Oncotype DX May Help Make Treatment Decisions for Breast Cancer That’s Metastatic at Diagnosis

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The Oncotype DX test is a genomic test that analyzes the activity of a group of 21 genes from a breast cancer tissue sample 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, HER2-negative breast cancer coming back (recurrence), as well as how likely she is to benefit from chemotherapy after breast cancer surgery.

The Oncotype DX test results assign a Recurrence Score -- a number between 0 and 100 -- to the early-stage breast cancer. Doctors use the following ranges to interpret the 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 of 18 up to and including 30: 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 or equal to 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.

Because the Oncotype DX test has been validated by much research, right now it is the most widely used genomic test. So doctors wondered if the Oncotype DX test could help make treatment decisions for breast cancer that is metastatic when first diagnosed. Doctors call this type of cancer “de novo stage IV” cancer.

A study suggests that the Oncotype DX test can offer relevant information about cancer progression and 2-year survival rates for women diagnosed with de novo stage IV cancer.

The research was published online on March 21, 2016 by the Journal of Clinical Oncology. Read the abstract of “Prognostic Impact of 21-Gene Recurrence Score in Patients With Stage IV Breast Cancer: TBCRC 013.”

To do the study, the researchers did Oncotype DX testing on tumor samples from 109 women who had been diagnosed with de novo stage IV breast cancer:

  • the women were 21 to 79 years old
  • primary tumor size ranged from 0.7 cm to 15 cm
  • 84% of the cancers were estrogen-receptor-positive
  • 72% of the cancers were HER2-negative
  • 86% of the cancers were invasive ductal disease
  • 46% of the women had metastatic lesions only in their bones

The Oncotype DX testing successfully calculated Recurrence Scores for 101 women:

  • 22 women (20%) had a low-risk Recurrence Score; all these women were diagnosed with estrogen-receptor-positive, HER2-negative disease
  • 29 women (34%) had an intermediate-risk Recurrence Score; 26 of these women had estrogen-receptor-positive, HER2-negative disease and three had estrogen-receptor-positive, HER2-positive disease
  • 50 women (46%) had a high-risk Recurrence Score; 21 of these women had estrogen-receptor-positive, HER2-negative disease; 13 had estrogen-receptor-positive, HER2-positive disease; 10 had estrogen-receptor-negative, HER2-positive disease; and six had triple-negative disease

After about 2.5 years of follow-up:

  • the time until the cancer grew ranged from 16 months to 26 months
  • median survival time was 49 months; this means that half the women lived for longer than 49 months and half the women lived for shorter amounts of time

Overall, women with low- and intermediate-risk Recurrence Scores had better 2-year survival and a longer time until the cancer grew compared to women with high-risk Recurrence Scores.

This association between better survival and a longer time until the cancer grew and low- and intermediate-risk Recurrence Scores was especially notable for women diagnosed with estrogen-receptor-positive, HER2-negative disease:

  • Women in this group with low-risk Recurrence Scores had no cancer growth during the study.
  • All the women in this group with low-risk or intermediate-risk Recurrence Scores were alive during the study.

Because of the association between Recurrence Score and survival and time to cancer growth in women diagnosed with de novo stage IV disease that was estrogen-receptor-positive, HER2-negative, the researchers wondered if the Recurrence Score might help doctors predict this type of cancer’s response to treatment.

So the researchers looked at the first treatment the 69 women diagnosed with this type of cancer had received:

  • 49 women (71%) were first treated with hormonal therapy; 19 of these women had a low-risk Recurrence Score, 16 had an intermediate-risk Recurrence Score, and 14 had a high-risk Recurrence Score
  • 20 women (29%) were first treated with chemotherapy; three of these women had a low-risk Recurrence Score, 10 had an intermediate-risk Recurrence Score, and seven had a high-risk Recurrence Score

The researchers found that both the time until the cancer grew and 2-year survival time were shorter among this group of women with high-risk Recurrence Scores who were first treated with hormonal therapy compared to women with high-risk Recurrence Scores first treated with chemotherapy. The researchers said this might suggest that a high-risk Recurrence Score in women diagnosed with estrogen-receptor-positive, HER2-negative de novo stage IV disease might indicate that the cancer is resistant to hormonal therapy. So the Recurrence Score may be a good tool to help doctors select the women diagnosed with this type of breast cancer who would benefit from chemotherapy as a first treatment.

While these the results of this study are promising, more research needs to be done before doctors understand exactly how the Oncotype DX test may help make treatment decisions for women diagnosed with estrogen-receptor-positive, HER2-negative de novo stage IV breast cancer.

Stay tuned to Breastcancer.org for the latest news on tests to help make treatment decisions for all stages of breast cancer.



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