Using a Gene Test to Assess Recurrence Risk for Women with Ductal Carcinoma In Situ
December 28, 2014
Participants at the San Antonio Breast Cancer Conference were recently updated on the status of OncotypeDx for Ductal Carcinoma In Situ (DCIS).
Providers at the Swedish Cancer Institute have been using this technology since it became available about 4 years ago. The test is done on the tissue after surgery to see if it might be safe to not add radiation therapy to lumpectomy / partial mastectomy for carefully selected DCIS patients.
There is now data on patients that have been followed for 10 years with a finding that low-score patients have an acceptably low risk of developing more DCIS in that breast if they do not have the radiation treatment. The intermediate and high risk score groups had significantly higher recurrence rates. About half of women treated for DCIS who have a recurrence will have an invasive cancer at the time of recurrence.
The test provides patients and providers with a “recurrence score” and can help to weigh the risks and benefits of radiation after lumpectomy. It is important to make sure it is safe to eliminate the radiation therapy – which has been shown to decrease the recurrence risk for all women. Typically a woman can only have a single course of radiation to the treated breast and if cancer comes back in the same breast, mastectomy is advised.
It is crucial to note that this testing can only be done after surgery has been performed and adequate margins (> 3mm) are obtained. Those women with large amounts of DCIS (over 2.5 cm) or those that have more than one site of disease are not eligible. This test does not eliminate the role of surgery but can help some, appropriately selected women with DCIS safely avoid radiation therapy. Ultimately, this is another tool to help providers tailor treatment in a meaningful way, but is not applicable to all women with DCIS.