title: Immunohistochemical assessment of Ki67 with antibodies SP6 and MIB1 in primary breast cancer: a comparison of prognostic value and reproducibility.
abstract: OBJECTIVE
  To compare SP6 and MIB1 antibodies for assessment of Ki67 in primary breast cancer with regard to prognostic value and reproducibility.
  
  
  RESULTS
  A cohort of 237 premenopausal women with node-negative breast cancer, mainly (87%) not treated with adjuvant systemic therapy, was used. Assessment of Ki67 (SP6 and MIB1) was performed on tissue microarray by three different investigators. The seventh decile was applied for cut-off. Distant disease-free survival (DDFS) was chosen as endpoint and the follow-up was restricted to 5 years. Eighty-nine per cent of the samples were classified into the same proliferation group, irrespective of antibody used. For both antibodies, high Ki67 was associated with inferior DDFS in univariable analyses (SP6: HR 2.5, P = 0.01; and MIB1: HR 2.8, P = 0.004), but failed to reach statistical significance for DDFS in multivariable analyses adjusted for HER2, age, and tumour size (SP6: HR 2.0, P = 0.074; and MIB1: HR 2.2, P = 0.058). The agreement between different assessors was somewhat higher for MIB1 than for SP6 (κ 0.83-0.88 versus 0.72-0.77).
  
  
  CONCLUSIONS
  SP6 was not superior to MIB1, but the two antibodies were comparable in the assessment of Ki67. Both MIB1 and SP6 could therefore be considered for prognostic use in primary breast cancer.
authors: Department of Oncology, Ryhov County Hospital, Jönköping, Sweden; Division of Oncology and Pathology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden.
authors: Maria
authors: M
authors: Ekholm
authors: Sanda
authors: S
authors: Beglerbegovic
authors: Dorthe
authors: D
authors: Grabau
authors: Kristina
authors: K
authors: Lövgren
authors: Per
authors: P
authors: Malmström
authors: Linda
authors: L
authors: Hartman
authors: Mårten
authors: M
authors: Fernö
mesh_terms: D000328:Adult; D000368:Aged; D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D053208:Kaplan-Meier Estimate; D019394:Ki-67 Antigen / Q000032:analysis*; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D015203:Reproducibility of Results; D046888:Tissue Array Analysis
chemical_list: D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; C440408:MIB-1 antibody
keywords: Ki67 antigen; MIB1; SP6; breast neoplasms; cell proliferation; prognosis; reproducibility of results