SAN ANTONIO, TX—Premenopausal women with luminal A subtype breast cancer had comparable 10-year disease-free survival rates regardless of whether they received adjuvant chemotherapy, according to data presented at the 2015 San Antonio Breast Cancer Symposium.1

Intrinsic subtypes are proven prognostic in many settings and appear promising for predicting benefit of chemotherapy. The data in this trial is from the phase III Dutch Breast Cancer Cooperative Group 77B (DBCG77B) clinical trial. Using data from a completed trial that had saved tissue samples for future studies enabled the researchers to find answers to their hypothesis in less time.

In the DBCG77B trial, 1146 premenopausal women who had lymph node-positive invasive breast cancer larger than 5 cm were randomized to two chemotherapy and two no-chemotherapy arms. Women in the chemotherapy arms received either cyclophosphamide or a combination of cyclophosphamide, methotrexate, and fluorouracil (CMF).

The researchers analyzed the tissue samples that were available 709 patients and found 165 of them had had the luminal A subtype. They found no difference in 10-year invasive disease-free survival rates between women with luminal A disease who received chemotherapy and those who did not. The 468 patients with nonluminal A disease (luminal B, HER2E, and triple-negative subtypes) who received chemotherapy were 50% less likely to have their disease recur in 10 years, compared with women with nonluminal A disease who did not receive chemotherapy.

The researchers note that none of the women in this trial received hormone therapy as adjuvant treatment; therefore, the trial used in this study may not reflect the current standard of care. However, endocrine therapies are known to reduce tumor sensitivity to chemotherapy.

REFERENCE

1. Nielsen TO, Jensen MB, Gao D, et al. High risk premenopausal luminal A breast cancer patients derive no benefit from adjuvant chemotherapy: results from DBCG77B randomized trial. Oral presentation at: San Antonio Breast Cancer Symposium; December 9-12, 2015; San Antonio, TX.