DNA Methylation of a Group of Long Non-Coding RNA Genes at Different Stages of Ovarian Cancer Dissemination.

There are three types of metastases in ovarian cancer: lymphogenous, hematogenous, and peritoneal. Dissemination of the tumor in the peritoneum is directly related with the development of ascites and a poor prognosis. The purpose of this study is to determine changes in the methylation level of a group of long non-coding RNA (lncRNA) genes at different stages of ovarian cancer progression. The methylation level of 7 lncRNA genes (LINC00472, LINC00886, MAFG-DT, SNHG1, SNHG6, TP53TG1, and TUG1) was studied by quantitative methyl-specific PCR in 93 samples of ovarian tumors and 75 paired samples of histologically normal tissue, as well as in 29 peritoneal macroscopic metastases. Using the nonparametric Mann-Whitney test, a significant (p<0.001) increase in the level of methylation of the LINC00886, SNHG1, SNHG6, and TUG1 genes in the tumor tissue was shown. For the LINC00472, LINC00886, and SNHG6 genes, a significant relationship was found with the clinical stage (p≤0.001), as well as with the appearance of metastases for the LINC00472 (p<0.001) and SNHG6 (p=0.005) genes. There was a significant increase in the level of methylation of MAFG-DT and TP53TG1 (p<0.001) genes, as well as a decrease in LINC00886 (p=0.003) in peritoneal metastases relative to the primary focus. Methylation of the LINC00472 and SNHG6 genes can be considered as a factor in initiating ovarian cancer metastasis, and methylation of the LINC00886, MAFG-DT, and TP53TG1 genes as a colonization factor for metastases in the peritoneum. Thus, a relationship between methylation of a group of lncRNA genes at different stages of ovarian cancer dissemination was shown, which is important for understanding the mechanisms of these processes and for developing innovative approaches to ovarian cancer therapy.

Prognostic Significance of Tumor-Associated Inflammation in Renal Cell Carcinoma.

This study analyzed tumor-associated inflammation by assessing the expression of cyclophilin A (CypA) and TNF in samples of kidney tumors of various histological types. It was shown that different histological types of renal cell carcinoma differed by the expression of these proteins. Thus, the highest expression of CypA and TNF was observed in papillary and chromophobe kidney cancer, although no correlation with overall bacterial load was found for these tumors. In the case of clear cell renal cell carcinoma, the expression of proinflammatory factors was observed in only half of the cases and directly correlated with the presence of resident bacteria, serving as a favorable prognostic factor for the disease.

Soluble B7-H3 in Colorectal Cancer.

We present the results of comparative ELISA of the concentration of soluble form of immunity checkpoint B7-H3 (sB7-H3) in the serum of patients with colorectal cancer (CRC) at different stages before treatment and healthy control donors. The analysis revealed a statistically significant difference between the median levels of sB7-H3 in the blood serum of CRC patients (19.66 ng/ml) and healthy donors (16.76 ng/ml) (p=0.0025). ROC analysis showed 62.9% sensitivity and 56.7% specificity for CRC patients (cut-off 17.62 ng/ml; p=0.0028). An association of sB7-H3 levels with tumor progression was revealed. We demonstrated that sB7-H3 levels were significantly lower in patients with regional metastases than in patients without metastases (p=0.039) and that sB7-H3 concentration tends to decrease at the late stages of the disease. Thus, high serum level of sB7-H3 in CRC patients can be a favorable prognostic factor in future.

Dynamics of Soluble Forms of the Immune Checkpoint Components PD-1/PD-L1/B7-H3, CD314/ULBP1, and HLA-G in Peripheral Blood of Melanoma Patients Receiving Blockers of Programmed Cell Death Protein PD-1.

