title: Tumor Size of Invasive Breast Cancer on Magnetic Resonance Imaging and Conventional Imaging (Mammogram/Ultrasound): Comparison with Pathological Size and Clinical Implications.
abstract: OBJECTIVE
  In Landspitali University Hospital, magnetic resonance imaging is used non-selectively in addition to mammogram and ultrasound in the preoperative assessment of breast cancer patients. The aim of this study was to assess invasive tumor size on imaging, compare with pathological size and evaluate the impact of magnetic resonance imaging on the type of surgery performed.
  
  
  METHODS
  All women with invasive breast cancer, diagnosed in Iceland, between 2007 and 2009 were reviewed retrospectively. In all, 438 of 641 (68%) patients diagnosed had preoperative magnetic resonance imaging. Twelve patients treated with neoadjuvant chemotherapy were excluded and 65 patients with multifocal or contralateral disease were assessed separately.
  
  
  RESULTS
  Correlations between microscopic and radiologic tumor sizes were relatively weak. All imaging methods were inaccurate especially for large tumors, resulting in an overall underestimation of tumor size for these tumors. Magnetic resonance imaging under- and overestimated pathological tumor size by more than 10 mm in 16/348 (4.6%) and 26/348 patients (7.5%), respectively. In 19 patients (73%), overestimation of size was seen exclusively on magnetic resonance imaging. For tumors under- or overestimated by magnetic resonance imaging, the mastectomy rates were 56% and 65%, respectively, compared to an overall mastectomy rate of 43%. Of 51 patients diagnosed with multifocal disease on pathology, 19 (37%) were diagnosed by mammogram or ultrasound and 40 (78%) by magnetic resonance imaging resulting in a total detection rate of 84% (43 patients). Fourteen (3%) patients were diagnosed preoperatively with contralateral disease. Of those tumors, all were detected on magnetic resonance imaging but seven (50%) were also detected on mammogram or ultrasound or both.
  
  
  CONCLUSIONS
  Our results suggest that routine use of magnetic resonance imaging may result in both under- and overestimation of tumor size and increase mastectomy rates in a small proportion of patients. Magnetic resonance imaging aids in the diagnosis of contralateral and multifocal disease.
authors.affiliation: 1 Department of Surgery, Landspitali University Hospital, Reykjavik, Iceland.|2 Department of Surgery, Lund University Hospital, Lund, Sweden.
authors.forename: K H
authors.initials: KH
authors.lastname: Haraldsdóttir
authors.affiliation: 1 Department of Surgery, Landspitali University Hospital, Reykjavik, Iceland.
authors.forename: Þ
authors.initials: Þ
authors.lastname: Jónsson
authors.affiliation: 3 Department of Radiology, Icelandic Cancer Society, Reykjavik, Iceland.
authors.forename: A B
authors.initials: AB
authors.lastname: Halldórsdóttir
authors.affiliation: 2 Department of Surgery, Lund University Hospital, Lund, Sweden.
authors.forename: K-G
authors.initials: KG
authors.lastname: Tranberg
authors.affiliation: 1 Department of Surgery, Landspitali University Hospital, Reykjavik, Iceland.
authors.forename: K S
authors.initials: KS
authors.lastname: Ásgeirsson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D018275:Carcinoma, Lobular / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D000066491:Clinical Decision-Making / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008327:Mammography; D008408:Mastectomy; D008875:Middle Aged; D011300:Preoperative Care / Q000379:methods*; D012189:Retrospective Studies; D047368:Tumor Burden; D016217:Ultrasonography, Mammary
keywords: Breast cancer; breast conservation surgery; magnetic resonance imaging; mastectomy; oncoplastic surgery; tumor size