A multigene test called Oncotype DX DCIS Score (DCIS Score) was validated as a predictor of risk of disease recurrence among women treated with breast-conserving surgery alone for ductal carcinoma in situ (DCIS), a noninvasive breast abnormality, according to data from a large, population-based study presented at the 2014 San Antonio Breast Cancer Symposium.

The test could provide important individualised information on the risk of recurrence after treatment by breast-conserving surgery, which can help better inform physicians and patients on their future risks and the need for additional treatment.

“We found that the DCIS Score was a good predictor of whether a patient with DCIS who was treated with breast-conserving surgery alone would experience recurrence of DCIS or invasive breast cancer in the same breast,” said Eileen Rakovitch, MD, an associate professor and radiation oncologist at Sunnybrook Health Sciences Centre and scientist at Sunnybrook Research Institute in Toronto, Ontario. “These data confirm the results of a study reported last year but in a more diverse population.

“Currently, most patients diagnosed with DCIS undergo breast-conserving surgery,” continued Rakovitch, who is also an adjunct scientist in the Institute for Clinical Evaluative Sciences at the University of Toronto. “Decisions about further treatment, such as radiation therapy, are made based on clinical information like age at diagnosis and size and grade of the tumour. The DCIS Score can provide additional information on an individual’s risk of recurrence to help patients and their physicians make the personal decision about whether or not to undergo additional treatment.”

After a median follow-up of 9.4 years, among 571 patients with DCIS who were treated with breast-conserving surgery alone and had negative margins after surgery, those who were classified as having a low-risk DCIS Score had a significantly lower risk of developing a recurrence compared to individuals who had an intermediate or high-risk DCIS score.

Every 50 point increase in the DCIS Score was associated with a two-fold increase in the risk of developing recurrence.

Rakovitch and colleagues identified 3335 women diagnosed with DCIS from 1994 to 2003 in their study to test DCIS Score as a predictor of recurrence risk.

Tumour samples were collected for 1569 patients, 718 of whom were treated with breast-conserving surgery only and 846 who were treated with breast-conserving surgery followed by radiation therapy.

Among the patients treated with breast-conserving surgery only, 571 had negative margins, and 100 of these patients had disease recur in the same breast. Forty-four had DCIS at recurrence and 56 had invasive breast cancer; one patient had both DCIS and invasive breast cancer.

“We are working on completing the analysis of the ability of DCIS Score to predict recurrence risk for those patients with DCIS who were treated with breast-conserving surgery followed by radiation therapy,” said Rakovitch.

“We are also interested in developing a nomogram that will integrate DCIS Score with clinical features to further help inform patients and physicians as they decide on the patient’s optimal treatment course.”

The researchers followed the REMARK guidelines for the reporting of tumour marker prognostic studies.

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Source: SABCS