The content of the soluble forms of immune checkpoint components sPD-1, sPD-L1 in blood serum, and sB7-H3, sCD314, sULBP1, sHLA-G in blood plasma of 30 melanoma patients receiving immunotherapy with anti-PD-1 antibodies (nivolumab, pembrolisumab) was measured before and in 4 and 8 weeks after the start of immunotherapy. The control group comprised 70 practically healthy donors. Standard immunoassay kits were used. In melanoma patients, the levels of sPD-L1 and sB7-H3 were significantly higher than in the control group (p<0001), sPD-1 level did not differ from the control, while sCD314 and sHLA-G levels were insignificantly decreased. During therapy, opposite changes in the levels of markers in individual patients were observed, and frequently after the initial increase (or decrease) after the first 4 weeks normalization did occur in the further 4 weeks. No statistically significant associations between the initial levels of markers and direction of their changes during treatment were found, but some trends indicating to the potential benefits from assessment of soluble forms of immune checkpoint proteins for evaluation and monitoring of the efficiency of the therapy with immune checkpoint blockers were revealed: significant decrease of sB7-H3 and sPD-1 levels in the course of treatment, higher initial sPD-1 level in patients with future progression than in those with stabilization or partial effect, and lower progression frequency in patients with increasing sPD-1 and sPD-L1 levels than in those with decreasing markers levels.

Identification of Chimeric NTRK3 Genes in Papillary Thyroid Cancer Cells by Analyzing the Imbalance of the Expression of 5' and 3' mRNA Fragments.

The standard for detecting chimeric genes of neurotrophic receptor tyrosine kinases (NTRK) is next generation sequencing (NGS). However, this analysis is expensive and takes several days. As a rapid screening method for the detection of NTRK3-dependent papillary thyroid cancer, an analysis of the expression imbalance between 5' and 3' NTRK3 mRNA fragments was used (5'/3' RT-PCR). The reference method for detection of NTRK3 rearrangements was fluorescent in situ hybridization (FISH), and the most frequent rearrangements in papillary thyroid cancer were tested using reverse transcription PCR (RT-PCR). Using 5'/3' RT-PCR, 18 samples of papillary thyroid cancer carrying chimeric transcripts of NTRK3 mRNA were detected. The sensitivity of the developed technique was 88.9% and specificity was 99.3%. Thus, a fast and cost-effective method of screening samples of papillary thyroid cancer in paraffin blocks is proposed with acceptable sensitivity and specificity.

The Role of Methylation of a Group of microRNA Genes in the Pathogenesis of Metastatic Renal Cell Carcinoma.

The role of methylation of 9 miRNA genes in the pathogenesis of metastatic clear cell renal cell carcinoma was determined by quantitative methylation-specific PCR (MS-PCR). For 5 genes (MIR125B-1, MIR137, MIR193A, MIR34B/C, and MIR375), a significant correlation of high methylation level with late (III-IV) stages, large size (T3+T4) of the tumor, and metastasis to lymph nodes and/or distant organs was revealed. For another group of genes (MIR125B-1, MIR1258, MIR193A, MIR34B/C, and MIR375), a statistically significant correlation of high methylation level with loss of differentiation in the tumor (G3-G4) was found, and the opposite pattern was found for MIR203A. A total of 7 microRNA genes (MIR125B-1, MIR1258, MIR137, MIR193A, MIR203A, MIR34B/C, and MIR375) were identified, the methylation of which is associated with the progression of metastatic clear cell renal cell carcinoma. For 6 of them (except MIR34B/C) these data were obtained for the first time. Thus, new factors of the development and progression of clear cell renal cell carcinoma were identified as potential biomarkers for the early diagnosis and prognosis of metastatic clear cell renal cell carcinoma.

Differences in Transcriptomic Profiles of Brain and Thyroid Tumors with NTRK Gene Rearrangement.

For tumors with chimeric NTRK genes, entrectinib and larotrectinib can be prescribed regardless of tumor localization. We compared changes in the transcriptional activity of genes in brain tumors (BT) and thyroid cancer (TC) with rearrangement (NTRK+) and without rearrangement (NTRK-) of the NTRK genes using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. We revealed an increase in the transcription of the JUN gene in NTRK+ samples in comparison with NTRK- samples: by 1.6 times for BT (p=0.239) and by 2.5 times for TC (p=0.003). The transcription of eight HOX genes in NTRK+ BT samples was also increased (by 85-725 times, p<0.05) in comparison with NTRK-. In NTRK+ TC samples, the level of miR-31 and miR-542 was statistically significantly higher (by 3 and 2.5 times, respectively) than in NTRK-samples. For the NTRK+ BT samples, the levels of miR-10b, miR-182, and miR-21 more than 5-fold surpassed the corresponding values in NTRK-samples (p<0.05). These findings reflect differences in activation of gene transcription resulting from NTRK gene rearrangement in BT and TC.

