Keyword: Breast Cancer

ABSTRACT: Introduction: Neutrophil extracellular traps (NETs) are web-like structures composed of decondensed chromatin and neutrophil granule proteins. Accumulating evidence suggests that NETs are involved in tumor progression, invasion, and metastasis in breast cancer. Therefore, investigating changes in NET formation during anticancer therapy and their potential use as a marker of treatment efficacy is of particular interest.
Objective: To evaluate the dynamics of induced NET formation during neoadjuvant endocrine therapy (NET) in patients with hormone receptor (HR)-positive breast cancer and to determine its association with changes in primary tumor size.
Materials and Methods: The study included 50 patients with stage II–III HR-positive breast cancer who received neoadjuvant endocrine therapy for 3–6 months. Endocrine therapy included letrozole and toremifene (Fareston); in a subset of patients, toremifene was combined with ovarian suppression using triptorelin (Diphereline). Induced NET formation in peripheral blood was assessed using the method developed by I.I. Dolgushin with pyrogenal stimulation, followed by May–Grünwald azure-eosin staining and microscopy. NET-forming neutrophils were counted per 100 neutrophils. Primary tumor size was assessed by ultrasonography (US) and mammography (MMG). Statistical analysis included the Wilcoxon signed-rank test, Friedman test, and Spearman’s rank correlation.
Results: In the three-time-point analysis of patients with serial measurements (n=32), the median number of induced NETs was 2 [0; 15] at baseline, 0 [0; 1.5] after 3 months, and 2 [0; 6] after 6 months of neoadjuvant endocrine therapy; the overall change did not reach statistical significance (p=0.051). After 3 months of treatment, a reduction in primary tumor size was observed. On US, the median tumor size decreased from 25.0 [22.0; 36.25] to 21.0 [18.0; 27.25] mm (p<0.001), while on MMG it decreased from 29.0 [21.5; 36.5] to 24.0 [18.0; 30.5] mm (p=0.049). The median relative reduction was 16.0% and 11.8%, respectively. No statistically significant correlation was found between changes in NET formation and the percentage change in tumor size after 3 months: US, rₛ=0.139, p=0.351; MMG, rₛ=0.015, p=0.918.
Conclusion: Changes in induced NET formation were observed during neoadjuvant endocrine therapy, with the lowest values recorded after 3 months of treatment. However, no association was established between changes in NET formation and the degree of primary tumor size reduction. These interim findings do not support the use of induced NET dynamics as a standalone marker of radiological response to neoadjuvant endocrine therapy and warrant further evaluation in a larger cohort.

ABSTRACT: Tumor cells release biomarkers such as CD44 into the bloodstream, offering opportunities for minimally invasive monitoring of tumor progression. However, conventional analytical methods often suffer from insufficient sensitivity and a limited dynamic range, which hinders reliable detection of such biomarkers in complex biological fluids. Optical fiber biosensors are particularly attractive alternatives, offering high sensitivity, low cost, chemical inertness, and diverse surface functionalization strategies, making them well suited for detecting clinically relevant circulating tumor biomarkers that require sensitive, quantitative analysis. CD44, a cell adhesion glycoprotein whose soluble form (solCD44) is elevated in several cancers including breast cancer (BC), was selected as a model biomarker for this study owing to its well-established diagnostic relevance.
Here, we report the development of a graphene oxide-coated fiber-optic biosensor based on a semi-distributed interferometric sensing platform for the highly sensitive detection of solCD44. A total of 46 sensors were fabricated and characterized for their sensitivity to refractive index changes in the surrounding medium. The sensor surface was subsequently functionalized with anti-CD44 antibodies, and successful biofunctionalization together with antibody specificity was confirmed using several complementary techniques, including atomic force microscopy (AFM) and ELISA.
The optimized biosensor exhibited a wide dynamic detection range, spanning attomolar concentrations up to 100 nM, with a limit of detection (LOD) as low as 175 aM in spiked serum. Specificity was confirmed by comparison with non-functionalized sensors and healthy control samples. To validate its practical clinical applicability, the biosensor was further tested in human serum samples from breast cancer patients, showing significantly higher signal in cancer patients than in healthy controls. Successful detection of solCD44 in urine additionally demonstrated the biosensor's compatibility with multiple biological matrices. Together, these findings establish this fiber-optic biosensor as a promising platform for highly sensitive, label-free, and minimally invasive detection of cancer biomarkers, with strong potential for clinical translation and point-of-care diagnostic systems.

