Serial positron emission tomography (PET) for the prediction of breast cancer response to neoadjuvant chemotherapy: Does drug sequence matter?.

Abstract

The aims of this study were to (i) compare the effect of drug sequence on tumour glucose uptake volumes (SUV) using PET; and (ii) correlate SUV uptake changes with pathological response to chemotherapy in women with locally advanced breast cancer undergoing sequential chemotherapy with Taxotere and Anthracyclines. Women with biopsy confirmed breast cancer were randomised to receive either Taxotere (4 cycles) followed by Anthracyclines (4 cycles) or drugs in reverse order. All underwent FDG- PET before chemotherapy, after 4 cycles and after completion of chemotherapy. Changes in SUV after 4 cycles were compared to baseline and correlated to pathological response after surgery. At that stage, patients were classified into either complete elimination of tumour (cPR), small residual tumour (pPR) or no response (nPR).The two groups were compared using Mann Whitney U test, Kruskal Wallis and Chi Square test. Sixty patients were recruited, 31 receiving Taxotere followed by Anthracyclines and 29 receiving drugs in reverse order. Most patients presented with ductal carcinoma. Overall, 23% of tumours achieved cPR, 30% a pPR and 47% a nPR. There was no significant difference in the pathological response rates between the two drug regimens. Women receiving Anthracyclines followed by Taxotere who achieved cPR had a median SUV reduction of 83% after 4 cycles, while those who had nPR had a median SUV reduction of only 27% (P < 0.01). In contrast, SUV reductions in the other group of women were not statistically different between the 3 pathological response rates. FDG-PET appears to be a useful predictor of tumour response to Anthracycline-based chemotherapy in women with breast cancer.