Neoadjuvant tamoxifen for operable breast cancer: a need for phase III studies?

We conducted a case-control study to analyze the effect of neoadjuvant tamoxifen on steroid receptors and histologic grade and to evaluate the feasibility of phase III studies in operable breast cancer. Between 1987 and 1990, 107 patients without clinical metastases who had had no chemotherapy preoperatively, were treated preoperatively with 20 mg/day of tamoxifen for 3 weeks. Of them, 92 were matched with controls for age at diagnosis, year of diagnosis, presence or absence of lymph node involvement, and preoperative radiotherapy. The percentage of ER1 tumors (P = .03) and the mean and median ER levels (P<.001 for both) were lower in the tamoxifen group than in the control group. In six patients analyzed longitudinally, the mean ER decreased from 52 to 19 fmol/mg protein. The difference in relapse-free survival between the two groups was not significant (mean follow-up 87 months). This study suggests a decrease in ER content in patients treated with neoadjuvant tamoxifen. This change may thus be taken into account when ER determination is performed after tamoxifen therapy is started. Further randomized trials should determine whether patients with operable breast cancer benefit from neoadjuvant tamoxifen treatment.