Neoadjuvant endocrine therapy for resectable breast cancer: A systematic review and meta-analysis

The role of neoadjuvant endocrine therapy for resectable breast cancer is not well established, despite encouraging results obtained in the metastatic and adjuvant settings. This systematic review aims to examine existing medical literature on neoadjuvant hormone therapy (HT).

Data from prospective, randomized trials was included if comparing neoadjuvant HT versus surgery alone without adjuvant treatment, or neoadjuvant HT versus chemotherapy (CT), or HT plus CT versus CT alone, or HT plus CT versus HT alone, or two distinct HT. Odds Ratios (OR) were calculated from pooled data.

Five studies compared HT with tamoxifen versus HT with aromatase inhibitors (AI). A meta-analysis of their results demonstrated superiority of AIs in overall response rate (ORR) (OR 1.9; 95% CI 1.17-3.08). Two trials compared HT against CT, and pooled data from them demonstrated a trend favoring CT (OR for ORR 0.75; 95% CI 0.35-1.6). That trend disappeared when only postmenopausal women were considered (OR 1.01; 95% CI 0.62-1.63). One trial compared HT plus CT with no neoadjuvant treatment, and obtained an 83% ORR. One trial compared HT plus CT versus CT alone and found a non-significant increase in ORR for adding HT to CT (OR 1.48; 95% CI 0.58-3.77). No trial compared HT plus CT versus HT alone.

Neoadjuvant HT is a safe and feasible option, but it cannot be considered equivalent to CT. If neoadjuvant HT is performed, AIs are preferable over tamoxifen due to higher response rates.