PROGNOSTIC GENETIC TEST REDUCE ADJUVANT CHEMOTHERAPY USE 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.