Clinical Significance of CD66b Expression in Non-Small Cell Lung Cancer.

We studied the expression of CD66b (a protein of the cancer-embryonic antigen family, expressed mainly in neutrophils) in tumor and stromal cells of non-small cell lung cancer (93 samples). The number of CD66b+ neutrophils is not associated with clinical and morphological parameters of the tumors and the disease prognosis. However, CD66b is expressed in the tumor cells of most studied samples. CD66b expression is also associated with the histological type of tumor and its localization. Increased expression of CD66b in tumor cells indicated a more favorable prognosis, which allows using this protein as a prognostic marker and as a potential target for the immunotherapy.

Long Non-Coding RNAs and microRNAs Groups in the Regulation of Expression Level of a Number of Tumor-Associated Genes in Ovarian Cancer.

The search for interacting long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and mRNAs of protein-coding genes through the mechanism of competing endogenous RNAs in tumors of ovarian cancer patients was carried out. The levels of expression of 24 lncRNAs, 20 miRNAs, and 28 mRNAs of protein-coding genes involved in oncogenesis were determined by real-time PCR on a set of representative samples. Correlations between lncRNAs/miRNA and miRNA/mRNA levels in ovarian cancer samples were analyzed. We identified 8 pairs of lncRNAs/miRNA and 17 pairs of miRNA/mRNA, the expression levels of which have a negative correlation. Five triplets of potentially interacting lncRNAs/miRNA/mRNA have been identified, among which the most significant triplet is the OIP5-AS1/miR-203a-3p/ZEB1. The data obtained determine new epigenetic profiles, as well as new potential biomarkers and targets for targeted therapy of ovarian cancer patients.

Biochemical profile of Bence-Jones type multiple myeloma.

Multiple myeloma (MM) is a malignant tumor occurring from plasma cells that produce an abnormal monoclonal immunoglobulin - a paraprotein. A distinctive feature of Bence-Jones myeloma is the excretion of monoclonal free light chains of immunoglobulins with 24h urine, and the absence of monoclonal intact immunoglobulins secretion. Comprehensive analysis of biochemical parameters in blood serum and 24h urine in patients with Bence-Jones multiple myeloma using electrophoretic and immunoturbidimetric methods to assess their sensitivity as biomarkers. 50 patients with a morphologically confirmed diagnosis of MM of the Bence-Jones immunochemical type were examined. 28 people without oncological diseases were examinedas a control. Detection of monoclonal secretion in blood serum and daily urine was performed by immunofixation electrophoresis on the Hydrasys 2 electrophoretic system (Sebia). The determination of free light chains of immunoglobulins (FLC) was performed by the immunoturbidimetric method (Binding Site) on an Advia 1800 analyzer (Siemens). Analysis of IgG, IgA, IgM, ß2-microglobulin and C-reactive protein was performed on Cobas 6000 analyzer (Roche). The median excretion of Bence-Jones protein in 24h urine of MM patients was 0.49 g/24h (0.06-2.45 g/24h). In the blood serum, in 86% of cases, the presence of paraproteinemia, represented by κ and λ type light chains of immunogloublins was detected. At the same time, the frequency of detection of monoclonal secretion in blood serum in Bence-Jones type λ myeloma was 95.7%, which was statistically significantly higher than the frequency of detection of monoclonal secretion of type κ - 77.8%. In patients with identified paraproteinemia, Bence-Jones protein excretion in daily urine (median 0.82 g/day) was statistically significantly higher than in patients without a monoclonal component detected in blood serum (median 0.04 g/24h). The levels of FLC in blood serum obtained by immunoturbidimetry in Bence-Jones myeloma of the corresponding type were higher than the reference levels in 100% of cases. The median level of κ-FLC reached 4358 mg/l, λ-FLC - 2225 mg/l, which was statistically significantly higher than the control levels. The median concentrations of IgG, IgA and IgM in patients with Bence-Jones myeloma were statistically significantly lower than in the control group, while the medians of ß2-microglobulin and C-reactive protein were significantly higher than in the control. Our investigation showed high diagnostic efficiency of electrophoretic and immunoturbidimetric analysis of monoclonal secretion in patients with Bence-Jones MM, while FLC analysis demonstrated maximum sensitivity. Bence-Jones MM revealed biochemical signs of secondary immunodeficiency and general inflammatory syndrome.

