A new 12-gene assay for predicting risk of recurrence for patients with ductal carcinoma in situ (DCIS).
Lawrence J. Solin, MD
A new 12-gene assay for predicting risk of recurrence for patients with ductal carcinoma in situ (DCIS) was validated by a study presented at the CTRC-AACR San Antonio Breast Cancer Symposium, and the test (developed by Genomic Health) will be available for clinical use in a matter of weeks. Test results can be used to identify low-risk patients who do not require further radiation, as well as high-risk patients who should be treated more aggressively.
“The DCIS score [derived from the multigene RT-PCR assay] can identify patients at low, intermediate, and high risk for recurrence. The test can be used to quantify an individual patient’s 10-year risk of developing a recurrence (ie, ipsilateral breast event [IBE]). The score provides independent information on recurrence risk beyond clinical and pathological variables. We are not just reinventing the wheel here,” said Lawrence J. Solin, MD, chair of radiation oncology at Einstein Medical Center in Philadelphia, PA.
“The study is important because DCIS is a common diagnosis due to increased use of screening mammography, and it is not clear which patients will go on to recur. Many patients are treated with radiation. So far, we haven’t been able to identify clinical characteristics of patients with DCIS who can avoid it,” said Jennifer Ligibel, MD, assistant professor at Dana-Farber Cancer Institute in Boston, MA, who moderated a press conference where this study was discussed.
The validation study was based on tumor samples from 327 patients enrolled in ECOG 5194, a multi-institutional study of patients with low-, intermediate-, or high-grade DCIS who had been treated with breast conservation, had wide negative margins, and did not receive any radiation; tamoxifen was optional.
A subset of 12 genes from the Oncotype DX 21-gene assay was used to study the tumor samples. Patients were categorized as low-, intermediate-, or high-risk according to prespecified characteristics.
Three-quarters of patients were low risk, Solin said.
The DCIS score on the 12-gene assay was a highly significant and strong predictor of local recurrence (P = .02) and invasive local recurrence (P = .01) over a 10-year period.
Solin did not know what the cost of the 12-gene array would be once it is made available. “The cost of the study will be determined by Genomic Health. If we can use this test to spare patients from other adjuvant therapies, the test will be cost effective,” he stated.
Test results will be helpful in sparing low-risk patients from having unnecessary therapy and in selecting radiation (and tamoxifen) for high-risk patients, but treatment selection is not clear for intermediate-risk patients. “That group is always challenging, but at least this test allows us to provide patients information on their individual risk level. The numbers of patients in the intermediate-risk group is actually very small. Most patients with DCIS are low risk,” Solin said.