Predictive value of FDG PET/CT for pathologic axillary node involvement after neoadjuvant chemotherapy.

Background: The purpose of this study was to determine the usefulness of sequential FDG PET/CTs for prediction of axillary lymph node (ALN) status after neoadjuvant chemotherapy (NAC).

Methods: Seventy-seven stage II or III breast cancer patients who received 3 cycles of neoadjuvant docetaxel/doxorubicin chemotherapy were enrolled in this prospective study. FDG PET/CTs were acquired before chemotherapy and after the first cycle of chemotherapy for early metabolic response prediction.

Results: Patients with pN0 had significantly lower post-NAC ALN standard uptake value (SUV) than those who were pN+ (1.22 ± 1.46 in pN0 vs. 2.13 ± 1.99 in pN+, P = 0.017). Post-NAC ALN size on CT also differed according to pathologic ALN status (6.3 mm in pN0 vs. 11.1 mm in pN+, P = 0.014). When serial FDG PET/CT and chest CT were used, patients with an SUV > 1.5 and post-NAC ALN size ≥10 mm on CT did not achieve pN0 (specificity 100% and positive predictive value 100%).

Conclusions: The serial FDG PET/CT after NAC could predict the pathologic status of ALN before surgery in stage II/III breast cancer. Our findings suggest that the combined use of serial FDG PET/CTs and chest CT might provide better information regarding ALN before surgery.