Diagnostic Accuracy of MRI in Evaluating Response After Neoadjuvant Systemic Therapy in Operable Breast Cancer

Abstract

Background Neoadjuvant chemotherapy (NAC) is an important step in the treatment of various types of breast cancer by downsizing the tumor to make it operable. Determining disease extent after NAC is essential for accurate surgical planning. MRI has been the gold standard for detecting tumors that are usually difficult to detect on ultrasound or mammography. However, the use of MRI after NAC is controversial. Therefore, we aimed to evaluate the diagnostic accuracy of post-NAC MRI in the detection of residual disease preoperatively and to investigate the factors associated with pathological complete response (pCR). Methodology This retrospective review study was approved by the institutional review board with waiving of the informed consent. A total of 90 charts between January 2016 and January 2019 were reviewed. Baseline lesion size was measured as the maximal diameter in a single dimension by pretreatment MRI. To assess the diagnostic accuracy of MRI in detecting residual disease, we used two different definitions of pCR in the breast. The first is the resolution of both invasive disease and ductal carcinoma in situ. The second is the resolution of the invasive disease only. As a secondary objective of the study, we assessed the association between different patients’ characteristics and both MRI and pathologic response using univariate and multivariate analysis. Results A total of 52 women (mean age: 47.4 years; range: 28-74) with 56 breast masses were eligible for the study. Complete MRI response was noted in 22 (39%) masses. pCR was achieved in 14 (25%) and 25 (44.6%) masses using the first and second pCR definitions, respectively. The negative predictive value (NPV) and overall accuracy of MRI for detecting residual disease were 50% and 75%, respectively, using the first pCR definition. With the second pCR definition, NPV and accuracy were 77.3% and 76.8%, respectively. Positive axillary lymph nodes were the only significant factor associated with incomplete MRI and pathological responses. Conclusions MRI NPV for residual disease was higher with the second pCR definition; however, overall accuracy was not different. MRI accuracy in detecting residual disease after NAC is not adequate to replace pathological assessment.

The Role of MRI in Assessing Residual Breast Cancer After Neoadjuvant Chemotherapy

“…33 It was found that the accuracy of MRI in detecting the residual disease after NAC differs according to the pCR definition and is higher when considering the absence of the invasive disease only. 34 It was also found that underestimation of the residual disease is more common in non-mass-forming lesions than in mass-forming lesions. 35 Non-mass lesions can manifest as small areas of patchy enhancement, and the differentiation between these areas and areas of nonmalignant enhancement may be difficult.…”

The Role of Ultrasound Features in Predicting the Breast Cancer Response to Neoadjuvant Chemotherapy

“…Radiology studies continue to demonstrate inconsistencies in the imaging features as predictors of pCR. A recent survey of MRI imaging proved that MRI post-NACT remains inaccurate in replacing pCR [23]. On the other hand, studies have shown that tumor grade and hormonal status play a role in pCR rates.…”

The Radiologist at the Center of Breast Conservation in the Management of Breast Cancer: A Case-Based Narrative Review of the Literature

“…Therefore, WL was done for the non-palpable microcalcifications identified on her post-NAC mammograms by the Attending Radiologist (ADO). While MRI is usually the imaging modality of choice to monitor response to neoadjuvant therapy [30], mammography or ultrasound guidance is usually preferred for WL [27]. Extensive lesions and calcifications, especially those that exceed the borders of a mass, frequently require mammographic guidance and multiple wires for bracketing [27,31,32].…”