Deciphering HER2-low breast cancer (BC): insights from real-world data in early stage breast cancer.

Background

Human epidermal growth factor receptor 2 (HER2)-low has emerged as a potential new entity in breast cancer (BC). Data on this subset are limited, and prognostic results are controversial, evidencing the need of further data in a BC real-world cohort.

Methods

Patients with HER2-negative stage I-III BC diagnosed between 2006 and 2016 were retrospectively reviewed in a single cohort from the Catalan Institute of Oncology Badalona. Demographics and clinicopathological characteristics were examined via medical charts/electronic health records. We aim to describe and compare HER2-0/HER2-low populations through Chi-square or Fisher test, and explore its prognostic impact using Kaplan-Meier curves and Cox regression models.

Results

From a cohort of 1755 BC patients, 1401 invasive HER2-negative, stage I-III cases were evaluated. 87% were hormone receptor (HR)-positive versus 13% triple negative (TNBC). Overall, 43% were HER2-0 and 57% HER2-low (61% immunohistochemistry (IHC) 1+ and 39% IHC 2+). Comparing HER2-low versus HER2-0, HER2-low showed higher proportion of estrogen receptor (ER)-positive (91.6% vs 79.9%,

Conclusion

HER2-low was significantly associated with HR-positive disease, whereas HER2-0 group had higher incidence of TNBC, histological grade III and higher Ki67%. Although HER2-low group was associated with longer TTDR and improved BC-related survival, these findings could be explained by the greater proportion of favorable prognostic features in this subgroup compared to HER2-0.

Informations de copyright

© The Author(s), 2024.

Déclaration de conflit d'intérêts

A.P. declares being invited as speaker for GSK, Eisai, and Lilly, travel expenses and congress assistance from Lilly, Gilead, Dr. Reddys, and Pfizer. Member of GEICAM, SEOM, ESMO, and SOLTI societies. A.B.P. declares no conflicts of interest. A.L. declares being invited as speaker for Eisai, Lilly, and Novartis, and travel expenses from Roche, Gilead, and Novartis. Member of GEICAM, SEOM, ESMO, and SOLTI societies. B.C. declares being invited as speaker for BMS, Merck, and MSD. Training grants from BMS, Merck, and MSD. Advisory board: BMS, Merck, and MSD. Member of GEICAM, SEOM, ESMO, and SOLTI societies, and member of the board of directors from TTCC. V.Q. declares being invited as speaker for AstraZeneca, Novartis, Pfizer, and Roche. Advisory board for Roche. Educational activities from GSK, Lilly, and Pfizer and travel expenses from Pfizer and Roche. Member of GEICAM, SEOM, and SOLTI societies. I.T. declares being invited as speaker for Astra Zeneca. Training grants from Novartis, Lilly, ROCHE, and MSD. Member of GEICAM, SEOM, ESMO, and SOLTI societies. E.F declares travel expenses from Pfizer, Lilly, Novartis, and Roche. Speaking fees from Pfizer and advisory board from Novartis. A.F.D. declares being invited as speaker for MSD and Angelini Pharma; and travel expenses from MSD, Lilly, Roche, Merck, and BMS. M.B. declares advisory funding from Eisai, AstraZeneca, Pfizer, Novartis, and travel expenses from Novartis and AstraZeneca. L.B. declares no conflicts of interest. M.R. declares advisory funding from GSK and AstraZeneca, and travel expenses from MSD and AstraZeneca. G.S. declares no conflicts of interest. C.M. declares no conflicts of interest. P.R.M. declares no conflicts of interest. L.P declares no conflicts of interest. E.B. declares no conflicts of interest. A.M.C. declares no conflicts of interest. M.M. declares being invited as speaker for Pfizer, Novartis, and Lilly. Institution research grants from Pfizer and Gilead. Consultant advisory board from Novartis, Lilly, and Menarini. Travel expenses and congress assistance from Gilead, Pfizer, and Roche.