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Evaluation of early response to primary systemic chemotherapy in breast cancer patients by 18FDG PET: Preliminary findings from the Arianna Project 01.

10722 Background: Pathological complete remission after primary systemic chemotherapy (PSC) for early breast cancer (BC) correlates with a better prognosis in terms of survival. The Arianna Project 01 was designed to study the relationship between clinical, hystological, biological, gene-expression profile characteristics and response to PSC in BC pts.


METHODS
Pts treated with 6 cycles of adriamycin 60 mg/m2 and paclitaxel 200 mg/m2 were evaluated at baseline and before each cycle by physical exam, 18FDG-PET, circulating tumor cells and bio-markers (serum EGFR, VEGF, UPA, plasma PAI-I and the circulating portion of HER2/neu receptor). At baseline and every other cycle mammography, ultrasound and breast MRI were also done. This preliminary report is focused on the correlation between PET monitoring and pathological response. Changes in tumoral 18FDG uptake, expressed as Standardized Uptake Value (SUV), were compared with the hystopathological response assessed according to Miller-Payne scale, which estimates the Tumour Regression Grade (TRG).


RESULTS
Up to now 12 pts (T > 2 cm) have been enrolled in the study and 9 completed PSC and were submitted to surgery. Baseline PET was abnormal in all pts (SUVmax range: 3.9-17.1). No cases of complete pathological remission have been observed so far. In 2 pts the TRG was grade 4 ( > 90% reduction of tumor cells), TRG was grade 3 (30 to 90% reduction) in 3 cases, grade 2 (minor loss of tumor cells) in 4 cases. After the 1st, the 2nd and the 3rd cycle of PSC the SUV decrease (Δ SUV) in primary tumors was ≥ 50%, ≥ 75% and ≥ 85% only in the two pts that at the end of PSC obtained a TRG grade 4 (see table ).


CONCLUSIONS
Our preliminary results suggest that an early prediction of pathological response by PET is possible and the optimal timing to perform PET during PSC could be after 2 or 3 cycles. The study is still ongoing and the relationship between evaluation performed by PET and by mammography, ultrasound and breast MRI will be presented at the ASCO meeting. [Table: see text] No significant financial relationships to disclose.