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2019 ASCO: New TAILORx Data Provide Treatment Guidance for Women Under 50 With Early Breast Cancer

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Key Points

  • There was no benefit from chemotherapy for younger women (age 50 or less) with a recurrence score of 16–20 and at low risk clinically.
  • Integration of recurrence score and clinical risk found a benefit for women aged 46–50 years who were premenopausal but not postmenopausal, and a trend toward chemotherapy in women aged 41–45 years, but no benefit in women aged 40 years or under who are less likely to develop premature menopause from chemotherapy.

New information about adjuvant therapy to prevent recurrence of breast cancer in women 50 years of age or younger has emerged from the Trial Assigning Individualized Options for Treatment (Rx), or TAILORx.

An analysis of a prespecified secondary endpoint in this trial found that an assessment of a woman’s recurrence risk based on classic clinical features—tumor size and histologic grade—adds prognostic information that is complementary to the 21-gene recurrence score test. Integration of the recurrence score with clinical risk may help identify more young women who may be spared chemotherapy than originally reported, and it may also help identify young women who stand to benefit from more effective antiestrogen therapy. The analysis was published by Sparano et al in The New England Journal of Medicine and presented at the 2019 ASCO Annual Meeting (Abstract 503).

Previous TAILORx Findings

The new findings complement the original, definitive TAILORx conclusion reported at last year’s ASCO Annual Meeting: that 70% of women with hormone receptor (HR)-positive, HER2-negative, axillary lymph node–negative breast cancer can forego chemotherapy when guided by recurrence score.

“Last year’s TAILORx results gave clinicians high-quality data to inform personalized treatment recommendations for women,” said lead author Joseph A. Sparano, MD, Associate Director for Clinical Research at the Albert Einstein Cancer Center and Montefiore Health System and Vice Chair of the ECOG-ACRIN Cancer Research Group. “With this new analysis, it is clear that women ages 50 or younger with a recurrence score result between 16 and 20 and at low risk, clinically, do not need chemotherapy. Furthermore, the integration of the recurrence score with clinical risk information could identify premenopausal women with higher clinical risk who may benefit from ovarian function suppression and more aggressive antiestrogen therapy.”

Secondary Analysis

The objective of the prespecified secondary analysis was to evaluate whether clinical risk provides additional prognostic or predictive information to the recurrence score results. Of 9,427 women in TAILORx with a recurrence score and clinical risk information, 70% were determined to be low clinical risk (tumor ≤ 3 cm and low-grade, ≤ 2 cm and intermediate-grade, or ≤ 1 cm and high-grade) and 30% were identified as high clinical risk (not meeting low clinical risk criteria). While clinical risk provided additional prognostic information across all recurrence score groups, disease-free survival and distant recurrence–free interval rates were similar with and without chemotherapy in the entire recurrence score 11–25 group, irrespective of clinical risk.

For the overall population, clinical risk alone was not predictive of chemotherapy benefit. This was also true for the two-thirds of women who were over the age of 50, and for the remaining women aged 50 or younger, there was a trend favoring chemotherapy, irrespective of clinical risk, though this was not significant.

Researchers studied the association between age at diagnosis and chemotherapy benefit in the group of younger women (age 50 or less) in TAILORx with a recurrence score of 16–25. This group was of particular interest because they were part (14%) of the 30% of women in the original TAILORx findings for whom it was suggested that chemotherapy may be considered. Researchers sought to determine whether integration of recurrence score and clinical information would help define this group. They found there was no benefit from chemotherapy for younger women (age 50 or less) with a recurrence score of 16–20 and at low risk clinically.

Researchers then explored the association between age at diagnosis and chemotherapy benefit in this group same to determine if integration of recurrence score and clinical risk could help identify premenopausal women who might stand to benefit from more effective antiestrogen therapy. In the original TAILORx report, researchers noted that it was unclear if the modest chemotherapy benefit seen in this group was due to a cytotoxic effect in eradicating micrometastatic disease, a castration effect in inducing early menopause, or both. Integration of recurrence score and clinical risk found a benefit for women aged 46–50 years who were premenopausal but not postmenopausal, and a trend toward chemotherapy in women aged 41–45 years, but no benefit in women aged 40 years or under who are less likely to develop premature menopause from chemotherapy. In addition, there was no consistent effect favoring chemotherapy in older women. Taken together, these findings suggest that the chemotherapy benefit observed for the recurrence score 16–25 group may be due to a castration effect associated with cytotoxic therapy.

The authors concluded, “Clinical risk stratification provides additional prognostic information to the 21-gene recurrence score, but not prediction of chemotherapy benefit in the overall TAILORx population or those > 50 years, and facilitates more refined estimates of absolute chemotherapy benefit for women ≤ 50 years with a recurrence score [of] 16–25.”

Disclosure: For full disclosures of the study authors, visit coi.ascopubs.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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