18F-FDG PET/CT Findings and Circulating Tumor Cell Counts in the Monitoring of Systemic Therapies for Bone Metastases from Breast Cancer.

Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2010 Jul 21; In press

De Giorgi U, Mego M, Rohren E EM, Liu P, Handy B BC, Reuben J JM, Macapinlac H HA, Hortobagyi G GN, Cristofanilli M, Ueno N NT

Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.

Our objective was to compare the predictive significance of (18)F-FDG PET/CT findings and circulating tumor cell (CTC) count in patients with bone metastases from breast cancer treated with standard systemic therapy. METHODS: Breast cancer patients with progressive bone-only metastatic disease without visceral metastases starting a new line of systemic therapy underwent (18)F-FDG PET/CT and had CTC counts determined before and during treatment. Disease status was reassessed by CTC count (>/=5 vs. <5 CTC/7.5 mL of blood) and (18)F-FDG PET/CT approximately 2-4 mo after initiation of the new systemic therapy. RESULTS: CTC counts at follow-up agreed with the (18)F-FDG PET/CT assessment in 43 (78%) of the 55 evaluable patients. Of the 12 patients with discordant CTC and (18)F-FDG PET/CT results, 8 (66%) had >/=5 CTCs, with no evidence of progressive disease at the time of the (18)F-FDG PET/CT study, whereas 4 (33%) had <5 CTCs, with evidence of progressive disease by (18)F-FDG PET/CT. (18)F-FDG PET/CT findings and follow-up CTC counts were found to be significantly associated with both progression-free survival (P = 0.02 and P < 0.0001, respectively) and overall survival (P = 0.02 and P = 0.01, respectively). In multivariate analysis, the (18)F-FDG PET/CT assessment remained as the only predictive factor for progression-free survival (P < 0.0001), whereas estrogen receptor status was the only predictive factor for overall survival (P = 0.01). CONCLUSION: (18)F-FDG PET/CT is a useful tool for therapeutic monitoring in patients with bone metastases from breast cancer. Prospective studies are needed to define the role of (18)F-FDG PET/CT and CTC in the setting of response discordance to establish bone-dominant disease as a tumor-response measurable disease.

Keywords: 18F-FDG PET Circulating Tumor Cell Breast Cancer