Background: A pathologic complete response (pCR) and minimal residual disease (pMRD) after preoperative chemotherapy (PCT) for early stage or locally advanced breast cancer (BC) correlates with a good prognosis.
Methods: Patients who received from 6 to 8 cycles of PCT for BC were monitored by (18)F-2-fluoro-2-deoxy-D-glucose positron emission tomography ((18)F-FDG-PET), and the maximal standardized uptake value (SUVmax) was calculated at baseline, after 2 cycles, after 4 cycles, and at the end of PCT. SUVmax percentage changes (Delta-SUV) were compared with the pathologic response rate. Patients who had a pCR or pMRD in the tumor and an absence of cancer cells in ipsilateral axillary lymph nodes were defined as having obtained an optimal pathologic response (pR), whereas all the other conditions were classified as a pathologic nonresponse (pNR).
Results: Of 34 patients, 7 (21%) achieved a pR (3 patients had a pCR, and 4 patients had pMRD). After the second cycle, the Delta-SUV threshold with optimal negative predictive value to predict a pR was 50%. Twenty-six patients (76%) had a Delta-SUV >50%, including all 7 patients who had a pR and 19 patients who had a pNR. Conversely, all 8 patients who had a Delta-SUV < or =50% had a pNR. All 8 of those patients had estrogen recepetor-positive tumors.
Conclusions: Early evaluation of metabolic response by (18)F-FDG-PET during PCT was able to identify 30% of patients, all with estrogen receptor-positive tumors, who would not obtain pR after completion of chemotherapy program.