title: Accuracy of MRI for treatment response assessment after taxane- and anthracycline-based neoadjuvant chemotherapy in HER2-negative breast cancer.
abstract: BACKGROUND
  Studies suggest that MRI is an accurate means for assessing tumor size after neoadjuvant chemotherapy (NAC). However, accuracy might be dependent on the receptor status of tumors. MRI accuracy for response assessment after homogenous NAC in a relative large group of patients with stage II/III HER2-negative breast cancer has not been reported before.
  
  
  METHODS
  250 patients from 26 hospitals received NAC (docetaxel, adriamycin and cyclophosphamide) in the context of the NEOZOTAC trial. MRI was done after 3 cycles and post-NAC. Imaging (RECIST 1.1) and pathological (Miller and Payne) responses were recorded. Accuracy measures were calculated and MRI and pathologically assessed tumor sizes were correlated. Tumor size over- and underestimation were quantified.
  
  
  RESULTS
  Accuracy of MRI for determining pathological complete response (pCR) was 76%. The ROC-curve of MRI response and pCR had an area under the curve value of 0.63 (95% C.I. 0.52-0.74). The correlation coefficient of MRI and histopathological tumor measurements was 0.46 (p < 0.001). Correlations were different for ER-positive (r = 0.40, p < 0.001) and ER-negative (r = 0.76, p < 0.001) breast tumors. MRI under- and overestimated the tumor size in 47% and 40% of all patients. In cases of substantial tumor size underestimation (>2 cm), surgical margins were more often tumor positive compared to the rest of the patients (33% vs.12%, p = 0.005).
  
  
  CONCLUSIONS
  MRI measurements correlated moderately with tumor size on the surgical specimen. Only in ER-negative breast tumors, MRI tumor sizes correlated sufficiently with residual tumor size on the pathological specimen. Therefore, post-NAC MRI should be interpreted with caution.
authors.affiliation: Department of Clinical Oncology, Leiden University Medical Center, The Netherlands; Department of Surgery, Leiden University Medical Center, The Netherlands. Electronic address: a.charehbili@lumc.nl.
authors.forename: A
authors.initials: A
authors.lastname: Charehbili
authors.affiliation: Department of Radiology, Leiden University Medical Center, The Netherlands.
authors.forename: M N
authors.initials: MN
authors.lastname: Wasser
authors.affiliation: Department of Pathology, Leiden University Medical Center, The Netherlands.
authors.forename: V T H B M
authors.initials: VT
authors.lastname: Smit
authors.affiliation: Department of Medical Statistics, Leiden University Medical Center, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Putter
authors.affiliation: Dutch Breast Cancer Research Group (BOOG), The Netherlands.
authors.forename: A E
authors.initials: AE
authors.lastname: van Leeuwen-Stok
authors.affiliation: Department of Surgery, Leiden University Medical Center, The Netherlands.
authors.forename: W M
authors.initials: WM
authors.lastname: Meershoek-Klein Kranenbarg
authors.affiliation: Department of Surgery, Leiden University Medical Center, The Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: Liefers
authors.affiliation: Department of Surgery, Leiden University Medical Center, The Netherlands.
authors.forename: C J H
authors.initials: CJ
authors.lastname: van de Velde
authors.affiliation: Department of Clinical Oncology, Leiden University Medical Center, The Netherlands.
authors.forename: J W R
authors.initials: JW
authors.lastname: Nortier
authors.affiliation: Department of Clinical Oncology, Leiden University Medical Center, The Netherlands.
authors.forename: J R
authors.initials: JR
authors.lastname: Kroep
mesh_terms: D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D019540:Area Under Curve; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D002277:Carcinoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D017024:Chemotherapy, Adjuvant; D003520:Cyclophosphamide / Q000008:administration & dosage; D004164:Diphosphonates / Q000627:therapeutic use; D000077143:Docetaxel; D004317:Doxorubicin / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000627:therapeutic use; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D012372:ROC Curve; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D043823:Taxoids / Q000008:administration & dosage; D016896:Treatment Outcome; D047368:Tumor Burden; D000077211:Zoledronic Acid
chemical_list: D003520:Cyclophosphamide; D004164:Diphosphonates; D000077143:Docetaxel; D004317:Doxorubicin; D007093:Imidazoles; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D043823:Taxoids; D000077211:Zoledronic Acid
keywords: Breast neoplasms; Magnetic resonance imaging; Neoadjuvant therapy; Surgery