A Prospective Cohort Study to Evaluate the Oncotype DX® Test in Early Stage Breast Cancer (ONCOTYPEDX)

• Change in treatment recommendation [ Time Frame: One month ] [ Designated as safety issue: No ]
  The primary outcome is the change in treatment recommendation by the oncologist and the change in treatment preference of the patient.
  
  

• Association between Oncotype DX® RS with other estimated risk calculations [ Time Frame: One month ] [ Designated as safety issue: No ]
  The level of association between the Oncotype DX® RS with estimated recurrence risk calculated by Adjuvant! Online, as well as with traditional factors including tumor size, grade, and HER2 neu.
  
  
• Change in patient decisional conflict [ Time Frame: One month ] [ Designated as safety issue: No ]
  The change in the level of patient decisional conflict measured by the Decisional Conflict Scale (DCS). Additionally, the DCS has three subscales: uncertainty, effective decision making, and factors contributing to uncertainty. The change in each of these subscales will also be measured.
  
  
• Robustness of economic model of sequential Adjuvant! Online followed by Oncotype DX®. [ Time Frame: 6 months ] [ Designated as safety issue: No ]
  To determine the robustness of the economic model of sequential Adjuvant! Online followed by Oncotype DX®.
  
  

The evidence supporting the adoption of Oncotype DX® is relatively weak by the criteria used by the Ontario Health Technology Advisory Committee (OHTAC). There is only one small published prospective study that reports on Oncotype DX® changing clinical management. The economic models that estimated the potential advantages of using an Oncotype DX® guided treatment strategy may have overestimated the benefits because they assumed that all patients with tumors >1cm in the absence of Oncotype DX® testing would receive chemotherapy in addition to tamoxifen, and that the magnitude of benefit with chemotherapy over tamoxifen is relatively large, i.e. reduces recurrence risk by 74% and associated with an absolute benefit of 28%. (The benefit comes from one trial and is applied to all patients). It is estimated that there are about 3,300 incident cases with node negative, ER positive, HER2 neu negative tumors annually in Ontario, it is important to evaluate the adoption of this test for decision making in Ontario.