Objective: To evaluate the accuracy of magnetic resonance imaging (MRI) of the breasts in the identification of a pathological complete response in patients with breast cancer undergoing neoadjuvant chemotherapy (NAC).
Materials and methods: This was a single-center, retrospective, observational study designed to validate a diagnostic test. The following variables were evaluated: age; results of the histological and immunohistochemical analysis of the biopsy; post-NAC MRI findings; and results of the histological analysis of the surgical specimen, using the residual cancer burden index. The radiological response, as assessed by MRI, was compared with the pathological response, as assessed by histological analysis of the surgical specimen (the gold standard method).
Results: We evaluated 310 tumors in 308 patients. The mean age of the patients was 47 years (range, 27-85 years). For identifying a pathological complete response, breast MRI had an overall accuracy of 79%, with a sensitivity of 75%, specificity of 83%, positive predictive value of 75%, and negative predictive value of 83%. When that accuracy was stratified by molecular subtype, it was best for the HER2 subtype, with a sensitivity and specificity of 82% and 89%, respectively, followed by the triple-negative subtype, with a sensitivity and specificity of 78% and 83%, respectively.
Conclusion: Breast MRI showed good accuracy in the prediction of a pathological complete response after NAC. The sensitivity and positive predictive value were highest for the HER2 and triple-negative subtypes.
Objetivo: Avaliar a acurácia da ressonância magnética (RM) das mamas na identificação de resposta patológica completa em pacientes com câncer de mama submetidas a quimioterapia neoadjuvante (QTN).
Materiais e métodos: Teste de validação diagnóstica, realizado por meio de estudo observacional, unicêntrico e retrospectivo. As variáveis avaliadas no estudo foram idade, resultado histológico e imuno-histoquímico da biópsia, análise da RM após QTN e análise histológica da peça cirúrgica, com cálculo do índice residual cancer burden. Os resultados da resposta radiológica pela RM foram comparados com a resposta patológica na peça cirúrgica (padrão ouro).
Resultados: Foram incluídos 310 tumores de 308 pacientes com média de idade de 47 anos (variação: 27 a 85 anos). A acurácia da RM foi 79%, com sensibilidade de 75%, especificidade de 83%, valor preditivo positivo de 75% e valor preditivo negativo de 83%. Estratificando-se por subtipo molecular, a detecção da resposta patológica pela RM obteve os melhores porcentuais de acerto no subtipo HER2 superexpresso, com sensibilidade e especificidade de 82% e 89%, respectivamente, seguido do subtipo triplo negativo, com sensibilidade e especificidade de 78% e 83%, respectivamente.
Conclusão: A RM demonstrou boa acurácia na predição de resposta patológica completa após QTN. A sensibilidade e o valor preditivo positivo foram mais altos nos subtipos triplo negativo e HER2 superexpresso.
Keywords: Breast neoplasms; Drug therapy, combination; Magnetic resonance imaging; Receptor, ErbB-2; Triple negative breast neoplasms.