Interim 18F-FDG-PET/CT predicts early response to neoadjuvant chemotherapy in breast cancer

초록

Objectives To retrospectively evaluate interim 18F-FDG-PET/CT in predicting early response to neoadjuvant chemotherapy in breast cancer. Methods Twenty seven patients with large or locally advanced breast cancer were included. One patient was invasive lobular carcinoma and the others were invasive ductal carcinoma on initial breast biopsy. They all underwent 6 or 8 cycles of neoadjuvant chemotherapy. They took PET/CT scan at baseline, and after the 3rd or 4th cycle (interim). Breast surgery was performed after completion of neoadjuvant chemotherapy. Maximum standardized uptake value (SUVmax) in each PET/CT scan was measured in each patient. The metabolic response was calculated as follows: ΔSUV(%) = 1st SUVmax - 2nd SUVmax / 1st SUVmax × 100 (%). We compared pCR and non-pCR group. Pathologic complete response (pCR) was defined as no invasive and no in situ residuals in breast and nodes. Then among the non-pCR patients, we compared the patient according to pathologic grade using Nottingham histologic grade. Results Five patients confirmed as having pCR and 22 patients showed residual pathology non-pCR). Mean SUVmax of pCR and non-pCR groups in the baseline PET/CT scan were 8.90 ± 5.12, and 8.59 ± 3.54, respectively (p=0.74). Mean SUVmax of pCR and non-pCR groups in the interim PET/CT scan were 1.62 ± 0.31, and 2.98 ± 2.00, respectively (p=0.03). Mean SUVmax change between baseline and interim PET/CT scan of pCR and non-pCR groups were 75.82 ± 15.88% and 64.88 ± 14.29%, respectively (p=0.04). A cut off ΔSUV value of 78.26% is proposed with a sensitivity of 80% and a specificity of 90.91%. Among the non-pCR group, SUVmax change in patients with medium prognosis (grade 2) was higher than in patients with bad prognosis (grade 3) (p=0.04). A cut off ΔSUV value of 69.89% distinguishes both groups, with a sensitivity of 66.67% and a specificity of 77.78%. Conclusions It is possible to use interim FDG PET-CT as effective method to predict early response in neoadjuvant chemotherapy treated breast cancer patient.