Purpose: The aim of the study was to evaluate the clinical value of scintimammography (SMG) with technetium-99m methoxyisobutylisonitrile (Tc-MIBI) for evaluating the efficacy of neoadjuvant chemotherapy (NAC).
Materials and methods: A total of 65 patients with advanced breast cancer (BC) were included in the study. Planar SMG with 740 MBq of Tc-MIBI was performed before the start and after two to three and four to six cycles of NAC. NAC efficacy was estimated as progression (grade I), stabilization (grade II), partial effect (grade III), prominent efficacy (grade IV), and complete response (grade V). In 59 women, histopathologic verification of BC response to NAC was performed according to the Miller-Payne classification with the same scores as were used in the evaluation of scintigraphic response.
Results: After two to three cycles of NAC, disease progression was detected in five of 65 (7.7%) patients. In 27 (41.5%) patients SMG detected early stabilization of BC. Only one of these patients achieved prominent (grade IV) response after the end of NAC. Partial (grade III) response after two to three cycles of NAC was seen in 24 (36.9%) patients. One-third of them had grades IV-V response at the end of treatment. The most promising was the group of nine (13.8%) patients with early-grades IV-V response, all of which transformed to complete response at the end of NAC. As per histopathologic verification, early SMG had 85.7% sensitivity, 94.2% specificity, and 93.2% accuracy in predicting complete pathologic response to four to six cycles of NAC.
Conclusion: After two to three cycles of NAC, SMG with Tc-MIBI can determine patients with low, intermediate, and high probability of complete response to five to six cycles of NAC Video Abstract: http://links.lww.com/NMC/A43.