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TAILORx trial results – further clarity on the utility of the 21-gene assay in early breast cancer

The results of the TAILORx trial that were presented at the recent ASCO meeting and published in the NEJM in June will further assist in the clinical decision-making around adjuvant therapy in early breast cancer patients. (1)

The uncertainty about the best treatment approach for women with a mid-range score of 11 – 25 on the Oncotype DX® Breast Recurrence Score test has been looked at in this trial and, according to the published data, seems to put this to rest. The trial design addressed this question and ‘provides a very definitive answer,’ said the lead investigator, Dr Joseph A. Sparano.

This prospective phase III trial has shown that endocrine therapy (ET) alone was noninferior to ET plus chemotherapy for women with oestrogen receptor (ER)−positive, HER2-negative, axillary node negative, early-stage breast cancer with a midrange score measured by this gene expression assay. Almost two-thirds (almost 7000 patients) of the more than 10,000 patients enrolled in the study had a midrange recurrence score of 11 to 25.

According to the authors, the new findings suggest that chemotherapy may be avoided in about 70 percent of women with HR-positive, HER2-negative, node-negative breast cancer, that is:

  • older than 50 and with a recurrence score of 11 – 25 (45 percent)
  • any age with a recurrence score of 0 – 10 (16 percent)
  • 50 years old or younger with a recurrence score of 11 – 15 (8 percent)

The findings suggest that chemotherapy may be considered for the remaining 30 percent of women with HR-positive, HER2-negative, node-negative breast cancer:

  • any age with a recurrence score of 26 – 100 (17 percent)
  • 50 years old or younger with a recurrence score of 16 – 25 (14 percent)

These results demonstrate that chemotherapy is not beneficial for most women in the intermediate-risk group. This data adds to findings from the TAILORx analysis published in 2015 that provided prospective evidence that the test women with a low risk (0 – 10) of recurrence could be spared chemotherapy.

As always, there are caveats to these findings; the most important one being that, on subgroup analysis of premenopausal women and those younger than 50 years old at the higher end of the intermediate-risk range (16 – 25), the results did show a small benefit from adjuvant chemotherapy. This means that in this subgroup especially, the pros and cons of adjuvant chemotherapy need to be debated carefully.

The current ICON Clinical Protocols guidelines for the use of gene expression assay are:

Oncotype DX® to be considered only if ALL of the following criteria are met:

  1. Patient medically fit for, and willing to undergo chemotherapy
  2. Primary tumour 0.5 – 5cm. (T1, T2, T3)
  3. ER positive
  4. HER2 negative
  5. PN0 or PN1mic (<2mm nodal metastasis)

This trial result offers further support to improving the management of early breast cancer patients. The increased clinical utility of this test (the higher numbers of patients that could be spared adjuvant chemotherapy) will assist ICON in our ongoing efforts to encourage medical schemes to fund gene expression assay testing for those patients who fit this clinical criteria.

Reference:

  1. Sparano J.A., Gray R.J., et al. Adjuvant Chemotherapy Guided by a 21-Gene Expression Assay in Breast Cancer. NEJM. 2018 Jun; DOI: 10.1056/NEJMoa1804710
    https://www.nejm.org/doi/full/10.1056/NEJMoa1510764

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