MammaPrint Test Reduces Use of Adjuvant Chemo Among Patients With Early-stage Breast Cancer

The MammaPrint genetic test can reduce the use of adjuvant chemotherapy following surgery among patients with early-stage breast cancer who are considered at high risk for disease recurrence, a study presented American Academy for Cancer Research (AACR) Annual Meeting 2016 has shown.¹

For the prospective, international, controlled, phase 3 MINDACT trial, researchers sought to evaluate the clinical utility of the 70-gene signature MammaPrint genetic test combined with common clinical-pathological criteria for selecting patients with breast cancer and 0 to 3 positive nodes for adjuvant chemotherapy.

Researchers enrolled 6693 women who had undergone surgery for early-stage breast cancer. All participants were classified as having low or high risk for cancer recurrence by both the MammaPrint genetic test and Adjuvant! Online, a tool that calculates risk of tumor recurrence based on common clinical and pathological criteria.

Patients were then divided into 4 groups:  2745 were considered having low risk of recurrence by both risk-assessment methods (G-low/C-low), 1806 were classified as having high risk by both methods (G-high/C-high), 592 were categorized as having high risk by MammaPrint and low risk by Adjuvant! Online (G-high/C-low), and 1550 were categorized as having low risk by MammaPrint and high risk by Adjuvant! Online (G-low/C-high).

Patients classified as G-low/C-low were assigned to no adjuvant chemotherapy. Participants categorized as G-high/C-high were assigned to adjuvant chemotherapy. Patients categorized as G-high/C-low or G-low/C-high were randomly assigned to receive either adjuvant chemotherapy or no adjuvant chemotherapy.

Results showed that among the 3356 C-high patients, treatment according to MammaPrint reduced the receipt of chemotherapy by 46%, with a 5-year metastasis-free survival of 94% among G-low/C-high patients whether they received adjuvant chemotherapy or not. The study demonstrated that 14% of patients could avoid chemotherapy by using the 70-gene signature assay to assess risk as compared with the conventional approach.

“At present, most oncologists make recommendations for adjuvant chemotherapy after considering common clinical and biological criteria such as patient’s age, and the stage and grade, as well as the hormonal receptor and HER2 status of his or her tumor,” said lead author Martine Piccart, MD, PhD, head of the Medicine Department at the Jules Bordet Institute in Brussels, Belgium, and co-founder and chair of the Breast International Group (BIG).

“The MINDACT trial results provide level 1A evidence that using MammaPrint could change clinical practice by substantially de-escalating the use of adjuvant chemotherapy and sparing many patients an aggressive treatment they will not benefit from.”

Reference

1. Piccart M, Rutgers E, van ‘t Veer LJ, et al. Primary analysis of the EORTC 10041/ BIG 3-04 MINDACT study: A prospective, randomized study evaluating the clinical utility of the 70-gene signature (MammaPrint) combined with common clinical-pathological criteria for selection of patients for adjuvant chemotherapy in breast cancer with 0 to 3 positive nodes. Oral presentation at: AACR Annual Meeting 2016; April 16-20, 2016; New Orleans, LA.