ABSTRACT: Introduction. The expansion of indications for trastuzumab deruxtecan following the DESTINY-Breast06 trial has increased the clinical relevance of minimal HER2 membrane staining that was previously included within the HER2 0 category. In the current CAP protocol, HER2 0 is further subdivided into 0 with no membrane staining and 0+ with membrane staining, corresponding to the HER2-ultralow phenotype. Conventional HER2 immunohistochemistry (IHC) has historically been focused on identifying HER2 overexpression, whereas assessment of very low levels of HER2 staining is less reproducible. This places greater emphasis on the distinction between HER2 0 with no detectable expression (HER2-null), HER2-ultralow, and HER2 IHC 1+.
Objective. To determine the frequency of HER2-ultralow expression among invasive breast carcinomas initially classified as HER2 0, to assess patterns of reclassification on repeat review, and to evaluate concordance between the initial and repeat standard HER2 status.
Materials and Methods. A retrospective single-center study included 241 cases of invasive breast carcinoma without prior neoadjuvant therapy diagnosed between January and July 2026. Initial HER2 status was assessed by IHC in routine clinical practice according to the 2023 ASCO/CAP recommendations, and all slides were subsequently reviewed by a second pathologist. IHC was performed using the HER2 antibody clone 4B5 (Ventana). During repeat assessment, HER2 0 cases were further subclassified as HER2-null or HER2-ultralow. For concordance analysis, both subcategories were combined within the conventional HER2 0 category. Overall percent agreement and Cohen’s κ coefficient were calculated. Clinicopathological associations were evaluated in an exploratory analysis.
Results. The initial HER2 distribution was as follows: 0 in 112/241 cases (46.5%), 1+ in 66 (27.4%), 2+ in 24 (10.0%), and 3+ in 39 (16.2%). Following repeat review, HER2-ultralow expression was identified in 55/241 cases (22.8%). Among the 112 tumors initially classified as HER2 0, 61 (54.5%) were categorized as HER2-null, 44 (39.3%; 95% CI, 30.7–48.5%) as HER2-ultralow, and 7 (6.2%) were reclassified as HER2 1+. Standard HER2 status changed in 22/241 cases (9.1%), with 20/22 discrepancies (90.9%) occurring at the HER2 0↔1+ boundary. Overall agreement was 90.9%, with a Cohen’s κ of 0.864. Among tumors initially classified as HER2 0 with known hormone receptor (HR) status, HER2-ultralow expression was identified in 35/80 (43.8%) HR-positive tumors and 2/16 (12.5%) HR-negative tumors (OR, 5.44; 95% CI, 1.16–25.55; p=0.024). No statistically significant differences were observed according to histologic grade or Ki-67 proliferation index.
Discussion and Conclusions. HER2-ultralow expression was identified in 39.3% of tumors initially classified as HER2 0, a proportion comparable with that reported in recent retrospective studies. Changes in HER2 classification occurred predominantly at the HER2 0↔1+ boundary, highlighting the diagnostic vulnerability of the lower range of HER2 expression. Although concordance for conventional HER2 categories was high (κ=0.864), this analysis does not assess the reproducibility of distinguishing HER2-null from HER2-ultralow because interobserver agreement specifically at this boundary was not evaluated. These findings emphasize the heterogeneity of the HER2 0 category and support the importance of standardized assessment and explicit reporting of minimal HER2 membrane staining in routine pathologic practice.
 

ABSTRACT: Introduction: Germline mutations in the BRCA1 and BRCA2 genes are an important hereditary risk factor for the development of breast cancer. The spectrum of pathogenic variants of these genes is characterized by pronounced ethnic and population specificity, including the presence of founder mutations. Data on the spectrum of germline BRCA1/BRCA2 variants in the Kazakh population remain limited, which hinders their application in clinical practice and genetic counseling.
Objective: To study the spectrum of germline mutations in the BRCA1 and BRCA2 genes in patients with breast cancer and women with a family history in the Kazakh population and to identify the founder mutation.
Materials and Methods: The study included 544 women of Kazakh ethnicity with breast cancer or a family history of cancer. DNA was isolated from peripheral blood lymphocytes according to the manufacturer's protocol. Exons and adjacent intronic regions of the BRCA1 and BRCA2 genes were sequenced by NGS. Variants were classified by clinical significance, and their spectrum and distribution by gene, type, and localization were analyzed.
Results: Of the 544 examined patients, 178 (32.7%) were found to have mutations in the BRCA genes. Mutations in the BRCA1 gene were detected in 35 patients (19.7%), in the BRCA2 gene — in 119 patients (66.8%), and mutations in both genes — in 24 patients (13.5%).
The study identified a total of 125 BRCA gene variants. Sequence analysis revealed 37 pathogenic variants in 81 patients, 83 likely pathogenic variants in 104 patients, 1 likely benign variant in 6 patients, 2 benign variants in 6 patients, and 2 variants of uncertain clinical significance in 2 patients.
Among BRCA1 gene variants, the most common was a deletion of exon 6, detected in 11 patients (6.1%). Deletions of exons 2, 13, and 20 were found in 7 patients each (3.9%), while deletions of exons 8 and 23, as well as variants BRCA1 c.3214delC and BRCA1 c.1044_1045insC, were found in 3 patients each (1.7%).
Among the identified BRCA2 gene variants, the most common was a deletion of exon 16, detected in 37 patients. The variant c.24_27delGCCAinsCG was identified in 15 patients, c.2600_2601insA in 12 patients, and c.9241_9242insA in 11 patients.
Conclusions: The spectrum of germline BRCA1/BRCA2 mutations in the Kazakh population is characterized by a predominance of BRCA2 gene variants. Deletion of exon 16 of the BRCA2 gene was identified as a founder mutation.