Trial Results: The TAILORx trial continues to provide reassurance that many women with early breast cancer can safely forego chemotherapy

About one-half of all new breast cancers in the United States each year are estrogen receptor-positive (ER+) and HER2-negative (HER2-) without any spread to the nearby lymph nodes. Therefore, recurrence is a primary concern for women with this type of breast cancer.

The landmark TAILORx trial followed 10,273 women with this type of breast cancer for at least 5 years (median of 7.5 years). Trial participants with a score of 11-25 on the Oncotype DX Breast Recurrence Score (R) test were considered at moderate risk for recurrence.* To lower their risk, they were randomized to take a standard five-year course of endocrine therapy, either with or without 4-6 weeks of chemotherapy. In 2018, TAILORx found no difference in outcomes between the two groups.

TAILORx established that women at medium risk for recurrence could safely take endocrine therapy alone. It is one of the first large-scale trials to examine a method for personalizing cancer treatment.

"The results of TAILORx have allowed many women to avoid the unnecessary side effects of chemotherapy," says Joseph A. Sparano, MD, deputy director of The Tisch Cancer Center at Mount Sinai Health System in New York. Dr. Sparano is leading the TAILORx trial for the ECOG-ACRIN Cancer Research Group.

Now, 12 years of survival and recurrence outcomes are available from TAILORx.

"The immediate clinical impact is that with longer follow-up, the main TAILORx study findings remain unchanged. Therefore, physicians can continue to use the 21-gene recurrence score results to guide decisions about the use of chemotherapy," says Dr. Sparano.  

As in the original analysis, the subgroup of women aged 50 and younger with a score of 21-25 or 16-25 and having clinical features of high risk derived some chemotherapy benefit that persists out to 12 years. This cohort accounted for 7% of the trial population.

One reason for this updated analysis is at least 50% of recurrences happen more than 5 years after diagnosis. Among the new information:

• For women with a score of 0-25 treated with endocrine therapy alone, recurrence rates were very low on average, at less than 1% per year over the 12 years. However, more late recurrences occurred beyond 5 years after diagnosis than in the first 5 years. "Women need to stay vigilant with cancer screening after a breast cancer diagnosis," says Dr. Sparano.
• The cancer recurrence rates remained high for women with a score of 26-100, despite adding chemotherapy. Dr. Sparano says that more effective treatments are needed for women with a very high recurrence score who have an unacceptably high recurrence risk despite the use of chemotherapy.
• Black women in the trial were at higher risk of recurrence in the first 5 years after diagnosis but not later. "We observed racial disparities that could not be explained by inequities in social determinants of health or by stopping anti-hormonal endocrine therapy early," says Dr. Sparano. "More research is needed to understand what is driving these disparities."

This study provides doctors with new data to make personalized treatment recommendations for women.

"The TAILORx findings will give women with early-stage breast cancer greater certainty that anti-estrogen therapy will decrease their risk of recurrence and increase their chance for survival, whereas chemotherapy will not," said Mary Lou Smith, J.D., MBA, president of the Research Advocacy Network, who helped design the study as chair of the ECOG-ACRIN Cancer Research Advocates Committee.

* This commercial test predicts how likely breast cancer is to come back after surgery and the possible benefit of having chemotherapy. The test gives a score between 0 and 100, and people who score above a certain number are more likely to be offered chemotherapy.

Related Post: Come again? Communicating clearly about risk of recurrence after early-stage breast cancer