SABCS 2014: Oncotype DX DCIS Score Reliably Predicts Breast Cancer Recurrence in Patients With DCIS
Ductal carcinoma in situ (DCIS), which accounts for 30% of all newly diagnosed breast cancer, is actually a precancerous lesion. A proportion of patients will have progression to invasive breast cancer, but up until recently, it has not been possible to identify which patients require further treatment to prevent recurrence.
Oncotype DX DCIS is a 12-panel gene test with a scoring system that categorizes cancers as low, intermediate, or high risk for local recurrence over 10 years following treatment with breast-conserving surgery alone. A large population-based study presented at the 2014 San Antonio Breast Cancer Symposium validated Oncotype DX DCIS in a diverse population of women with DCIS (Abstract S5-04).
Oncotype DX DCIS Assay
The current study is important because the ECOG E5914 study that showed Oncotype DX DCIS was predictive of local recurrence was based on only a select population of women. “Our results confirm the ECOG E5914 results in a more diverse population,” explained lead author Eileen Rakovitch, MD, Sunnybrook Health Sciences Centre, University of Toronto, Canada. “
“This is the first biomarker assay to provide individualized estimates of the risk of local recurrence in women treated by breast conservation alone. The DCIS Score can be used for discussions between patients and physicians to decide upon a course of further treatment. Hopefully this will improve individualized management of DCIS and reduce overtreatment of women at low risk of recurrence and reduce undertreatment of women at higher risk of recurrence,” Dr. Rakovitch stated.
Oncotype DX DCIS is expressed in variables from 0 to 100. A DCIS Score of < 39 indicates low risk for recurrence, 39 to 54 indicates intermediate risk, and ≥ 55 indicates high risk.
Study Details
A population-based study was undertaken to validate the score in women diagnosed with pure DCIS and treated with breast-conserving surgery alone in Ontario, Canada. Of 1,658 cases that met these criteria, tissue blocks were available for 858 and 257 were excluded, leaving a study cohort of 571 individuals. At a median follow-up of 9.6 years, 100 cases of local recurrence were identified (57 invasive and 44 DCIS).
Using the Oncotype DX DCIS score retrospectively, the 10-year risk of local recurrence was estimated at 12.7% for low-risk patients, 27.8% for intermediate-risk patients, and 33% for high-risk patients. The score also predicted invasive recurrence and DCIS recurrence, she said.
“Comparing the Ontario Cohort with the more highly selected E5194 cohort, outcomes were remarkable similar,” Dr. Rakovitch said. “The Oncotype DX DCIS improves risk stratification and provides individualized estimates of risk that will help clinicians and patients better understand risk of recurrence and will help individuals weigh their own risk in making treatment decisions.”
The cost of Oncotype DX DCIS is covered by Medicare and some private insurers.
Funding for the study was provided by grants from the Canadian Cancer Society Research Institute and a Genomic Health. Dr. Rakovitch reported no potential conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
