فهرست نشریات علمی دسترسی آزاد ایران

Background and Objective: Breast cancers that overexpress the HER2 receptor tend to exhibit moreaggressive behavior compared to other breast cancer subtypes. As a result, HER2 status plays a critical rolein prognosis and treatment planning. Recently, increasing attention has been given to differences amongHER2 -Negative cases, which include three subgroups: 0, 1+, and 2+ (with Negative results on FISH or CISHtests), collectively referred to as “HER2-low.” Emerging evidence suggests that these subgroups may differbiologically. This study aimed to investigate the clinical and pathological characteristics of these three HER2-Negative subgroups, with a particular focus on tumor features.Materials & Methods: This retrospective, cross-sectional analytical study included data from 3,745patients with HER2-Negative breast cancer. Categorical variables were analyzed using the Chi-Square test,while continuous variables were assessed based on normality with appropriate test.Results: The mean age of the patients was 50.96 ± 11.37 years. Comparative analysis showed thatpatients in the HER2-intermediate ISH-Negative group were significantly younger than those in the othertwo groups (p = 0.03). Tumor size was smaller, and the mean Ki-67 index was higher in this group comparedto the others (p < 0.001). Additionally, grade 3 tumors (22.1%), positive surgical margins (9%), andmetastasis (11.1%) were more common in the HER2-intermediate ISH-Negative group. This group also hadthe highest recurrence (26.1%) and mortality rates (24.7%). Conversely, the HER2-zero group had the largestaverage tumor size (28.74 ± 19.59 mm), the highest lymph node involvement (53.2%), and the greatestincidence of lymphovascular invasion (58.6%). The HER2-low 1+ group appeared to be the least aggressive,showing the lowest rates of grade 3 tumors (13.7%), positive margins (4.3%), and recurrence (11.5%).Regarding treatment, the majority of HER2-zero and HER2-low 1+ patients received adjuvant chemotherapy(62.3% and 51.3%, respectively), while neoadjuvant chemotherapy was more commonly administered topatients in the HER2-intermediate ISH-Negative group (52%).Conclusion: Based on the findings of this study, patients in the HER2-intermediate ISH-Negative groupexhibited more aggressive tumor characteristics and poorer outcomes compared to the other HER2 -Negative subgroups. In contrast, the HER2-low 1+ group demonstrated the most favorable prognosis. Theseresults suggest that patients with HER2-intermediate ISH-Negative status may benefit from closermonitoring and more frequent follow-up to improve clinical outcomes.