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Predicting which women have breast cancers that will respond to hormone therapy alone


This research is relevant for:

Checked Breast cancer survivors

Checked Women under 45

Checked Women over 45

Unhecked Men with breast cancer

Unhecked Metastatic breast cancer

Unhecked Triple negative breast cancer

Unhecked Previvors

Unhecked BRCA mutation carriers

Checked ER/PR +

Unhecked Her2+ breast cancer

Checked Special populations: Patients who have used the Oncotype DX test or are thinking about using the Oncotype DX test

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Not all breast cancer is the same. Nor do all cancers react similarly to chemotherapy, but a specific test helps doctors and patients decide if an early cancer needs to be treated with chemotherapy. This week we review a recent paper that showed the Oncotype DX test reliably identifies women with ER+ early-stage breast cancer who can be treated with hormone therapy alone.


STUDY AT A GLANCE

This study is about:

Whether a low score on the Oncotype DX Recurrence Score test, a test that identifies the level of gene activity in breast tumors, can show which breast cancer patients are candidates for hormone therapy alone, without chemotherapy.

Why is this study important? 

It can help some people avoid unnecessary chemotherapy.

Study findings: 

After 5 years of taking hormone therapy without chemotherapy, women whose tumors had low Oncotype DX test scores had a very low recurrence rate.

What does this mean for me?

If a low Oncotype DX test score is a valid reflection for the risk of cancer recurrence, women whose tumors reflect this low score can feel comfortable receiving hormone therapy only.  This study shows that a low score (0-10) on the Oncotype DX test can accurate predict which women will not need chemotherapy in addition to their hormone therapy for their cancers.

Questions to Ask Your Health Care Provider:

  • How does the Oncotype DX test work?
  • Why does a low score mean I don’t need chemotherapy?
  • How long should I stay on hormone therapy?
  • My Oncotype DX test score was low—should I feel comfortable receiving hormone therapy only?
  • I inherited a BRCA mutation; should I still consider this type of testing?
  • I am worried about recurrence—can I still get chemotherapy? 

IN DEPTH REVIEW OF RESEARCH

Study background:

In 2014, more than 100,000 women in the U.S. were diagnosed with estrogen receptor-positive (ER+) breast cancer that had not spread to the lymph nodes.  ER-positive breast cancer can be treated with “hormone therapy” drugs (such as tamoxifen or aromatase inhibitors) that restrict tumor growth, either by blocking the effects of estrogen on tumor cells or by stopping estrogen production in the body.  Previous research showed that 5 years of tamoxifen therapy reduces the 15-year risk of cancer recurrence and death.  The patients from those studies did not receive chemotherapy, showing that hormone therapy alone was effective. Women with ER+ breast cancer who receive both hormone therapy and chemotherapy might be overtreated, because hormone therapy alone would likely have been enough for most of them. To prevent unnecessary chemotherapy, both patients and health care providers need to know who can be safely treated with hormone therapy alone.

The Oncotype DX breast cancer test looks at breast tumor samples to measure activity (sometimes called expression) in 21 different genes—the level of activity in these 21 genes has been shown to correlate with the risk that the breast cancer will recur.  Test results are given as a recurrence score between 0-100. The idea behind the test is: the lower the recurrence score, the less likely the cancer will return, and the less likely that the patient will benefit from receiving chemotherapy in addition to hormone therapy. This study is the first to follow a patient population from the time of diagnosis, an important step in proving the usefulness of the test. Most previous studies used archived tumor samples, and did not follow a study population during a set period or monitor their outcomes. 

The hormone therapies used by the patients in this study were aromatase inhibitors, tamoxifen, tamoxifen followed by aromatase-inhibition therapy, or ovarian-function suppression. 3% of patients used an unknown therapy. 

Researchers of this study wanted to know:

Whether the Oncotype DX test can be used to identify patients who will benefit from hormone therapy alone (no chemotherapy).

Population(s) looked at in the study:

1,626 women who:

  • had a low recurrence score (0-10)
  • were ER receptor-positive
  • were HER2-negative
  • had cancer that had not spread to the lymph nodes
  • met established guidelines for receiving chemotherapy

Study finding(s): 

  1. About 16% of the eligible population had a score between 0-10.
  2. Of the 1,626 women who had a score between 0-10, 88 invasive cancers and deaths were reported.
  3. At 5 years, for women with a 0-10 score who only received hormone therapy:
  • the rate of overall survival was 98%
  • 93% did not have a cancer recurrence at a distant site

Limitations:

In patients with ER+ positive, HER2-negative breast cancer, late recurrence (after 5 years) accounts for about half of distant recurrences. This study followed women for only 5 years. So while the results of this study are favorable for using Oncotype DX to predict 5-year recurrence, just how these women will fare after 5 years remains unknown.  This study also did not consider whether or not the woman had a mutation in BRCA or other gene associated with increased cancer risk, so it is unclear whether the results can be applied to hereditary breast cancer.  The study also did not include men with breast cancer.

Conclusions:

A low score (0-10) on the Oncotype DX test can accurately predict which breast cancer patients will respond well to hormone therapy alone and can avoid chemotherapy. Patients with low scores can feel comfortable knowing that chemotherapy is not absolutely necessary for their treatment plan. However, the majority of the 10,253 patients who took the Oncotype DX test, about 67% had a mid-range tumor score of 11-25. It is unknown whether women who have tumors with this type of midrange score will respond well to hormone therapy without chemotherapy. More study on this is needed, as women who scored in this mid-range comprised most of the population of women with ER-positive, HER-2 negative, axillary node-negative breast cancers.

It is important to note that the Oncotype DX test identifies which genes are active in the breast tumor.  This type of tumor testing for gene activity or expression is different than genetic testing for inherited cancer risk.  Women with breast cancer before age 50, triple-negative breast cancer, a strong family history of breast cancer and/or ovarian cancer, and men with breast cancer should discuss genetic counseling and/or testing with their health care provider.   

References:

Sparano JA, Gray DF, Makower KI, et al. “Prospective Validation of a 21-Gene Expression Assay in Breast Cancer.” The New England Journal of Medicine. Initially published online September 28, 2015.  

Posted 10/20/15

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