Recurrence Score Predicts Chemotherapy Benefit In HER2-Negative Breast Cancer Patients

The 21-gene Recurrence Score significantly predicts 3-year disease-free survival in HER2-negative breast cancer patients

medwireNews: The validated 21-gene Recurrence Score (RS) assay can be used to guide the use of adjuvant chemotherapy in patients with HER2-negative, hormone receptor (HR)-positive breast cancer, suggest disease-free survival (DFS) findings from the PlanB trial.

The study included node-positive patients and node-negative patients with high-risk disease features, such as age less than 35 years at diagnosis, or T2 or grade 2 or 3 disease, who had undergone complete resection and axillary dissection where necessary.

The 348 patients with a low RS score of 11 or less had a 3-year DFS rate of 97.4% despite being assigned to receive only endocrine therapy after surgery. This rose to 98.4% when only low RS score patients with pN0–1 disease were included, report Oleg Gluz, from the Evangelical Hospital Bethesda in Moenchengladbach, Germany, and co-workers.

“Even with an only 3-year follow-up, such a high rate of DFS almost excludes possible benefit from adjuvant chemotherapy”, they write in the Journal of Clinical Oncology.

The 1078 patients with an intermediate RS score of 12–25 who received anthracycline-based or anthracycline-free chemotherapy had a 97.8% DFS rate at 3 years, whereas the rate fell to 91.9% for the 409 patients with an RS score greater than 25. The corresponding values for patients with pN0–1 disease within these groups were 97.5% and 94.9%.

“These are the first prospective data to our knowledge to report clinical outcome both in patients with node-negative and with node-positive [breast cancer] where the RS results had been used in decision making in a large phase III trial”, the researchers say.

“These findings confirm the recently published prospective TAILORx (Trial Assigning IndividuaLized Options for Treatment) results in node-negative patients and retrospective analyses of prospective clinical trials”, they add.

There was “significant disagreement” in tumour grade assessment between the local and central pathology review findings, with overall concordance of just 68.0%, falling to 66.3% for locally HR-positive tumours.

“As adjuvant chemotherapy is strongly recommended in patients with [grade] 3 tumors, there is an urgent need for additional work on how to further standardize grade assessment in HR-positive breast cancer”, Oleg Gluz et al comment.

They say their study “emphasizes that RS may help to make treatment decisions more homogenous and reliable, independent of where patients are treated.”

Multivariate analysis confirmed that nodal status, central and local grade, and RS score all significantly and independently predicted DFS.

Reference

Gluz O, Nitz UA, Christgen M, et al. West German Study Group phase III PlanB trial: First prospective outcome data for the 21-gene Recurrence Score assay and concordance of prognostic markers by central and local pathology assessment. J Clin Oncol 2016; Advance online publication 29 February. doi: 10.1200/JCO.2015.63.5383

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