Posted on June 18th, 2013 by
The Oncotype DX® DCIS Score predicts the 10-year risk of local recurrence, defined as recurrence of DCIS or invasive breast cancer in the same breast, and can help guide radiation treatment decision-making for women with DCIS who are treated with breast-conserving surgery, according to the results of a study published in the Journal of the National Cancer Institute.
Ductal carcinoma in situ refers to a condition in which abnormal cells are found within a breast duct but have not spread outside of the duct to other tissues in the breast. It is most commonly detected by screening mammography. If not treated, some cases of DCIS may progress to invasive breast cancer. More than 50,000 patients are diagnosed with DCIS each year.
Treatment for DCIS may involve breast-conserving surgery (lumpectomy) or mastectomy. For DCIS patients who choose breast-conserving surgery, additional treatment with radiation therapy has been shown to reduce the risk of recurrence, but may not be necessary for all women. If the characteristics of the DCIS suggest that it is unlikely to recur, surgery alone (without radiation therapy) may be an option.
The Oncotype DX breast cancer test was originally developed to provide information about recurrence risk and need for chemotherapy to certain groups of women with early-stage, invasive breast cancer. To determine whether the test can also predict recurrence risk in women with DCIS, researchers developed a DCIS Score that can be generated by the test. To evaluate whether the DCIS Score could predict recurrence risk, researchers analyzed 327 DCIS tumor samples from women with DCIS who had participated in an earlier clinical trial of DCIS treatment. The women had been treated with breast-conserving surgery but had not received radiation therapy.
The study validated that the Oncotype DX DCIS Score predicted 10-year local recurrence (DCIS or invasive carcinoma) based on a patient’s individualized underlying tumor biology, regardless of whether adjuvant tamoxifen was given. Based on the DCIS Score, women were classified as low, intermediate, or high risk. The results indicated that 70 percent of patients had a low DCIS Score and may be able to forego radiation therapy. Compared with patients whose tumor had an intermediate or high DCIS Score, patients with a low DCIS Score had a significantly lower likelihood of a local recurrence at 10 years (about 11 percent vs. 26 percent, respectively). The table below shows specifics:
Table 1: DCIS Score and Risk of DCIS Recurrence or Invasive Carcinoma
|Low Risk||Intermediate Risk||High Risk|
|10-year risk of developing local recurrence of DCIS||
|10-year risk of developing invasive carcinoma||
The researchers found that the DCIS Score was predictive of local recurrence across patient subgroups regardless of lesion size, grade, surgical margins, or menopausal status. They concluded that the DCIS Score quantifies the risk of local DCIS recurrence and invasive carcinoma. They note that the Oncotype DX DCIS Score provides a new tool that will help physicians and patients make more informed treatment decisions.
Solin LJ, Gray R, Baehner FL, et al. A multigene expression assay to predict local recurrence risk for ductal carcinoma in situ of the breast. Journal of the National Cancer Institute. 2013; 105(10): 701-710.
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