18F-FDG PET/CT findings and circulating tumor cell counts in the monitoring of systemic therapies for bone metastases from breast cancer.
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 (> or = 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 > or = 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).


CONCLUSIONS
(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.
De Giorgi
Ugo
U
Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
Mego
Michal
M
Rohren
Eric M
EM
Liu
Ping
P
Handy
Beverly C
BC
Reuben
James M
JM
Macapinlac
Homer A
HA
Hortobagyi
Gabriel N
GN
Cristofanilli
Massimo
M
Ueno
Naoto T
NT
D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary* / Q000628:therapy; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D002452:Cell Count; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D053208:Kaplan-Meier Estimate; D009360:Neoplastic Cells, Circulating; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics; D013534:Survival; D014055:Tomography, Emission-Computed
D019788:Fluorodeoxyglucose F18; D019275:Radiopharmaceuticals; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human