Abstract OT3-2-02: PreOperative window of endocrine therapy provides information to increase compliance: POWER PIINC: A feasibility study

Background: The addition of systemic therapy to the surgical treatment of breast cancer has improved survival of patients. A mainstay of systemic therapy in the setting of hormone receptor positive breast cancer is endocrine therapy. Despite the known advantages, the compliance with short and long term systemic endocrine therapy is less than ideal. Several studies report significant rates of non-compliance with endocrine therapy, either in patients never starting the medication or not completing the recommended multi-year course. It is estimated that as many as 10% of patients per year discontinue their therapy. We wondered why women would forgo such an important part of their treatment and how we might intervene to improve compliance. Using information gleaned from POWER PIINC, we hope to design a behavioral intervention study to see if the patient knowing her tumor9s preoperative response to endocrine therapy will improve long term compliance. In order to do such a study we would need to define the minimal length of preoperative endocrine therapy needed to detect measurable changes in the tumor. After 14 days of endocrine therapy, significant decreases in Ki67 can be seen in most hormone sensitive breast cancers. In fact two current studies are using this information (POETIC and ADAPT trials). Both of these trials are being conducted outside of the U.S. where operative therapy does not typically occur within a week or two of seeing the surgeon. POWER PIINC is a feasibility study to determine if we can detect changes in Ki67 with only 7 days of therapy. The results of POWER PIINC will inform the behavioral intervention trial. Trial Design: This is a prospective, single-arm feasibility study. Participants take tamoxifen for 7 days prior to surgery. Ki67 is measured pre (core biopsy) and post (surgical specimen) tamoxifen. Eligibility critieria: Non-pregnant women age 18 or older with a hormone positive (>1% ER or PR) clinical Stage 1 or 2 breast cancer who are candidates for surgical therapy of their breast cancer. No concurrent CYP2D6 inhibitors or other contraindications to tamoxifen. Specific Aims: Primary Objective: Demonstrate a significant reduction in Ki67 expression in tumors with 7 days of pre-surgical tamoxifen. Secondary Objectives: - Evaluate symptom patterns from baseline through 18 months of follow-up (presence, severity, and bother) -Evaluate 18-month endocrine therapy adherence -Evaluate change in attitude regarding endocrine therapy -Evaluate correlation between changes in Ki67 expression and symptom scores -Evaluate additional changes in proliferative markers (subset of PAM 50) Statistical Methods: A one-sample t-test will be applied to the log-ratio of Ki67 at resection to pre therapy. If this ratio is not normally distributed we will use a non-parametric Wilcoxon test. Secondary objectives will be analyzed using a variety of appropriate statistical tests. Accrual: Target accrual is 52 patients over 18 months. We opened this study in August of 2012. To date (9 months) we have accrued 23 patients. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT3-2-02.