Chromogranin B in blood serum of patients with neuroendocrine tumors.

Neuroendocrine tumors (NETs) are a heterogeneous group of neoplasms from cells of the diffuse neuroendocrine system. Chromogranin B (CgB) is an acidic protein of the granin family, which can be used to detect the tumours of neuroendocrine nature. Analysis of levels and evaluation of the diagnostic efficiency of CgB in the blood serum of patients with NETs of various localizations. Patients with NETs (n=121) without specific treatment were examined. In the study were presented next localizations: 74 - pancreas, 20 - stomach, 12 - large intestine, 15 - other localizations (lungs, mammary gland, prostate gland, NETs with unidentified primary). 54 practically healthy donors were examined as control group. The determination of CgB in blood serum was performed with ELISA method on BEP 2000 analyzer using a standardized test system Human Chromogranin B (USCN, China). CgB levels in common NET group (median 18.9 ng/mL) were statistically significantly higher than in the control group (8.8 ng/mL). The highest median was obtained in group of intestinal NETs (21.2 ng/ml), which exceeded the median of the control group by more than 2.4 times. According to ROC analysis in the common NET group relative to the control group, the area under the curve AUC was 0.88 (95% CI 0.83-0.929). According to cut-off level of CgB - 15.8 ng/ml, the diagnostic sensitivity was 69.4%, with a specificity of 96.3%. The highest diagnostic sensitivity was in the group of the intestinal NETs (75.0%) and pancreas (71.2%). The study showed the significance of CgB as a potential biochemical marker of NETs with various localizations, alternative to CgA.

Diagnostic and prognostic potential of the resident non-small cell lung cancer microbiome.

The data of a comprehensive comparative study of the taxonomic composition of the resident microbiome of tumors from 26 patients with non-small cell lung cancer are presented. Analysis of taxonomic diversity revealed 10 types, 280 genera and 788 species of microorganisms. The analysis of the relative content and prognostic significance was carried out for 62 dominant genera. Differences in the relative abundance of bacteria of the genera Acinetobacter, Halomonas, and Chryseobacterium between tumor and conditionally normal lung tissue were found, but their diagnostic potential was not confirmed. The correlation analysis did not reveal any relationship between the content of various genera of bacteria and the histological type of the tumor, its localization, and the age of the patients. Differences were found in the content of the studied bacteria depending on the stage of the disease, the presence of regional metastases and tumor differentiation. The prognostic significance of bacteria of the genera Variovorax and Pseudoclavibacter in non-small cell lung cancer was established. The results obtained can be used in the development of new effective methods for the diagnosis and prognosis of non-small cell lung cancer.

Blood Serum Zonulin in Colorectal Cancer, Autoimmune Bowel Diseases, and Irritable Bowel Syndrome.

Zonulin content in blood serum of patients with colorectal cancer (CRC; n=152; 30-84 years) and patients with large bowel adenomas (n=32; 39-82 years) was measured by standardized kit IDK Zonulin ELISA (Immundiagnostik AG). The healthy control group (n=50) comprised volunteers (27 women, 23 men; 25-68 years); pathological control group (n=84) - patients (55 women, 29 men;18-84 years) with irritable bowel syndrome (n=29), Crohn's disease (n=5), and ulcero-necrotic colitis (n=50). In comparison to healthy control group, the level of zonulin was significantly increased in CRC patients (p<0.0000001) and in patients with benign large bowel tumors (p<0.004), as well as in patients with inflammatory intestine diseases and with irritable bowel syndrome (p<0.0002). Zonulin level in blood serum of CRC patients was slightly, but significantly higher (p<0.05) than in the group of pathological control. ROC curve construction revealed that at optimal zonulin cut-off level (52.2 ng/ml), the diagnostic sensitivity of CRC detection was 66.7% and specificity relative to healthy control was 81.8%. The specificity relative to the combined control group (healthy control+non-tumor bowel diseases) was only 68.9%. Thus, no acceptable cut-off levels for differentiation between malignant and benign tumors, as well as between tumor and non-tumor large bowel pathologies were found. Analysis of the associations between serum zonulin level and the main clinical and pathological characteristics of CRC demonstrated that the level of this marker increased with disease progression (p<0.01; Kruskal-Wallis test), but was not associated with individual criteria of the TNM system, tumor localization, histological structure, and malignancy grade.

