There is no relevant literature specifically comparing the performance of DBT to mammography after initiation or completion of NAC. FDG-PET/CT Skull Base to Mid-Thigh Because of its relatively low specificity, PET/CT is not routinely used for posttreatment imaging of the primary breast tumor and is typically only used in combination with other imaging modalities to monitor treatment response [52-54]. Two meta-analyses found posttreatment PET/CT sensitivities of 77% to 84% and specificities of 66% to 78% for predicting response to therapy [52,54]. In a study by Bassa et al [55], PET was able to accurately predict residual disease in only 75% of cases, compared with 88% for US. However, PET may have use in assessing early response to therapy, with a study in 47 patients showing that a >50% to 60% reduction in FDG uptake after one cycle of therapy correlated with a pCR [56]. PET imaging may be more helpful for certain tumor subtypes. Three studies showed that PET/CT can reliably detect early response and predict residual disease in HER2/neu-positive tumors [57-59], and a <42% decrease in radioisotope uptake in triple-negative tumors correlates with poor response and outcome [60]. Lobular cancers are less FDG avid, making assessment challenging [61,62]. Mammography Diagnostic Although mammography and US are reliable for determining tumor size at diagnosis [11-15], changes within the tumor, secondary to NAC, may be difficult to evaluate after treatment is initiated. It is well known that tumoral changes related to necrosis, fragmentation, and fibrosis make it difficult for mammography, DBT, and US to accurately determine residual tumor burden [43,44]. In a retrospective study of 445 patients who underwent NAC, mammography was 94% sensitive and 50% specific for predicting residual disease in the breast. In cases presenting as mass lesions, most masses (95%) decreased in mammographic size with treatment.
Monitoring Response to Neoadjuvant Systemic Therapy for Breast Cancer. There is no relevant literature specifically comparing the performance of DBT to mammography after initiation or completion of NAC. FDG-PET/CT Skull Base to Mid-Thigh Because of its relatively low specificity, PET/CT is not routinely used for posttreatment imaging of the primary breast tumor and is typically only used in combination with other imaging modalities to monitor treatment response [52-54]. Two meta-analyses found posttreatment PET/CT sensitivities of 77% to 84% and specificities of 66% to 78% for predicting response to therapy [52,54]. In a study by Bassa et al [55], PET was able to accurately predict residual disease in only 75% of cases, compared with 88% for US. However, PET may have use in assessing early response to therapy, with a study in 47 patients showing that a >50% to 60% reduction in FDG uptake after one cycle of therapy correlated with a pCR [56]. PET imaging may be more helpful for certain tumor subtypes. Three studies showed that PET/CT can reliably detect early response and predict residual disease in HER2/neu-positive tumors [57-59], and a <42% decrease in radioisotope uptake in triple-negative tumors correlates with poor response and outcome [60]. Lobular cancers are less FDG avid, making assessment challenging [61,62]. Mammography Diagnostic Although mammography and US are reliable for determining tumor size at diagnosis [11-15], changes within the tumor, secondary to NAC, may be difficult to evaluate after treatment is initiated. It is well known that tumoral changes related to necrosis, fragmentation, and fibrosis make it difficult for mammography, DBT, and US to accurately determine residual tumor burden [43,44]. In a retrospective study of 445 patients who underwent NAC, mammography was 94% sensitive and 50% specific for predicting residual disease in the breast. In cases presenting as mass lesions, most masses (95%) decreased in mammographic size with treatment.