The Oncotype DX breast cancer assay for ductal carcinoma in situ (DCIS) is a strong and significant predictor of 10-year risk of recurrence in women with DCIS, according to a study presented at the CTRC-AACR San Antonio Breast Cancer Symposium (SABCS) held in December 2011. It is the first clinically validated genomic assay to predict risk of local recurrence for women with DCIS, and it is now available from Genomic Health.
The assay utilizes a panel of 12 genes to predict the risk of local recurrence with DCIS and invasive breast cancer over the next 10 years. The score derived from the assay will be useful for guiding decision making in women with DCIS treated with local excision with or without adjuvant hormonal therapy. The score can identify low-risk patients who can forgo further treatment, as well as high-risk patients who require more aggressive therapy; it can also identify intermediate-risk patients, who comprise a small but challenging group for treatment decisions. Some insurance plans cover the DCIS assay, and Genomic Health has an assistance program to help patients gain reimbursement from plans that may not cover the test.
“The DCIS score [derived from the multigene RT-PCR assay] can be used to quantify an individual patient’s 10-year risk of developing a recurrence. The score provides independent information on recurrence risk beyond clinical and pathological variables. We are not just reinventing the wheel here,” said lead author Lawrence J. Solin, MD, chair of radiation oncology at Einstein Medical Center in Philadelphia, Pennsylvania.
The increased incidence of DCIS is attributed to increased use of screening mammography finding cancers at very early stages. The majority of patients diagnosed with DCIS will not have a recurrence. However, until now there has been no validated method to predict recurrence, so all patients with DCIS typically receive radiation and/or hormonal therapy if they are estrogen receptor positive.
The validation study presented at SABCS was based on paraffin-embedded tumor samples from 327 patients enrolled in ECOG 5194, a multi-institutional study of patients with low-, intermediate-, or high-grade DCIS who underwent breast conservation surgery with wide negative margins but did not receive radiation; treatment with tamoxifen was optional.
The Oncotype DX DCIS multigene assay was used to classify patients as low, intermediate, or high risk according to prespecified characteristics. Solin noted that about 75% were low risk.
The DCIS score was a significant and strong predictor of local recurrence (P = .02) and invasive local recurrence (P = .01) over a 10-year period.
The cost of the DCIS test will be similar to that of the Oncotype DX 21-gene assay. Solin said the cost should be offset by the ability to avoid radiation and further treatment in low-risk DCIS.
“Treatment selection is not clear for intermediate-risk patients, but this test allows us to provide information on their individual risk level. The numbers of patients in the intermediate-risk group are actually very small. Most patients with DCIS are low risk,” Solin said.