title: Margin index: a useful tool for the breast surgeon?
abstract: BACKGROUND
  In breast conservation surgery (BCS) for breast cancer, the appropriate surgical margin is controversial. Margin index, a mathematical relationship between tumor size and closest margin, has been shown to be predictive of the probability of residual cancer after BCS for early stage breast cancer. We applied this tool to the same population of patients at our institution to evaluate its ability to predict residual disease after BCS.
  
  
  METHODS
  We retrospectively reviewed a prospectively maintained database of women undergoing BCS between 1980 and 2010 at the University of Pennsylvania. A total of 246 women underwent re-excision because of close margins. Average margin index between groups with and without residual disease in the re-excision specimen was compared using the Student t-test. A receiver operating curve was created using logistic regression to assess the overall diagnostic ability of the margin index on the presence or absence of residual disease.
  
  
  RESULTS
  Of patients who underwent re-excision, 29% of patients had residual disease. We analyzed several cutoff values for margin index, but none proved to be significant predictors of residual disease. Average margin index was significantly higher for patients without residual disease compared with patients with residual invasive cancer but not for patients with residual ductal carcinoma in situ.
  
  
  CONCLUSIONS
  In women undergoing BCS for early stage breast cancer at our institution, margin index was not predictive of the presence of residual cancer on re-excision. We hypothesize that the predictive ability of a margin index is likely limited by several factors including the presence of ductal carcinoma in situ and the location and extent of the close margin.
authors.affiliation: Department of Surgery, George Washington University Medical Center, Washington, District of Columbia. Electronic address: cedwards@mfa.gwu.edu.
authors.forename: Claire
authors.initials: C
authors.lastname: Edwards
authors.affiliation: Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Feng
authors.initials: F
authors.lastname: Gao
authors.affiliation: Division of Radiation Oncology, Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Gary M
authors.initials: GM
authors.lastname: Freedman
authors.affiliation: Department of Surgery, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Margenthaler
authors.affiliation: Division of Surgical Oncology, Rena Rowan Breast Center, Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Carla
authors.initials: C
authors.lastname: Fisher
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D016015:Logistic Models; D015412:Mastectomy, Segmental / Q000379:methods*; D008875:Middle Aged; D018365:Neoplasm, Residual; D012372:ROC Curve; D012189:Retrospective Studies
keywords: Breast cancer; Breast-conserving surgery; Lumpectomy; Radiation therapy; Surgical margins
references.citation: J Natl Cancer Inst Monogr. 1992;(11):19-25
references.pmid: 1627427
references.citation: J Natl Cancer Inst. 2000 Jul 19;92(14):1143-50
references.pmid: 10904087
references.citation: Mod Pathol. 2008 Jan;21(1):39-45
references.pmid: 17948023
references.citation: Int J Radiat Oncol Biol Phys. 2004 Sep 1;60(1):86-94
references.pmid: 15337543
references.citation: Br J Cancer. 2001 Jul 20;85(2):225-7
references.pmid: 11461081
references.citation: J Clin Oncol. 1996 May;14(5):1558-64
references.pmid: 8622072
references.citation: Eur J Cancer. 2010 Dec;46(18):3219-32
references.pmid: 20817513
references.citation: Am J Surg. 2002 Nov;184(5):383-93
references.pmid: 12433599
references.citation: J Surg Res. 2013 Sep;184(1):228-33
references.pmid: 23688789
references.citation: N Engl J Med. 2002 Oct 17;347(16):1227-32
references.pmid: 12393819
references.citation: Ann Surg Oncol. 2010 Feb;17(2):558-63
references.pmid: 19847566
references.citation: N Engl J Med. 2002 Oct 17;347(16):1233-41
references.pmid: 12393820
references.citation: Ann Surg. 2005 Apr;241(4):629-39
references.pmid: 15798465
references.citation: Hum Pathol. 2000 Apr;31(4):464-74
references.pmid: 10821494
references.citation: J Clin Oncol. 2000 Apr;18(8):1668-75
references.pmid: 10764427
references.citation: J Clin Oncol. 2009 Oct 20;27(30):4939-47
references.pmid: 19720914
references.citation: N Engl J Med. 1995 Apr 6;332(14):907-11
references.pmid: 7877647
references.citation: Ann Surg Oncol. 2012 Jan;19(1):207-11
references.pmid: 21638098
references.citation: Ann Surg Oncol. 2010 Oct;17(10):2696-701
references.pmid: 20422459
references.citation: Ann Surg Oncol. 2011 Oct;18(11):3155-9
references.pmid: 21947593
references.citation: Int J Radiat Oncol Biol Phys. 1999 Jul 15;44(5):1005-15
references.pmid: 10421533
references.citation: JAMA. 2012 Feb 1;307(5):467-75
references.pmid: 22298678