Comparative Analysis of Clinical and Molecular Characteristics in Invasive Ductal Carcinoma of the Breast

Abstract

Purpose Breast cancer is a complex and diverse disease with several molecular subgroups and clinical manifestations. In India, the prevalence of breast cancer is increasing. Infiltrating ductal carcinoma is the most prevalent histologic form of breast cancer. It is necessary to investigate all aspects of breast cancer using various analytical approaches. Methods We have investigated breast tumors extensively with immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), quantitative polymerase chain reaction (qPCR), and whole-exome sequencing (WES). The study consisted of 160 cases of invasive ductal carcinoma (IDC) in which Whole Exome Sequencing was performed in ten samples of IDC. Results The findings demonstrated that HER2 amplification levels were considerably lower in patients with low protein expression (IHC score 0 or 1+) compared to those with high expression (IHC score 3+). Gene amplification was seen in 41.3% of patients with moderate protein expression (IHC score 2+). We have also found that there was a high level of concordance between HER2 FISH and HER2/neu gene amplification in Group 1 (34%), Group 2(1%), Group 3 (1%), Group 4 (6%) and Group 5(58%) with significant p-value (p ≤ 0.05). The WES results demonstrated that the triple-negative breast cancer sample showed several SNPs and indels in genes including TP53, BRCA1, and MYCN, whereas the HER2 positive (HER2 + 3) group had substantial SNPs in PAK1, CUL3, and TP53. Conclusion Our study sheds light on the clinical and molecular aspects of IDC of the breast. These findings could potentially have effects on the diagnosis of disease progression, intervention effectiveness, and survival. Integrating several molecular approaches provided a thorough understanding of breast cancer subtypes and could assist in treatment selection.