Background: Breast cancer is the most frequently diagnosed life-threatening malignancy
among women, across the globe. HER2 positive is a distinct breast cancer subtype, on account of its
unique biology and physiological behavior.
Results: Amplification of HER2 oncogene/polysomy 17 leads to HER2 overexpression that is a significant
causal implication in HER2 positive breast cancer. HER2 gene variants, as well as other
genes/gene variants, are involved in its overexpression, disease prognosis and in predicting the susceptibility
towards HER2 positive breast cancer. Trastuzumab (Herceptin) is the most commonly used
therapy for treating patients with HER2 positive status. Genomic alterations are incriminated in the development
of trastuzumab-resistance, which influences the response towards trastuzumab-therapy.
Conclusion: In the current review article, we have summarized the genomic alterations that are responsible
for overexpression of HER2 and therefore, increased risk of breast cancer. In addition, the
gene variants affecting response towards trastuzumab-therapy have also been discussed.