Genomic-based signatures are implemented in clinical practice to guide adjuvant treatment strategy in early breast cancer patients with luminal tumors. One of the main signatures, the PAM50-based Prosigna assay classifies patients into 3 risk categories based on their score of recurrence, thus providing clear guidance in low or high risk tumors. This study aimed at assessing in real life the proportion of patients with intermediate (ITD) risk results with the Prosigna assay, their tumor profile and the factors influencing treatment decision.
This monocentric retrospective study was conducted in 107 patients with luminal early-stage breast cancer treated at Oscar Lambret Cancer Center (Lille, France). Their tumors were analyzed with the Prosigna assay from July 2016 through April 2018.
The Prosigna assay classified 15% of the patients in the low risk group, 41% were high risk, and 44% ITD risk. In this group, approximately one third were node negative and two third node positive. The tumor profiles with the highest proportion of ITD risk results had the following characteristics: 14≤Ki67≤20% and grade 2 in node negative or positive patients, or Ki67<14% and grade 2 in node positive patients (Table). 83% of the patients with an ITD risk result (39 of 47) were spared chemotherapy. Among them, 34 had luminal A and 5 luminal B tumors. Among the 8 patients proposed chemotherapy, luminal A and B tumors were evenly split. The main determinant of this decision was an estimated 10-year risk of relapse over 10 or 11%. Table: Prosigna risk groups distribution within patients’ main tumor profiles.Table: 213P
|Prosigna risk groups|
|Main Tumor Profiles (99 of 107 patients)||n||%||n||%||n||%||Total (n)|
|14≤Ki67≤20% - G2 - N0||5||33||7||47||3||20||15|
|14≤Ki67≤20% - G2 - N1||0||10||59||7||41||17|
|Ki67<14% – G2 - N0||6||60||3||30||1||10||10|
|Ki67<14% – G2 - N1||0||13||65||7||35||20|
|Ki67>20% – G2 - N0||2||17||4||33||6||50||12|
|Ki67>20% – G2 - N1||0||1||9||10||91||11|
|Ki67>20% – G3 - N0 - T1||0||3||43||4||57||7|
|Ki67<14% – G1 - N1||2||29||4||57||1||14||7|
G: grade; N0/N1: node negative / positive (1 to 3); T1: tumor size ≤ 20mm
Our study showed that a significant proportion of patients were classified in the intermediate risk group, and most were spared chemotherapy. A specific guidance is needed in this risk group.
Clinical trial identification
Legal entity responsible for the study
Centre Oscar Lambret.
Has not received any funding.
All authors have declared no conflicts of interest.