63P Ki67 values and MammaPrint (MP) genomic risk in early breast cancer: Correlation by ductal vs lobular histology

In MINDACT trial, 4 risk categories (RC) by clinical (c) and genomic (g) breast cancer (BC) were defined. The study showed that the cHigh/gLow group without chemotherapy (CT) had a 94.8 % (CI 95% 92.9-96-2) 5-year Distant Metastases Free Survival (DMFS), so meeting trial primary objective. Recently, MP g with excellent prognosis, named ultralow (gUL), has been described (15% in MINDACT). However, few data exist regarding distribution of these RC proportion gUL invasive lobular carcinoma (ILC) population. Moreover, association Ki67 values is rarely studied, both general population and, particulary, ILC pts. We aimed to address all questions comparing our series non-special type (NST) pts whom was performed. Pts ER+/PgR±/HER2- early BC diagnosed from 2012 2020 institution reviewed. Clinical defined as trial; score (UL score: 0.355 1.00). 152 identified. NST: 85%, ILC: 15%. Median age NST/ICL: 54/59 years. Histological grade (HG) 1/2/3 (NST vs ILC) 19%/73%/8% 18%/82%/0%, respectively. UL risk: 17 (13.2%) NST, 3 (13%) ILC. summarized table [UL Low-non-Ultralow (LNUL) combined for small numbers ILC]. value (gLow High) NST 12 20: (p<0.001). Of note, median 15 (p=0.77). Table: 63POverall (n=151)NST (n=129)CLI (n=22)cLow-gLow (N/%)61 (40.4)51 (39.5)10 (45.5)cLow-gHigh (N/%)39 (25.8)36 (27.9)3 (13.6)cHigh-gLow (N/%)36 (23.8)28 (21.7)8 (36.3)cHigh-gHigh (N/%)15 (9.9)14 (10.8%)1 (4.5) Open new tab Our results suggest trend lower compared As expected, correlated overall but, intriguingly, not number this latter limits results. Further wider populations are needed establish true