title: Using proliferative markers and Oncotype DX in therapeutic decision-making for breast cancer: the B.C. experience.
abstract: BACKGROUND
  Proliferative scoring of breast tumours can guide treatment recommendations, particularly for estrogen receptor (er)-positive, her2-negative, T1-2, N0 disease. Our objectives were to □ estimate the proportion of such patients for whom proliferative indices [mitotic count (mc), Ki-67 immunostain, and Oncotype dx (Genomic Health, Redwood City, CA, U.S.A.) recurrence score (rs)] were obtained.□ compare the indices preferred by oncologists with the indices available to them.□ correlate Nottingham grade (ng) and its subcomponents with Oncotype dx.□ assess interobserver variation.
  
  
  METHODS
  All of the er-positive, her2-negative, T1-2, N0 breast cancers diagnosed from 2007 to 2011 (n = 5110) were linked to a dataset of all provincial breast cancers with a rs. A 5% random sample of the 5110 cancers was reviewed to estimate the proportion that had a mc, Ki-67 index, and rs. Correlation coefficients were calculated for the rs with ng subcomponent scores. Interobserver variation in histologic grading between outside and central review pathology reports was assessed using a weighted kappa test.
  
  
  RESULTS
  During 2007-2011, most cancers were histologically graded and assigned a mc; few had a Ki-67 index or rs. The ng and mc were significantly positively correlated with rs. The level of agreement in histologic scoring between outside and central pathology reports was good or very good. Very few cases with a low mc had a high rs (1.8%).
  
  
  CONCLUSIONS
  Patients with low ng and mc scores are unlikely to have a high rs, and thus are less likely to benefit from chemotherapy. In the context of limited resources, that finding can guide clinicians about when a rs adds the most value.
authors.affiliation: Department of Radiation Oncology, BC Cancer Agency, Vancouver Centre, BC;
authors.forename: E
authors.initials: E
authors.lastname: Baxter
authors.affiliation: Department of Cancer Surveillance and Outcomes, BC Cancer Agency, Vancouver Centre, BC;
authors.forename: L
authors.initials: L
authors.lastname: Gondara
authors.affiliation: Department of Medical Oncology, BC Cancer Agency, Vancouver Centre, BC;
authors.forename: C
authors.initials: C
authors.lastname: Lohrisch
authors.affiliation: Department of Medical Oncology, BC Cancer Agency, Vancouver Centre, BC;
authors.forename: S
authors.initials: S
authors.lastname: Chia
authors.affiliation: Department of Medical Oncology, BC Cancer Agency, Vancouver Centre, BC;
authors.forename: K
authors.initials: K
authors.lastname: Gelmon
authors.affiliation: Department of Pathology, BC Cancer Agency, Vancouver Centre, BC.
authors.forename: M
authors.initials: M
authors.lastname: Hayes
authors.affiliation: Department of Medical Oncology, BC Cancer Agency, Vancouver Centre, BC;
authors.forename: A
authors.initials: A
authors.lastname: Davidson
authors.affiliation: Department of Radiation Oncology, BC Cancer Agency, Vancouver Centre, BC;
authors.forename: S
authors.initials: S
authors.lastname: Tyldesley
keywords: Breast cancer; proliferative markers