thus far, pathologic complete response seems to be the best predictor of survival, but clinical response assessment correlates poorly with pathologic response. Pilot studies demonstrated feasibility of procuring tissue at diagnosis and after treatment for assays of potential intermediate biomarkers. Initial data suggest a potential correlation between markers of proliferation and apoptosis and in vivo chemotherapy sensitivity.
CONCLUSION: Thus far, RCTs of PST versus standard adjuvant therapy have not shown any clear benefit for DFS or OS in early breast cancer. Ongoing trials should determine if specific subsets of patients at risk would benefit from additional systemic therapy and the potential role of intermediate biomarkers in identifying such women. Although PST results in a small increase in the rate of BCT with similar rates of local control, current PST strategies should not replace standard adjuvant approaches. Rather, they represent an acceptable alternative to women with palpable, operable tumors and an excellent arena for clinical trials.