Tumor metabolism, blood flow changes, and prognosis by positron emission tomography: A prospective cohort of locally advanced breast cancer patients

Abstract

506 Background: Breast cancer patients with locally advanced tumors receive preoperative chemotherapy to provide early systemic treatment and assess in-vivo tumor response. Positron emission tomography (PET) has been used to follow tumor response to therapy, as pathologic response is predictive of patient outcome. We evaluated the prognostic utility of serial quantitative PET tumor blood flow (BF) and metabolism measurements. Methods: Fifty-five women with a primary diagnosis of locally advanced breast carcinoma (LABC) underwent dynamic [18F]-FDG and [15O]-water PET scans prior to and at midpoint of neoadjuvant chemotherapy. The FDG metabolic rate (MRFDG), transport (K1), and flux (Ki) parameters were calculated, and tumor blood flow was estimated from the [15O]-water study. Associations between tumor BF and MRFDG measurements and disease-free survival (DFS) and overall survival (OS) were evaluated using the Cox proportional hazards model. Results: Patients that had an increase in BF and K1, from baseline to mid-therapy measurements, had elevated recurrence and mortality risks compared to patients that had reductions in BF and MRFDG values. In multivariate analysis, changes in BF and K1 remained independent prognostic indicators of DFS and OS survival. Conclusions: PET measurements of tumor response prior to completion of neoadjuvant chemotherapy were predictive of patient outcome. Patients that failed to have a decline in BF and K1 experienced higher risks of recurrence and mortality that was largely independent of clinical tumor characteristics assessed in this study. These results suggest that tumor perfusion, measured directly by [15O]-water or indirectly by dynamic FDG PET, is highly predictive of outcome in neoadjuvantly treated breast cancer. No significant financial relationships to disclose.