Analysis of complete response by MRI following neoadjuvant chemotherapy predicts pathological tumor responses differently for molecular subtypes of breast cancer

Abstract

Abstract. In the present study, clinical tumor response following neoadjuvant chemotherapy (NAC) was diagnosed by magnetic resonance imaging (MRI) and clinicopathological factors, including molecular subtypes at baseline, were analyzed for correlations with pathological tumor responses. In addition, clinicopathological factors were analyzed for a correlation with the MRI capacity to predict pathological complete response (pCR). Clinical tumor response evaluated by MRI following NAC was determined as a clinical CR (cCR) or a residual tumor. cCR was confirmed if no gadolinium enhancement or an enhancement equal to or less than that of glandular tissue was observed in any phase of the MRI. Pathological tumor responses following NAC were classified into grades 0 (no change) to 3 (no residual invasive cancer) according to criteria of the Japanese Breast Cancer Society. pCR was defined as grade 3 in the present study. Of 264 cases of invasive breast cancer in 260 patients (4 synchronous bilateral breast cancer cases), 59 (22%) were diagnosed by MRI following NAC as cCR and 98 (37%) were pathologically diagnosed as pCR. In terms of predicting pCR by MRI, the sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were 44, 90, 73, 73 and 73%, respectively. Tumor size, hormone receptor status, human epidermal growth factor receptor 2 (HER2) status, molecular subtype and histological type were significantly correlated with pathological tumor responses. pCR rates increased in the following order: luminal/HER2-negative (14%), luminal/HER2-positive (32%), triple-negative (46%) and non-luminal/HER2-positive (73%) tumors. Sensitivity and specificity were the highest (60 and 100%, respectively) in triple-negative tumors. PPV decreased in the following order: triple-negative (100%), non-luminal/HER2-positive (92%), luminal/HER2-positive (46%) and luminal/HER2-negative (33%) tumors. In conclusion, MRI evaluation is useful for predicting pCR following NAC, particularly for triple-negative tumors.

Breast Cancer Subtype Influences the Accuracy of Predicting Pathologic Response by Imaging and Clinical Breast Exam After Neoadjuvant Chemotherapy

“…Recent studies have shown that the accuracy of imaging in clinical response evaluation varies by breast cancer subtype according to HR and HER2 status (11)(12)(13)(14)(15)(16)(17)(18)(19). Specifically, MRI more accurately predicts pathologic response in HR-negative subtypes rather than HRpositive stubtypes (11,(16)(17)(18)(19).…”

MRI predicts pathologic complete response in HER2-positive breast cancer after neoadjuvant chemotherapy

“…In literature, a wide spread of NPVs has been described in the HER2-positive subtype ranging from 0 to 95% in studies providing clear definitions of accuracy measurements and including C25 patients [6,7,9,10,14,17,18]. This variation Fig.…”

Accuracy of MRI for Prediction of Response to Neo-Adjuvant Chemotherapy in Triple Negative Breast Cancer Compared to Other Molecular Types

“…Whilst the definition of pCR varies in different studies, investigators have shown that accuracy of MRI for predicting pCR varies with different subtypes [5,6,23]. Loo et al [4] found excellent correlation between residual tumour size on MRI and post treatment surgical size for TN and HER2+ subtypes, but not for Luminal cancers.…”

“…They found highest negative predictive value (the ability to predict pCR) with TN and HER2+ cancers. Hayashi et al [5] evaluated 264 breast cancers and found highest discrepancy between imaging and pathology for Luminal cancers and cautioned when interpreting MR images in Luminal cancers, with underestimation of disease in two-thirds of them. In our study, MR underestimated disease in 17 (58.6%) Luminal cancers.…”

“…Patients with pathological complete response (pCR) following NAC have favourable prognosis [4][5][6]. Previous studies have demonstrated that triple negative (TN; ER-, PR-, HER2-) breast cancer is a distinct entity and behaves differently to other molecular subtypes of breast cancer, especially with respect to attainment of pathological complete response (pCR) to NAC and imaging presentation on pre chemotherapy MRI [7][8][9][10][11][12].…”