1472 - Dedicated breast PET for predicting residual disease after breast cancer neoadjuvant chemotherapy

Background

Diagnostic methods to evaluate the response to breast cancer neoadjuvant chemotherapy (NAC) have been established. Dedicated breast PET (DbPET) is a high-resolution molecular breast imaging method, and we investigated the ability of DbPET to predict the presence of residual primary tumors after NAC, compared with whole-body PET (WBPET).

Methods

Forty-five patients (47 tumors) underwent WBPET and ring-type DbPET after NAC, and tumors were completely resected between January 2016 and March 2017. The pathological response was classified as complete remission (ypT0), residual intraductal disease (ypTis), or residual invasive disease (ypT≥1). Standardized uptake value (SUV) and tumor-to-normal tissue ratio (TNR) were assessed.

Results

Twelve patients achieved ypT0 and 5 developed ypTis. DbPET detected all cases of ypTis, and WBPET detected only one case of ypTis. The sensitivity, specificity, and accuracy of WBPET for ypT≥is were 54.3%, 83.3%, and 61.7%, respectively, and those of DbPET were 77.1%, 83.3%, and 78.7%, respectively. In the ypT0/ypTis/ypT≥1 groups, the median WBPET-SUV, DbPET-SUV, and DbPET-TNR were 1.0/0.9/1.1, 1.7/1.8/2.2, and 1.0/1.6/1.7 (P = .134, .077, and .008), respectively (Table). Area under the curves of WBPET-SUV, DbPET-SUV, and DbPET-TNR for predicting ypT≥is were 0.610, 0.648, and 0.807, respectively.Table:

210P Comparison of predicting indexes for predicting pathological response

Conclusions

DbPET was superior to detect residual primary tumors, especially noninvasive carcinoma, after NAC than WBPET. TNR was expected as the better parameter of pathological evaluation than SUV.

Clinical trial identification

Legal entity responsible for the study

N/A

Funding

None

Disclosure

All authors have declared no conflicts of interest.