Early assessment of tumor response using 18 F-FDG PET/CT after one cycle of systemic therapy in patients with recurrent and metastatic breast cancer.

OBJECTIVE: This study was conducted to evaluate the usefulness of early assessment of tumor response using fluorine-18-fludeoxyglucose positron emission tomography/computed tomography (18 F-FDG PET/CT) after one cycle of systemic therapy in patients with recurrent and metastatic breast cancer.

SUBJECT AND METHODS: Thirty-three patients with recurrent or metastatic breast cancer underwent 18 F-FDG PET/CT before and after one cycle of systemic therapy. Based on the European Organization for Research and Treatment of Cancer (EORTC) criteria, the maximum standardized uptake value (SUVmax) of the same lesions (up to a total of five) noted in the baseline and follow-up scans were summed (maximum of two per organ) as target lesions, and therapeutic response was evaluated. Log-rank and Cox methods were employed to determine progression-free survival (PFS) and overall survival (OS).

RESULTS: Complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), and progressive metabolic disease (PMD) was seen in 2, 16, 11, and 4 patients, respectively. The mean reduction rates of SUVmax between 84 target lesions in 18 responders (CMR/PMR) and 75 target lesions in 15 non-responders (SMD/PMD) were -55.8% (range, -100%- -1.2%) and 0.47% (range, -48.7%- +209.4%), respectively, with a significant difference (P<0.0001). Every lesion site (local lesion, lymph node metastasis, bone metastasis, lung metastasis, and liver metastasis) showed a similar tendency. Thirty patients showed progression, and 17 died due to breast cancer after a median of 38.5 months. Responders showed significantly longer PFS than non-responders (P=0.0038).

CONCLUSION: Fluorine-18-FDG PET/CT after one cycle of systemic therapy was able to reflect early metabolic changes regardless of the lesion site, and showed accuracy for early response evaluation and prediction of progression in patients with recurrent or metastatic breast cancer.