Outcomes of non-metastatic HER-2 positive breast cancer before and after the introduction of anti-HER-2 therapy: a retrospective study from a tertiary Egyptian center

Abstract Background HER-2 positive breast cancer accounts for 15–20% of cases and is associated with aggressive behavior and poor prognosis. Anti-HER-2 therapy, including trastuzumab and pertuzumab, has improved outcomes in Western populations; however, real-world data in Egyptian patients remain limited. This study evaluated pathological response, disease-free survival (DFS), and overall survival (OS) among Egyptian patients with non-metastatic HER-2 positive breast cancer treated before and after the introduction of anti-HER-2 therapy. Methods We retrospectively analyzed 200 female patients with non-metastatic HER-2 positive breast cancer treated in two treatment eras: before the introduction of anti-HER-2 therapy (2014–2016, n = 100) and after its introduction (2020–2022, n = 100). Patients in the later era received trastuzumab alone or trastuzumab plus pertuzumab in the neoadjuvant or adjuvant setting. Outcomes included pathological complete response (pCR), DFS, OS. Survival outcomes were assessed using Kaplan–Meier analysis and compared using the log-rank test. Univariable and multivariable Cox proportional hazards regression analyses were performed for DFS and OS. Results Anti-HER-2 therapy was associated with a higher pCR rate among patients who received neoadjuvant treatment (40.0% vs. 10.3%, p < 0.001) and more favorable postoperative tumor and nodal staging. The median follow-up duration was 51.2 months in the non-anti-HER-2 group and 40.0 months in the anti-HER-2 group. During follow-up, disease recurrence occurred in 60% of patients in the non-anti-HER-2 group compared with 17% in the anti-HER-2 group ( p < 0.001), while overall mortality was 13% in the anti-HER-2 group compared with 59% in the non-anti-HER-2 group ( p < 0.001). Multivariable Cox regression analysis showed that anti-HER-2 therapy was associated with improved DFS (HR 0.274, 95% CI 0.108–0.697; P = 0.007) and OS (HR 0.260, 95% CI 0.093–0.728; P = 0.010). Conclusion In this retrospective study of Egyptian patients with non-metastatic HER-2 positive breast cancer, treatment in the later era, when anti-HER-2 therapy was available, was associated with higher pathological response rates and improved DFS and OS. However, given the historical-cohort design and differences in baseline characteristics and treatment strategies between the two eras, these findings cannot establish a causal effect of anti-HER-2 therapy alone. Larger multicenter studies are warranted to further evaluate outcomes and address treatment-era and selection-related confounding in the Egyptian setting.