Encoded by the CDX2 homeobox gene, the CDX2 protein assumes the role of a pivotal transcription factor localized within the nucleus of intestinal epithelial cells, orchestrating the delicate equilibrium of intestinal physiology while intricately guiding the precise development and differentiation of epithelial tissue. Emerging research has unveiled that positive immunohistochemical expression of this protein shows that the CDX2 gene exerts a potent suppressive impact on tumor advancement in colorectal cancer, impeding the proliferation and distant dissemination of tumor cells, while the inhibition or suppression of CDX2 frequently correlates with aggressive behavior in colorectal cancer. In this study, we conducted an immunohistochemical assessment of CDX2 expression on a cohort of 43 intraoperatively obtained tumor specimens from patients diagnosed with colon cancer at Colțea Clinical Hospital in Bucharest, between April 2019 and December 2023. Additionally, we shed light on the morphological diversity within colon tumors, uncovering varying differentiation grades within the same tumor, reflecting the variations in CDX2 expression as well as the genetic complexity underlying these tumors. Based on the findings, we developed an innovative immunohistochemical scoring system that addresses the heterogeneous nature of colon tumors. Comprehensive statistical analysis of CDX2 immunohistochemical expression unveiled significant correlations with known histopathological parameters such as tumor differentiation grades (p-value = 0.011) and tumor budding score (p-value = 0.002), providing intriguing insights into the complex involvement of the CDX2 gene in orchestrating tumor progression through modulation of differentiation processes, and highlighting its role in metastatic predisposition. The compelling correlation identified between CDX2 expression and conventional histopathological parameters emphasizes the prognostic significance of the CDX2 biomarker in colon cancer. Moreover, our novel immunohistochemical scoring system reveals a distinct subset of colon tumors exhibiting reserved prognostic outcomes, distinguished by their “mosaic” CDX2 expression pattern.

Breast cancer is one of the more frequently diagnosed cancers leading to death in women, and, like other tumor types, it is heterogeneous in its immunophenotype. It harbors mutations that modify tumor aggressiveness, therapy responses, residual disease, drug resistance, and relapse rates in advanced stages. This study aims to assess the mutational status of G2 and G3 tumors using next-generation sequencing (NGS) on initial tissue biopsies, liquid biopsies, and mastectomy specimens. The histopathological (HP) diagnosis for the 32 selected cases was established via Hematoxylin–Eosin (HE) staining by two observers. For the immunohistochemical (IHC) testing of estrogen receptor (ER), progesterone receptor (PGR) and human epidermal growth factor receptor 2 (HER2), we used the Ventana BenchMark Ultra. Ki67 testing was conducted using Bond-III from Leica. For cases with a score of 2+, gene amplification was assessed by silver-enhanced in situ hybridization (ISH) (SISH; Inform HER2 Dual ISH) on Ventana BenchMark Ultra. NGS analysis was initially performed on biopsies and plasma, and later on mastectomy specimens. After automated deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) extraction, concentrations were measured using the Invitrogen Qubit system. Libraries were created using Oncomine systems, and sequencing and analysis were done with the Ion Torrent system. Most tumors were graded as G3 (19 cases), with Luminal A being the predominant molecular subtype, and a significant number displayed HER2/HER2-low characteristics (24 out of 32 cases). The NGS assessment showed that phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) mutations were the most frequent across all sample types. A significant limitation was the high number of invalid plasma tests due to pre-analytical handling errors or transport issues. Nonetheless, plasma testing (liquid biopsy) proved useful for monitoring tumor evolution and assessing residual disease.