The usefulness of contrast enhanced F18-FDG PET/CT in evaluation of neoadjuvant chemotherapy response for breast cancer patients

Abstract

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Objectives: The purpose of this study is to evaluate clinical usefulness of contrast enhanced F18-FDG PET/CT in evaluation of neoadjuvant chemotherapy response for breast cancer patients.

Methods: 46 patients with newly diagnosed, locally advanced breast cancer who had contrast enhanced (CE) PET/CT scans within one month before and after 3 cycles of chemotherapy were evaluated. CE CT (i.v. bolus 60% w/v at 2-4mL/s) was performed immediately after PET scans for breast lesions. Peak SUV(pSUV) of the primary breast lesions and ipsilateral background breast parenchyma was taken. Response rate (RRpSUV) was compared with pathological response. Histiopathological response was divided into no response (NR), partial response (PR) and complete response (CR).

Results: 7 patients had CR after chemotherapy, with an average pSUV before chemotherapy was 10.2 in an average breast background uptake of 0.85. After chemotherapy, average pSUV reduced to 1.71 in an average breast background uptake of 0.86, resulting in an average RRpSUV of 79.1%±15. Of the 39 patients with PR, average pSUV of primary lesions was 8.3, in a breast background uptake of 1.0. After chemotherapy, primary lesion pSUV reduced to 2.97 in a background of 0.98, resulting in an average RRpSUV of 61.3%±22. All primary lesions after chemotherapy showed small residual mass and mild enhancement on contrast CT, except for two CR cases.

Conclusions: Reduction rates of the primary lesion on PET scans are helpful in predicting chemotherapy response. However, discrimination of lesion detection based on PET alone can be difficult, especially in cases with physiological increased breast parenchyma uptake and in CR cases. Because most post-chemotherapy lesions can be seen on contrast CT, they can be of help in locating lesions on PET scans.