Radiologic complete response (rCR) in contrast-enhanced magnetic resonance imaging (CE-MRI) after neoadjuvant chemotherapy for early breast cancer predicts recurrence-free survival but not pathologic complete response (pCR)

Abstract

BackgroundPatients with early breast cancer (EBC) achieving pathologic complete response (pCR) after neoadjuvant chemotherapy (NACT) have a favorable prognosis. Breast surgery might be avoided in patients in whom the presence of residual tumor can be ruled out with high confidence. Here, we investigated the diagnostic accuracy of contrast-enhanced MRI (CE-MRI) in predicting pCR and long-term outcome after NACT.MethodsPatients with EBC, including patients with locally advanced disease, who had undergone CE-MRI after NACT, were retrospectively analyzed (n = 246). Three radiologists, blinded to clinicopathologic data, reevaluated all MRI scans regarding to the absence (radiologic complete remission; rCR) or presence (no-rCR) of residual contrast enhancement. Clinical and pathologic responses were compared categorically using Cohen’s kappa statistic. The Kaplan-Meier method was used to estimate recurrence-free survival (RFS) and overall survival (OS).ResultsOverall rCR and pCR (no invasive tumor in the breast and axilla (ypT0/is N0)) rates were 45% (111/246) and 29% (71/246), respectively. Only 48% (53/111; 95% CI 38–57%) of rCR corresponded to a pCR (= positive predictive value - PPV). Conversely, in 87% (117/135; 95% CI 79–92%) of patients, residual tumor observed on MRI was pathologically confirmed (= negative predictive value - NPV). Sensitivity to detect a pCR was 75% (53/71; 95% CI 63–84%), while specificity to detect residual tumor and accuracy were 67% (117/175; 95% CI 59–74%) and 69% (170/246; 95% CI 63–75%), respectively. The PPV was significantly lower in hormone-receptor (HR)-positive compared to HR-negative tumors (17/52 = 33% vs. 36/59 = 61%; P = 0.004). The concordance between rCR and pCR was low (Cohen’s kappa − 0.1), however in multivariate analysis both assessments were significantly associated with RFS (rCR P = 0.037; pCR P = 0.033) and OS (rCR P = 0.033; pCR P = 0.043).ConclusionPreoperative CE-MRI did not accurately predict pCR after NACT for EBC, especially not in HR-positive tumors. However, rCR was strongly associated with favorable RFS and OS.Electronic supplementary materialThe online version of this article (10.1186/s13058-018-1091-y) contains supplementary material, which is available to authorized users.

<p>Prediction of Pathologic Complete Response by Ultrasonography and Magnetic Resonance Imaging After Neoadjuvant Chemotherapy in Patients with Breast Cancer</p>

“…The moderate accuracy of all three imaging modalities indicates that they are not reliable enough to predict pCR in a clinical setting, as was concluded in previous studies. 22,25,32 As is indicated in other studies, 15,17,21,28,33 this study showed that the diagnostic performance of US or MRI varied between different histological and molecular subtypes. This may be correlated with the different pCR rates between these groups.…”

“…A recent study has reported that there was little difference between different pCR definitions in the diagnostic performance of MRI. 17 However, our present study found that different definitions of pCR led to differences in some diagnostic indicators for US, MRI, and US+MRI. Thus, these discrepancies should be noted when it comes to comparisons between these studies.…”

“…Numerous studies on the diagnostic performance of imaging to evaluate the primary tumor response to NAC in breast cancer have been published. However, the definitions of pCR varied from the absence of residual invasive cancer with or without cancer in situ (ypT0/is) 14,17,21,24 to the absence of residual invasive and noninvasive cancer (ypT0) 15,16,25 in the primary tumor area. What is more, some studies defined the presence of a pCR as positivity, 16,17,21 whereas others considered the presence of residual tumor as positivity 14,15,22,23,25 when they analyzed the diagnostic performance of imaging with sensitivity, specificity, accuracy, PPV, and NPV, and so on.…”

“…13 However, the accuracy of MRI in predicting pCR in breast cancer after NAC varied in different researches. [14][15][16][17] Furthermore, the accuracy between MRI and US is uncertain, 18 though the latter is often an alternative tool to evaluate tumor response. Therefore, the purpose of this retrospective study was to compare the diagnostic performance of US, MRI, and the combination of US and MRI in predicting pCR in primary breast cancer after NAC.…”

MRI does not predict pathologic complete response after neoadjuvant chemotherapy for breast cancer

“…A recent study demonstrated a strong association between rCR on contrast‐enhanced MRI after NAC and relapse‐free and overall survival …”