A DCIS Score generated by the Oncotype DX breast cancer test provides information about how likely it is that breast ductal carcinoma in situ (DCIS) will recur. This may help guide decisions about whether women with DCIS need radiation therapy after breast-conserving surgery. These results were presented at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium.
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.
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. The test has been added to US medical guidelines for this purpose.
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. The ability of the DCIS Score to predict recurrence risk was evaluated among 327 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.
- Three-quarters of the patients had a low risk of recurrence based on the DCIS Score. These patients may not need radiation therapy after breast-conserving surgery.
- Among women with a low risk of recurrence based on the DCIS Score, the likelihood of any kind of local recurrence (a recurrence that was either DCIS or invasive breast cancer) was 12 percent. The likelihood of a recurrence that involved invasive breast cancer 5 percent.
- Among women with a high risk of recurrence based on the DCIS Score, the likelihood of any kind of local recurrence was 27 percent. The likelihood of a recurrence that involved invasive breast cancer was 19 percent.
These results suggest that the Oncotype DX DCIS Score provides information about the risk of recurrence among women with DCIS. This information may help guide decisions about whether radiation therapy is necessary.
Reference: Solin LJ, Gray R, Baehner FL. A Quantitative Multigene RT-PCR Assay for Predicting Recurrence Risk after Surgical Excision Alone without Irradiation for Ductal Carcinoma In Situ (DCIS): A Prospective Validation Study of the DCIS Score from ECOG E5194. Presented at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium. December 6-10, 2011. Abstract S4-6.
Posted December 13, 2011