Broader Use of HER2-Based Targeted Therapies Significantly Improves Long-Term Survival in De Novo HER2-Positive Metastatic Breast Cancer

Results from a real-world, population-based study demonstrated that expanded use of human epidermal growth factor receptor 2 (HER2)-targeted systemic therapies significantly improved long-term overall survival (OS) results among patients with de Novo HER2-positive metastatic breast cancer. 

“The proportion of de Novo [HER2-positive breast cancer] has been demonstrated to be increasing, underlining the need to study this distinct subgroup,” stated Nan Ding, PhD, Maastricht University Medical Centre, Maastricht, The Netherlands, and coauthors. While “many new therapeutic options” have become available for patients with HER2-positive metastatic breast cancer in the past 25 years, “it remains uncertain whether the survival benefits observed in the performed clinical trials can consistently be replicated in real-world clinical practice,” as the study authors explained. The aim of this real-world, population-based study was to identify 

In this study, researchers identified 1458 patients from The Netherlands Cancer Registry with de Novo HER2-positive metastatic breast cancer who received HER2-targeted systemic therapy between 2008 and 2017. Researchers assessed OS data in 2-year intervals for key end points including median OS, 5-year OS rate, and 7-year OS rate. 

At a median follow-up of 102 months, median OS increased from 30.9 months to 57.3 months (hazard ratio [HR] 0.49; 95% confidence interval [CI], 46.7 to 68.1; P < .001). The 5-year OS rate increased from 27% to 49% and the 7-year OS rate increased from 17% to 40%. The use of any HER2-targeted therapy increased from 64% to 84% and the use of pertuzumab-based therapy increased by 67%. The rate of patients who underwent surgical resection remained consistent. The rate of radiotherapy as used for primary tumor increased from 16% to 22% and the rate of radiotherapy as used for metastasis increased from 15% to 26%. 

“Incorporating these new agents holds the potential to further extend survival and improve the quality of life for future patients with de Novo [HER2-positive metastatic breast cancer],” concluded Dr Ding et al. 

Source: 

Ding N, Hermans KEPE, van Nijnatten TJA, et al. Overall survival of patients with de Novo HER2-positive metastatic breast cancer in the Netherlands from 2008 to 2017: A population-based cohort study of systemically treated patients. Eur J Cancer. Published online: April 28, 2025. doi: 10.1016/j.ejca.2025.115475