Search for New Target Genes of MicroRNA for Differential Diagnosis of Benign and Malignant Neoplasms of the Thyroid Gland by In Silico Methods.

Differential diagnosis of thyroid gland neoplasms is an urgent problem in modern oncothyroidology. This is especially true for the diagnosis of follicular thyroid cancer and follicular thyroid adenoma at the preoperative stage. In this study, in silico methods were used to search for potential markers that are microRNA target genes. A list of 19 microRNAs was compiled, the expression of which varies depending on the type of thyroid neoplasms. For these microRNAs, the target genes were selected considering tissue specificity and association with thyroid diseases. We selected 9 target genes (MCM2, RASSF2, SPAG9, SSTR2, TP53BP1, INPP4B, CCDC80, GNAS, and PLK1), which can be considered as promising markers according to published data. Also, 6 new potential markers (CDK4, FGFR1, ERBB3, EGR1, MYLK, and SRC) were found, which make it possible to distinguish between follicular thyroid cancer and follicular thyroid adenoma. The proposed algorithm using various bioinformatics tools allows us to identify potential markers for the differential diagnosis of thyroid neoplasms.

Prediction of EVT6-NTRK3-Dependent Papillary Thyroid Cancer Using Minor Expression Profile.

Solid tumors resulting from oncogenic stimulation of neurotrophin receptors (TRK) by chimeric proteins are a group of rare tumors of various localization that respond to therapy with targeted drugs entrectinib and larotrectinib. The standard method for detecting chimeric TRK genes in tumor samples today is considered to be next generation sequencing with the determination of the prime structure of the chimeric transcripts. We hypothesized that expression of the chimeric tyrosine kinase proteins in tumors can determine the specific transcriptomic profile of tumor cells. We detected differentially expressed genes allowing distinguishing between TRK-dependent tumors papillary thyroid cancer (TC) from other molecular variants of tumors of this type. Using PCR with reverse transcription (RT-PCR), we identified 7 samples of papillary TC carrying a EVT6-NTRK3 rearrangement (7/215, 3.26%). Using machine learning and the data extracted from TCGA, we developed of a recognition function for predicting the presence of rearrangement in NTRK genes based on the expression of 10 key genes: AUTS2, DTNA, ERBB4, HDAC1, IGF1, KDR, NTRK1, PASK, PPP2R5B, and PRSS1. The recognition function was used to analyze the expression data of the above genes in 7 TRK-dependent and 10 TRK-independent thyroid tumors obtained by RT-PCR. On the test samples from TCGA, the sensitivity was 72.7%, the specificity - 99.6%. On our independent validation samples tested by RT-PCR, sensitivity was 100%, specificity - 70%. We proposed an mRNA profile of ten genes that can classify TC in relation to the presence of driver NTRK-chimeric TRK genes with acceptable sensitivity and specificity.

Development of a Test System to Detect the Omicron Variant of SARS-CoV-2 and the Frequency of Its Detection in Patients.

We developed a new test system to detect the omicron variant of SARS-CoV-2 using allele-specific reverse transcription PCR and estimated the frequency of its detection in patients living in the Novosibirsk Region. Clinical samples were divided into 3 groups: samples collected from December 1 to December 30, 2021 (group 1; n=66), from December 30, 2021 to January 10, 2022 (group 2; n=20), and from January 11 to January 22, 2022 (group 3; n=101). Based on the identification of 5 mutations specific to SARS-CoV-2 (B.1.1.529), two systems of oligonucleotide primers and probes were developed for detecting this coronavirus genotype in clinical samples. Limit of detection (LOD95) was 4×103 genome equivalents per 1 ml of clinical sample for the first test system and 2×103 for the for the second test system. The omicron variant of SARS-CoV-2 was absent in group 1 of studied samples, but was detected in 20% (4/20) of group 2 samples and 88% of group 2 samples collected within less than 2 weeks of January 2022. Using developed test system, we showed that in less than 2 weeks the omicron variant has become dominant in patients, which confirms previously published data on its exceptional contagiousness.

The Level of LINE-1 mRNA Is Increased in Extracellular Circulating Plasma RNA in Patients with Colorectal Cancer.

