Purpose: To evaluate, in breast cancer patients treated by neoadjuvant chemotherapy, the predictive value of reduction in FDG uptake with regard to complete pathological response (pCR).
Methods: Forty-seven women with non-metastatic, non-inflammatory, large or locally advanced breast cancer were included. Tumour uptake of FDG was evaluated before and after the first course of neoadjuvant chemotherapy. Four indices were used: maximal and average SUV without or with correction by body surface area and glycaemia (SUV(max), SUV(avg), SUV(max-BSA-G) and SUV(avg-BSA-G), respectively). The predictive value of reduction in FDG uptake with respect to pCR was studied by logistic regression analysis. Relationships between baseline [(18)F]FDG uptake and prognostic parameters were assessed.
Results: The relative decrease in FDG uptake (DeltaSUV) after the first course of neoadjuvant chemotherapy was significantly greater in the pCR group than in the non-pCR group (p < 0.000066). The four FDG uptake indices were all strongly correlated with each other. A decrease in SUV(max-BSA-G) of 85.4% +/- 21.9% was found in pCR patients, versus 22.6% +/- 36.6% in non-pCR patients. DeltaSUV(max-BSA-G) <-60% predicted the pCR with an accuracy of 87% and DeltaSUVs were found to be only factors predictive of the pCR at multivariate analysis. An elevated baseline SUV was associated with high mitotic activity (p < 0.0016), tumour grading (p < 0.004), high nuclear pleomorphism score (p < 0.03) and negative hormonal receptor status (p < 0.005).
Conclusion: In breast cancer patients, after only one course of neoadjuvant chemotherapy the reduction in FDG uptake is an early and powerful predictor of pCR.