Impact of 70-Gene Signature on Adjuvant Chemotherapy Decisions in Breast Cancer
In a Dutch observational study reported in the Journal of Clinical Oncology, Kuijer et al found that use of the MammaPrint 70-gene signature (70-GS) test changed physician-intended recommendations to administer adjuvant chemotherapy in half of patients with early-stage estrogen receptor–positive breast cancer. A Dutch guideline suggests use of validated gene-expression profiles in patients with estrogen receptor–positive early-stage disease without overt lymph node metastases. In the Netherlands, the 70-GS test accounts for 97% of use of gene-expression tests.
Study Details
In the prospective multicenter study, physicians of patients aged < 70 years who had undergone surgery for estrogen receptor–positive early-stage breast cancer were asked whether they intended to give adjuvant chemotherapy before using the 70-GS test and again after the test result was available.
A total of 660 patients from 33 hospitals were enrolled between October 2013 and December 2015. Patients had a median age of 57 years; 405 were postmenopausal women with unifocal HER2-negative low-grade tumors > 2 cm or intermediate-grade tumors of 1 to 2 cm without axillary node involvement (pN0 or pN1mi).
Advice Before and After Testing
Before use of the 70-GS test, oncologists recommended adjuvant chemotherapy on the basis of conventional clinicopathologic characteristics in 41% of patients and advised against it in 16%. In the remaining 43%, no preliminary recommendation was made because physicians preferred to await the test result.
The 70-GS test indicated a low-risk profile in 56% of patients with initial recommendation for chemotherapy and in 59% of those for whom it was not recommended (κ = 0.02 [no agreement to slight agreement], 95% confidence interval = –0.08 to 0.11). Preliminary advice was in agreement with the 70-GS risk category in 48% of patients.
After the 70-GS test result was available, preliminary advice was changed in 51% of patients with a recommendation before testing. After test results were available, the final chemotherapy recommendation of the physician agreed with the 70-GS result in 96% of patients.
The investigators concluded: “In this prospective, multicenter study in a selection of patients with [estrogen receptor–]positive, early-stage breast cancer, 70-GS use changed the physician-intended recommendation to administer [chemotherapy] in half of the patients.”
The study was supported by Agendia NV.
Thijs van Dalen, PhD, of Diakonessenhuis, Utrecht, is the corresponding author of the Journal of Clinical Oncology article.
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®.