We performed a comparative quantitative analysis of LINE-1 mRNA levels in extracellular total plasma RNA in patients with colon cancer and practically healthy donors. Quantitative multiplex PCR with reverse transcription was used to assess the level of LINE-1 and 18S rRNA mRNA in extracellular total plasma RNA. The median of LINE-1 mRNA values in colon cancer patients (4.95) was significantly higher than in healthy donors (2.3) (p=0.037). It was shown for the first time that the level of LINE-1 mRNA in total RNA from blood plasma can be determined in the format of a liquid biopsy and serve as a new potential non-invasive marker of colon cancer.

Pro-Gastrin-Releasing Peptide as a Marker of Small Cell Lung Cancer.

The serum levels of pro-gastrin-releasing peptide (proGRP), neuron-specific enolase (NSE), and chromogranin A (CgA) were studied in 69 patients with small cell lung cancer and 50 apparently healthy donors. A significant increase of all studied biochemical markers was revealed in small cell lung cancer patients, while the highest diagnostic efficiency was demonstrated by proGRP compared to NSE and CgA. ProGRP is a promising biochemical marker of small cell lung cancer, especially sensitive in patients with distant metastases (in the brain, liver, and bones).

The Role of Long Non-Coding RNA CCAT1 and SNHG14 in Activation of Some Protein-Coding Genes Associated with the Development of Ovarian Cancer.

Late diagnosis of ovarian cancer is one of the most important problems in its treatment. Long non-coding RNA (lncRNA) are a poorly studied, but promising type of diagnostic biomarkers. We studied the lncRNA interactome to identify biomarkers with potential significance for molecular diagnostics of ovarian cancer. By screening the TCGA database, we identified differentially expressed lncRNA CCAT1 and SNHG14. Based on the indices of complementarity of CCAT1 and SNHG14 to the mRNA sequences, we selected 5 protein-coding genes MAPK1, c-MET, TGFB2, SNAIL1, and WNT4 associated with the epithelial-mesenchymal transition. Real-time PCR on 54 ovarian cancer samples confirmed the high expression levels of CCAT1 and SNHG14 (logFC>1.5, p<0.05). A positive correlation between the expression levels of two lncRNA and mRNA of 5 genes in 6 pairs was established. The activating effect of CCAT1 and SNHG14 on the expression of these genes can be mediated by miR-203 and miR-124.

Assessment of iron metabolism disorders and adequate treatment of anemic syndrome in patients with breast cancer on the background of adjuvant chemotherapy.

Early and adequate correction of the anemic syndrome (AS) of cancer patients can prevent deterioration in the quality of life and be considered as a reserve for increasing the effectiveness of treatment for breast cancer (BC). The aim of the study was to assess the status of iron using modern methods of ferrokinetics in breast cancer patients on the background of adjuvant chemotherapy for early diagnosis and adequate treatment of AS. The object of the study included 21 breast cancer patients with a relatively favorable prognosis, with luminal types A and B (Her 2 / neu positive or negative), three times negative type. The examination was carried out in the postoperative period, against the background of adjuvant chemotherapy. The main metabolites of ferrokinetics were studied: hepcidin 25 (GP25); ferritin (FR); soluble transferrin receptors (rRTP); transferin (TRF); iron (Fe); erythropoietin (EPO); CRP and IL-6 indicators. AC correction was performed (ferinject, epotin-alpha, B12). 10 (47.6%) patients with breast cancer had AS. Most of them were diagnosed with IDA with microcytic, hypochromic characteristics of erythrocytes, low concentration of FR, Fe, GP25, IL-6, CRP, and high levels of TRP and rRTP. Functional iron deficiency (FDF) was established in some patients. In contrast to patients with IDA, they had a high concentration of FR, CRP and significant production of GP25, IL-6. The EPO level was not optimal for the majority of patients with AS. In isolated cases, during treatment with recombinant erythropoietins, a deficiency of vitamin B12 (cyanocobalamin) was revealed. The rational use of iron preparations, vitamins, and recombinant forms of EPO made it possible to restore Fe metabolism, stabilize the hemoglobin level, and also improve the condition of most breast cancer patients. The obtained data on IL-6, GP25, CRP indicate a certain relationship between them in the development of anemia with VDF in breast cancer patients and the need for further study of the characteristics of iron metabolism in cancer patients.