Optimal Tumor Reduction Rate and Modalities for Predicting pCR in Women With Breast Cancer.

BACKGROUND/AIM: To predict pCR during neoadjuvant chemotherapy is still difficult. The aim of this study was to evaluate the optimal tumor reduction rate and modalities for predicting pCR after two cycles of docetaxel. PATIENTS AND METHODS: We analyzed 52 patients with HER2-positive or triple-negative breast cancer. The tumor reduction rate was evaluated after two 3-week cycles of docetaxel (plus trastuzumab for HER2-positive cancer patients). Patients without progression completed two additional cycles of docetaxel and four cycles of an anthracycline-containing regimen. RESULTS: Twenty-eight patients achieved pCR. The optimal tumor reduction rates for predicting pCR were 23, 39, 32, and 40% for US, caliper, MMG, and MRI measurements, respectively. The AUC was highest for caliper measurements. The optimal modality for predicting pCR differed among subtypes. CONCLUSION: Although tumor reduction rate after two cycles of chemotherapy is highly predictive of pCR, the optimal cutoff value differed among the modalities and breast cancer subtype.