Abstract
8164 Background: Endocrine therapy is effective in downstaging patients (pts) with primary BC and may be considered in elderly women. TOR is a triphenylethylene selective ER modulator differing from tamoxifen for the presence of a chlorine atom. Methods: A two-stage, phase II study was conducted to investigate efficacy of TOR (60 mg/day) as a short-term pre-operative therapy (3 months) in elderly pts with newly diagnosed, ERα+ operable or locally advanced (T2-T4b, N0–1) BC. The relationship of intratumor levels of mRNA ERα and β with objective responses was investigated, and serum markers of bone metabolism were also evaluated. Diagnosis was established by mammography and core-biopsy. A cut-off of 10% of stained cells was used to define ERα positivity. ER isoforms was assessed by RT-PCR. At baseline and monthly thereafter, tumor size was estimated clinically (by calipers). After 3 months of TOR, all pts were referred to the breast surgeon. Results: Forty-seven evaluable pts entered the study. Median age was 78 years (range, 65–90); median value of tumor diameter was 3.0 cm (range, 2.1–6.0). Most pts (72%) were classified as T2 without nodal involvement. By WHO criteria, we observed 20 regressions (4 CRs+16 PRs; response rate 42.6%; 95% CI, 28–58%), 25 stabilizations and 2 progressions. Among the 25 pts with stabilizations, 14 achieved initial reduction in tumor size (decrease ≥25% in the product of the largest diameters). In 38 assessable pts, ERα but not ER β mRNA levels were higher in responsive compared with unresponsive pts (median densitometric values: 549 vs 320 for ERα; 91 vs 84 for ERβ). Conclusions: This study indicates that, over a period of 3 months, pre-operative TOR induces a worthwhile response rate in elderly women with primary ER+ BC. ERβ mRNA was not predictive of response to TOR. Bone metabolism evaluation is in progress. No significant financial relationships to disclose.
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