title: Unique characteristics and failure patterns of metaplastic breast cancer in contrast to invasive ductal carcinoma: a retrospective multicenter case-control study (KROG 13-07).
abstract: BACKGROUND
  This retrospective study was performed to investigate the need for management modification in MBC according to evaluation of characteristics and failure patterns compared with IDC.
  
  
  METHODS
  We performed this multicenter study taking MBC and randomly assigned IDC cases matched for age (± 3 years), pathologic stage (T and N), locoregional treatment methods (surgery with or without radiation therapy), and period of treatment (± 6 months) that occurred from January 1999 to November 2011 in the 6 institutions of the Korean Radiation Oncology Group.
  
  
  RESULTS
  A total of 144 female MBC patients were enrolled. The median follow-up was 51 months (range, 1-186 months). The rates of positivity for estrogen receptor (P < .001), progesterone receptor (P < .001), and HER2 (P = .007) were significantly lower in MBC patients. During follow-up, recurrence developed in 22 (15.3%) MBC and 6 (4.2%) IDC patients (P = .002). The median time to recurrence of MBC and IDC was 15 months and 24 months, respectively. Most instances of recurrence in MBC developed in the triple-negative (TN) subgroup (TN-MBC). In particular, locoregional recurrence developed exclusively in the TN-MBC subgroup. In the TN-MBC subgroup, the number of risk factors (pT2-3, N1-3) was related to significant differences in overall survival (P = .001) and recurrence-free survival (P < .001).
  
  
  CONCLUSIONS
  The MBC patients had a higher rate of TN, poorer differentiation, and a higher recurrence rate than did the IDC patients. Considering the unique characteristics and failure patterns, it is necessary to modify the current management guidelines for MBC.
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jeong Il
authors.initials: JI
authors.lastname: Yu
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. Electronic address: doho.choi@samsung.com.
authors.forename: Doo Ho
authors.initials: DH
authors.lastname: Choi
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Seung Jae
authors.initials: SJ
authors.lastname: Huh
authors.affiliation: Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Sung Ja
authors.initials: SJ
authors.lastname: Ahn
authors.affiliation: Department of Pathology, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Ji Shin
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Kyung Hwan
authors.initials: KH
authors.lastname: Shin
authors.affiliation: Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Youngmee
authors.initials: Y
authors.lastname: Kwon
authors.affiliation: Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Yong Bae
authors.initials: YB
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Chang-Ok
authors.initials: CO
authors.lastname: Suh
authors.affiliation: Department of Radiation Oncology, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Surgery, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea.
authors.forename: Jihyoung
authors.initials: J
authors.lastname: Cho
authors.affiliation: Department of Radiation Oncology, Seoul National University Bundang Hospital, Gyeonggi, Korea.
authors.forename: In Ah
authors.initials: IA
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, St Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
authors.forename: Jong Hoon
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Won
authors.initials: W
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000401:mortality / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008679:Metaplasia; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality*; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D064726:Triple Negative Breast Neoplasms / Q000401:mortality / Q000473:pathology*; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor
keywords: Case-control study; Invasive ductal carcinoma; Metaplastic breast cancer; Pattern of failure; Prognostic factor