Abstract 284P
Background
HER2-low breast cancer has emerged as a novel subgroup defined as HER2 1+ or 2+ with non-amplified FISH, representing a distinct entity within breast cancer classification. Understanding the systemic recurrence patterns in this subgroup, particularly regarding immunohistochemical (IHC) characteristics such as estrogen and progesterone receptors, is crucial for elucidating its clinical behavior.
Methods
A retrospective analysis was conducted using logistic regression to examine different patient subgroups with varying characteristics related to breast cancer, focusing primarily on the assessment of hormonal receptors and HER2 status. To compare the variables, the chi-square test was employed, and odds ratios were calculated along with their corresponding p-values to determine statistical significance. Additionally, the frequency of HER2 low occurrence in the Mexican population at a center in the northern region of the country was investigated.
Results
A total of 698 breast cancer patients were included, of which 261 (37.39%) met the HER2-low criteria. Among these, 209 (80.07%) were hormone-sensitive, while 52 (19.93%) were not. No relationship was found regarding systemic recurrence in the HR+ & HER2-low group (OR: 0.45; 95% CI: 0.118 - 1.710, p=0.241) nor in the HR- & HER2-low group (OR: 2.03; 95% CI: 0.205 - 19.951, p=0.546), indicating that having HER2-low status does not confer a higher likelihood of recurrence. However, we found a significant relationship between systemic recurrence and IHC only in the triple-negative group (OR: 2.54; 95% CI: 1.070 - 6.030, p=0.034).
Conclusions
In conclusion, no significant HER2-low status association with systemic recurrence was found in breast cancer patients, irrespective of hormone receptor status. However, a notable correlation is observed between immunohistochemical profiles and recurrence, especially in triple-negative cases. Emphasizes the need for comprehensive immunohistochemical profiling for precise risk assessment and personalized treatments. Further research is needed to clarify underlying molecular mechanisms and develop targeted therapies for HER2-low and triple-negative breast cancer subtypes.
Legal entity responsible for the study
Centro Estatal de Cancerología Chihuahua.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.