Magnetic resonance imaging as a predictor of pathologic response in patients treated with neoadjuvant systemic treatment for operable breast cancer

Abstract

Background Increased pathologic complete response (pCR) rates observed with neoadjuvant chemotherapy (NCT) for some subsets of patients with invasive breast cancer has prompted interest in whether patients with pCR can be identified preoperatively and potentially spared the morbidity of surgery. This multicenter retrospective study was performed to estimate the accuracy of preoperative MRI in predicting pCR in the breast. Methods MRI at baseline and after completion of NCT plus data regarding pathologic response was collected retrospectively from 746 women treated at 8 institutions between 2002–2011. Tumors were characterized by immunohistochemical (IHC) phenotype into 4 categories based on receptor expression: hormone (estrogen & progesterone) receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2) negative (n=327), HR-positive, HER2-positive, (n=148), HR-negative, HER2-positive, (n=101), and triple-negative (HR-negative, HER2-negative, n=155). 194/249 (78%) patients with HER2-positive tumors received trastuzumab. Univariate and multivariate analyses of factors associated with radiographic complete response (rCR) and pCR were performed. Results rCR and pCR for total group were 182/746 (24%) and 179/746 (24%), respectively, with the highest rate of pCR seen among triple-negative (57/155; 37%) and HER2 positive (38/101; 38%) subtypes. Overall accuracy of MRI for pCR prediction was 74%. Sensitivity, NPV, PPV, and accuracy differed significantly among tumor subtypes, with the greatest NPV in the TN (60%) and HER2 positive (62%) subtypes. Conclusion Overall accuracy of MRI for predicting pCR in invasive breast cancer patients receiving NCT was 74%. MR performance differed among subtypes possibly influenced by differences in pCR rates between groups. Future studies will determine whether MRI in combination with directed core biopsy improves predictive value for pathologic response.

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

“…This may be due to small number of HER+ cancers in our group. Our results are in agreement with a study by De Los Santos [23], who evaluated 475 Luminal cancers, 150 TN cancers and 101 HER2+ cancers. They found highest negative predictive value (the ability to predict pCR) with TN and HER2+ cancers.…”

“…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.…”

The impact of preoperative breast MRI on the surgical management of newly diagnosed non metastatic breast cancers

“…Results were reported in accordance with Breast Imaging Reporting and Data System® (BI-RADS®) initiative, instituted by the ACR(8) and corroborated with ultrasonography of the breast and axillary region on Philips 5000 ultrasound system using multi-frequency linear transducer (4)(5)(6)(7)(8)(9)(10)(11). Clinical staging (AJCC Cancer Staging Manual, 7th edition(9)) was done after staging workup, following core needle biopsy (22 G Bard Max-core) of the suspicious lesions and a protocol based treatment was planned.…”

“…(5) A wider excision when an adjacent lesion or more extensive primary lesion was detected but breast conservation was still possible. (6) Detection of an otherwise undetected lesion in the opposite breast that resulted in contralateral surgery.…”

“…However, significant controversies still exist regarding its use as a preoperative tool. Preoperative MRI in assessment of response to NAC had superior sensitivity compared to mammography and ultrasound in invasive breast cancers (6), however had no effect on rates of reoperation (7). In view of lack of guidelines on indications of preoperative MR imaging of early invasive breast cancers, we conducted a study to determine the impact of preoperative breast magnetic resonance imaging on the surgical management of newly diagnosed non metastatic breast cancers.…”