San Antonio, TX—Ductal carcinoma in situ (DCIS) in itself is not dangerous, but some patients will eventually develop invasive breast cancer. Until recently, there was no way to predict which patients with DCIS were at high risk and required more aggressive treatment. Thus, many patients have been overtreated or undertreated.
Oncotype DX DCIS is a predictive tool that can be used to inform appropriate treatment selection according to risk level. This assay was validated with DCIS in a large population-based, real-world study presented at the 2014 San Antonio Breast Cancer Symposium.
A previous study with more narrow selection criteria validated Oncotype DX DCIS. “Our results confirm the ECOG E5914 results in a more diverse population,” explained lead investigator Eileen Rakovitch, MD, MSc, of the Sunnybrook Health Sciences Centre, University of Toronto, Ontario, 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.
The Assay
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 after treatment with breast-conservation surgery alone.
Oncotype DX DCIS categorizes results in a score ranging 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.
The study screened 1658 women diagnosed with pure DCIS and treated with breast-conservation surgery alone in Ontario, Canada; tissue samples for Oncotype DX DCIS analysis were available for 858 women, and 257 were excluded.
In the 571 women included in the primary study, at a median follow-up of 9.4 years, 100 cases of local recurrence were identified (57, invasive; 44, DCIS).
Applying the DCIS DX score retrospectively, the 10-year local recurrence risk 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.
“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 individuals weigh their own risk in making treatment decisions,” Dr Rakovitch said.
Oncotype DX DCIS is reimbursed by Medicare and by some private insurers.