Letrozole as primary medical therapy for locally advanced and large operable breast cancer.

Abstract

To investigate the efficacy of letrozole 2.5 mg and 10 mg used as primary neoadjuvant therapy for patients with locally advanced and large operable breast cancer. Twenty-four postmenopausal patients with locally advanced or large operable breast cancer were treated in two consecutive series with letrozole 2.5 mg (n = 12) or letrozole 10 mg (n = 12). Response at three months was measured by change in tumor volume according to WHO criteria (partial response was defined as a reduction in tumor volume > or = 65%). Tumor volumes were assessed clinically, by ultrasound and mammography, and pathologically. All 24 patients were estrogen receptor-positive, were considered 'receptor-rich', and mean age was 77.6 years and 71.6 years in the letrozole 2.5 mg and 10 mg treatment groups, respectively. There were five complete clinical responses and seven partial clinical responses in the patients treated with 2.5 mg letrozole, and nine partial responses and three patients with stable disease in patients treated with 10 mg letrozole. Assessed by ultrasound and mammography, the 12 patients treated with 2.5 mg had one complete response, nine partial responses and two with no change. In the 12 patients treated with 10 mg letrozole, imaging gave eight partial responses and four with no change. One patient treated with the 2.5 mg dose had a complete clinical and pathological response. There was no significant difference between the two doses in effect on tumor volume, and no recordable side effects associated with either dose. Letrozole used in a neoadjuvant setting is highly effective, producing clinically beneficial reductions in tumor volume allowing all patients to have breast conserving surgery, and has an acceptable safety profile.