Guideline: Can MammaPrint guide treatment decisions?

IN-DEPTH REVIEW OF RESEARCH

Study background:

From 2001 to 2007 researchers organized a large randomized trial in Europe to see whether a commercial genomic tumor test called MammaPrint could reduce overtreatment with chemotherapy in patients with early-stage invasive breast cancer. More than 6,600 women participated at 112 institutions in 9 nations. Each participant’s clinical risk of cancer recurrence was determined using a web-based tool called Adjuvant! Online. Patient’s tumors were also tested using MammaPrint, which produced a genomic score. Participants with discordant clinical and genomic risk (either high clinical risk and low genomic risk or low clinical risk and high genomic risk) were randomly assigned to receive adjuvant chemotherapy or not. The results, which were published in the New England Journal of Medicine in August 2016, suggest that approximately 46% of women with breast cancer who are at high clinical risk for recurrence might not benefit from adjuvant chemotherapy. As a result, ASCO updated guidelines on the use of MammaPrint to guide decisions on the use of adjuvant chemotherapy in an ASCO Special Article published in the Journal of Clinical Oncology in August, 2017.

Researchers of this study wanted to know:

Can MammaPrint, a commercially available genomic test, help to reduce overtreatment in patients with early-stage breast cancer?

Population(s) looked at in the study:

MINDACT was a randomized trial that looked at 6,693 women with operable invasive breast cancer, 0 to 3 positive lymph nodes, and no distant metastases. Eligible patients were women between the ages of 18 and 70. Initially, only patients with node-negative disease were enrolled; however, the study was later amended in 2009 to include women with 1 to 3 positive nodes. Researchers determined participants’ clinical risk (using a modified version of Adjuvant! Online), genomic risk (using MammaPrint) and tumor samples.

The patients were divided into 4 main groups according to their clinical and genomic risk, and received either adjuvant chemotherapy or no therapy:

• Low clinical risk and low genomic risk: 2,745 patients (41.0%)
  • No adjuvant therapy
• Low clinical risk and high genomic risk: 592 patients (8.8%)
  • Randomized to chemotherapy or no chemotherapy
• High clinical risk and low genomic risk: 1,550 patients (23.2%)
  • Randomized to chemotherapy or no chemotherapy
• High clinical risk and high genomic risk: 1,806 patients (27.0%)
  • Adjuvant chemotherapy

Study findings: 

Among women with early-stage breast cancer who were at high clinical risk and low genomic risk for recurrence and did not receive chemotherapy, the 5-year survival rate was 94.7%; the survival rate for those who did receive chemotherapy was 96.2%. This difference of 1.5 percentage points suggests that approximately 46% of women with early-stage invasive breast cancer who are at high clinical risk and low genomic risk do not receive benefit from adjuvant chemotherapy. 

Conclusions:

ASCO used the results of the MINDACT trial to revise its clinical guidelines regarding the use of MammaPrint for decision making regarding use of adjuvant chemotherapy for patients with early-stage invasive breast cancer. MammaPrint may inform patients with ER-positive or PR-positive, HER2-negative breast cancer and 0-3 positive lymph nodes and their clinicians whether or not to forego adjuvant chemotherapy. Although MammaPrint can be used to identify patients with high clinical risk who may receive limited benefit from chemotherapy, women with low clinical risk of recurrence did not benefit from chemotherapy, regardless of their MammaPrint risk group. Thus, ASCO does not recommend the use of MammaPrint for patients with low clinical risk. 

Posted 11/16/17

References

Krop I, Ismaila N, Andre F, et al.  “Use of Biomarkers to Guide Decisions on Adjuvant Systemic Therapy for Women With Early-Stage Invasive Breast Cancer: American Society of Clinical Oncology Clinical Practice Guideline Focused Update.” Journal of Clinical Oncology 35, no. 24 (August 2017) 2838-2847.

Harris L, Ismaila N, McShane L, et. al. "Use of Biomarkers to Guide Decisions on Adjuvant Systemic Therapy for Women With Early-Stage Invasive Breast Cancer: American Society of Clinical Oncology Clinical Practice Guideline." Journal of Clinical Oncology 34, no. 10 (April 2016) 1134-1150.

Cardosa F, Van t’ veer LJ, Boegerts J, et al. “70-Gene Signature as an Aid to Treatment Decisions in Early-Stage Breast Cancer.” New England Journal of Medicine 2016; 375:717-729 August 25, 2016.