Background

In MINDACT trial, 4 risk categories (RC) by clinical (c) and genomic (g) breast cancer (BC) risk 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 the trial primary objective. Recently, a MP g group with excellent prognosis, named ultralow (gUL), has been described (15% in MINDACT). However, few data exist regarding the distribution of these 4 MINDACT RC and the proportion of gUL in the invasive lobular carcinoma (ILC) population. Moreover, association of Ki67 values and MP RC is rarely studied, both in general population and, particulary, in ILC pts. We aimed to address all these questions by comparing our series of invasive carcinoma of non-special type (NST) and ILC pts in whom MP was performed.

Methods

Pts with ER+/PgR±/HER2- early BC diagnosed from 2012 to 2020 in our institution and with MP data were reviewed. Clinical risk was defined as in the MINDACT trial; genomic risk defined by MP score (UL score: 0.355 to 1.00).

Results

152 pts were identified. NST: 85%, ILC: 15%. Median age NST/ICL: 54/59 years. Histological grade (HG) 1/2/3 (NST vs ILC) 19%/73%/8% and 18%/82%/0%, respectively. UL (g) risk: 17 (13.2%) in NST, 3 (13%) in ILC. The distribution of RC is summarized in the table [UL and Low-non-Ultralow (LNUL) combined for small numbers in ILC]. Median Ki67 value by (g) RC (gLow vs High) in the NST group were 12 and 20: (p<0.001). Of note, in ILC pts median Ki67 was 15 for both MP (g) RC (p=0.77).

Table: 63P

Conclusions

Our results suggest a trend for lower genomic RC in ILC population compared to NST pts. As expected, median Ki67 values correlated with MP genomic categories in overall population and in NST but, intriguingly, not in ILC pts. The small number of pts in this latter group limits results. Further data in wider populations are needed to establish the true association of Ki67 with MP categories in ILC population.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

E. Zamora: Financial Interests, Personal, Invited Speaker, Review session for medical oncologists: Eisai, Lilly; Other, Registration to ESMO Congress 2022 (virtual): Novartis; Other, Registration to: Eisai. G. Villacampa: Financial Interests, Personal, Invited Speaker, Invited speaker in a course: MSD; Financial Interests, Personal, Advisory Board: AstraZeneca; Financial Interests, Personal, Invited Speaker, Invited speaker in an internal training: Pierre Fabrer, GSK; Financial Interests, Personal, Invited Speaker, Internal discussion about the interpretation of some published results: Pfizer; Financial Interests, Personal, Other, Collaborations with specific projects: Reveal Genomics. C. Saura Manich: Financial Interests, Personal, Advisory Board: AX'Consulting, AstraZeneca, Daiichi Sankyo, Eisai, Exact Sciences, Exeter Pharma, F. Hoffmann - La Roche Ltd., Gilead, ISSECAM, Lilly, MediTech, Medical Statistics Consulting, Merck Sharp & Dohme, Novartis, Pfizer, Philips, Piere Fabre, PintPharma, Puma, Roche Farma, Sanofi-Aventis, Seagen, Solti, Zymeworks, Pharmalex Spain SLU; Financial Interests, Personal, Expert Testimony: AX's Consulting SARL, Boehringer Ingelheim, Bristol Meyers Squibb, INDITEX, Merck Sharp & Dohme España, Novartis, SACE Medhealth SL, Simon Kucher &Partners SL, Genentech, Innoup, Millenium, Sanofi, Seattle Genetics; Financial Interests, Personal, Other, SC: Byondis B.V., German Breast Group, Glaxo, International Breast Cancer Study Group (IBCSG), Macrogenics, Medsir, Menarini, Merus, Merus, Netherlands Cancer Institute (NKI), Queen Mary (University of London), Seagen, Synthon Biopharpaceuticals; Financial Interests, Institutional, Research Grant: AstraZeneca, Bayer Pharma, Boehringer Ingelheim, Bristol Myers Squibb (BMS), Cytomx Therapeutics, Daiichi Sankyo, Eli Lilly and Company, F. Hoffmann-La Roche Ltd., Genentech, Glaxosmithkline, Immunomedics, Innoup Farma, International Breast Cancer Study Group (IBCSG), Macrogenics, Medica Scientia Innovation Research, Menarini Ricerche, Merus, Novartis, Pfizer, Puma, Roche, Sanofi-Aventis, Seattle Genetics, SOLTI; Financial Interests, Institutional, Invited Speaker: Byondis B.V.; Non-Financial Interests, Member: Spanish Society of Medical Oncology (SEOM), American Society for Clinical Oncology (ASCO), SOLTI group (Academic research group in breast cancer), Geicam (Spanish Breast Cancer Research Group), American Association for Cancer Research (AACR). M. Bellet-Ezquerra: Financial Interests, Personal, Advisory Board: Pfizer, Novartis, Lilly, Stemline-Menarini; Other, Speaker'sBureau and Travel Expenses: Pfizer; Other, Speaker's Bureau: Novartis, Lilly. All other authors have declared no conflicts of interest.