Oncotype DX Test Can Help Decide if Radiation Needed After DCIS Surgery

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A study found that Oncotype DX, a genomic test, can help doctors decide if women diagnosed with DCIS (ductal carcinoma in situ) need radiation therapy.

The results were presented at the 2011 San Antonio Breast Cancer Symposium.

DCIS is the most common form of non-invasive breast cancer. DCIS usually is treated by surgically removing the cancer -- lumpectomy in most cases. After surgery, hormonal therapy medicine may be recommended if the DCIS is hormone-receptor-positive (most are). Radiation therapy also is recommended for many women.

Routine radiation therapy after DCIS surgery was common in the past, but newer DCIS treatment guidelines say that radiation therapy after surgery doesn't have to be given routinely to all women. At the same time, doctors aren't always sure which women will benefit from radiation therapy, so a test to help guide the decision would be helpful.

A genomic test (also called a genomic assay) analyzes the activity of a group of genes that can affect how a cancer is likely to behave and respond to treatment. The test is performed on a sample of breast cancer tissue. Several genomic tests, including Oncotype DX, are being used by doctors to help figure out a woman's risk of early-stage, hormone-receptor-positive breast cancer coming back (recurrence) as well as how likely she is to benefit from chemotherapy. The genomic test results are a score that relates to recurrence risk. The higher the score, the greater the risk of recurrence and the more likely it is that a woman would benefit from chemotherapy.

This study looked at whether using the Oncotype DX test could help women diagnosed with non-invasive DCIS and their doctors make more informed treatment decisions. The researchers wanted to see if the Oncotype DX test did a good job of estimating the recurrence risk of DCIS and/or the risk of a new, invasive breast cancer developing in the same breast where the DCIS was. Using the Oncotype DX test this way might help doctors decide if the benefits of including radiation therapy in a woman's DCIS treatment plan outweigh the risks and inconvenience.

The Oncotype DX test was done on 327 DCIS tissue samples from women in another study looking at managing DCIS without radiation therapy after surgery. Each test resulted in a DCIS score that predicted recurrence risk. Recurrence included both another diagnosis of DCIS in the same breast OR a diagnosis of invasive cancer in that breast.

The researchers compared the Oncotype DX DCIS scores with the women's outcomes. Half the women were followed for 9 or more years. The other half were followed for shorter periods of time. Twenty women had a DCIS recurrence in the same breast and another 26 were diagnosed with invasive cancer in the same breast.

The study found that the DCIS score did help predict recurrence.

Women with low DCIS scores were unlikely to have a recurrence. Only 12% of these women had a DCIS recurrence or were diagnosed with invasive breast cancer during follow-up and most of these recurrences were DCIS, not invasive cancer.

Women with high DCIS scores were more than twice as likely to have a recurrence than women with low DCIS scores; 27% of women with a high DCIS score had a DCIS recurrence or were diagnosed with invasive breast cancer during follow-up. Almost half of these recurrences were invasive cancer.

The results suggest that the Oncotype DX test does a good job of helping doctors estimate recurrence risk in women diagnosed with DCIS. The results could help doctors better judge which women diagnosed with DCIS are at high risk for recurrence or an invasive breast cancer diagnosis in the future and would benefit from radiation therapy after surgery. Based on the results, Genomic Health, the company that developed the Oncotype DX test, plans to make the score for DCIS available to doctors later this month.

If you've been diagnosed with DCIS, your doctor will recommend a treatment plan after surgery tailored to your specific recurrence risk for DCIS or invasive breast cancer. Your treatment plan may include radiation therapy, hormonal therapy, both, or neither. If you're deciding on treatments after DCIS surgery you might want to ask if the Oncotype DX test might help figure out if you would benefit from radiation therapy. Armed with the best information possible, you and your doctor can decide on a treatment plan that makes the most sense for your unique situation.

The Breastcancer.org DCIS pages contain more information on DCIS symptoms, diagnosis, and treatment.

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