Study Looks for Link Between Oncotype DX Test Use and Chemotherapy in Older Diagnosed Women

"Is the link real?"

The Oncotype DX test is a genomic test that analyzes the activity of a group of 21 genes that can affect how a cancer is likely to behave and respond to treatment. Doctors use the Oncotype DX test to help figure out a woman's risk of early-stage, estrogen-receptor-positive breast cancer coming back (recurrence), as well as how likely she is to benefit from chemotherapy after breast cancer surgery.

A second test, the Oncotype DX DCIS test, analyzes 12 genes and helps doctors figure out a woman's risk of DCIS coming back and/or the risk of a new invasive cancer developing in the same breast, as well as how likely she is to benefit from radiation therapy after DCIS surgery.

The Oncotype DX test results assign a Recurrence Score -- a number between 0 and 100 -- to the early-stage breast cancer. You and your doctor can use the following ranges to interpret your results for early-stage invasive cancer:

  • Recurrence Score lower than 18: The cancer has a low risk of recurrence. The benefit of chemotherapy is likely to be small and will not outweigh the risks of side effects.
  • Recurrence Score between 18 and 31: The cancer has an intermediate risk of recurrence. It's unclear whether the benefits of chemotherapy outweigh the risks of side effects.
  • Recurrence Score greater than 31: The cancer has a high risk of recurrence, and the benefits of chemotherapy are likely to be greater than the risks of side effects.
  • A study has found that older women diagnosed with early-stage, estrogen-receptor-positive disease who had the Oncotype DX test were no more or less likely to have chemotherapy after surgery than women who didn't have the test.

    The study was published online on Aug. 27, 2015 by the journal JAMA Oncology. Earlier studies have found that about 20% to 30% of doctors said they changed their recommendation about chemotherapy based on Oncotype DX test score results. But according to the researchers who did this study, none of the previous studies looked at how having the Oncotype DX test affected whether a woman would have chemotherapy in a real-world clinical setting. So they decided to investigate. To do the study, the researchers looked at information in the SEER database on women covered by Medicare who were diagnosed with early-stage, estrogen-receptor-positive breast cancer and had the Oncotype DX test between 2005 and 2009. SEER databases are large registries of cancer cases from sources throughout the United States maintained by the National Institutes of Health. Women covered by Medicare must be 65 or older, so all the women in the study were 65 or older.

    If you've been diagnosed with early-stage, estrogen-receptor-positive breast cancer and are weighing the pros and cons of adding chemotherapy to your treatment plan, the Oncotype DX test may help you and your doctor make that decision. Besides any genomic test results, you and your doctor will consider other factors when developing your treatment plan, including:

  • your age
  • the size of the cancer
  • hormone-receptor protein levels
  • the grade of the cancer
  • any other health conditions you have
  • your personal preferences
  • Together, you can make the best treatment decisions for YOU!

    SOURCE: Journal JAMA Oncology, August 27, 2015. Synopsis by breastcancer.org.