Purpose: This study examines the use of [(18)F]fluorodeoxyglucose positron emission tomography (FDG-PET) for the evaluation of the therapeutic response for patients treated with high-dose chemotherapy (HDC) with autologous stem cell transplantation for metastatic breast cancer (MBC) focusing on prognostic stratification.
Patients and methods: Forty-seven patients with MBC were treated with a maximum of three cycles of HDC. Therapeutic response was assessed with conventional imaging (CImg; including a computed tomography in all cases and ultrasound, mammography, and bone scanning as clinically indicated) and by FDG-PET study performed after the last cycle of HDC. Parameters analyzed for predicting survival were FDG-PET and CImg results, pattern of disease, prior treatment, and HDC regimen.
Results: Complete responses were observed in 16 patients (37%) with CImg and 34 patients (72%) with FDG-PET. The FDG-PET result was the most powerful and independent predictor of survival; patients with a negative post-treatment FDG-PET had a longer median survival than patients with a positive FDG-PET (24 months v 10 months; P < .001). By multivariate analysis the relative risk (RR) of death was higher in patients with FDG-PET-positive disease (RR, 5.3), prior anthracycline treatment (RR, 3.3), or with visceral metastasis (RR, 2.4).
Conclusion: A single FDG-PET study performed after completion of HDC for MBC can powerfully stratify for survival. This may have implications for how we should assess outcome after conventional-dose therapy for MBC and warrants additional study.