الفهرس 
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Abstract
Breast cancer (BC) is the most common cancer in the female population, representing a major health-care challenge especially in developing countries as Egypt necessitating the development of new approaches that may facilitate better diagnosis and more effective treatment.
Elevated levels of circulating cell-free DNA (cfDNA) have been detected in diseases of different origins, such as trauma, stroke, burns, sepsis, autoimmune diseases, and also cancer. Several approaches have been used to measure cfDNA in plasma and serum, including non-coding DNA like repetitive ALU sequences. These repetitive DNA sequences are known to be distributed everywhere in the genome, with approximately 1.4 million copies per genome for the ALUs.
Two ALU fragments with 115 and 247 base pairs (bp) were measured and then DNA integrity is calculated as a ratio of ALU-247 to ALU-115. The shorter ALU-115 should represent the total amount of DNA (Apoptotic and necrotic), while the longer ALU-247 fragments are considered as necrotic products.
CA 15-3 is the protein product of the MUC1 gene and it is the most widely used serum marker in breast cancer.
The aim of this study was to investigate the possible role of plasma circulating cfDNA (ALU-247 and ALU-115) and DNA integrity as a diagnostic and prognostic marker of breast cancer as compared to plasma CA 15.3. In addition to correlation of ALU-247, ALU-115 and DNA integrity and CA 15.3 with clinicopathological characteristics.
The present study was carried out on 50 females. 40 females with breast cancer of different clinical stages, and 10 normal healthy females were considered as a control group. Blood samples were withdrawal from all patients before surgery and from control subjects. The plasma samples were kept frozen at – 80oC until used for quantification of cell-free circulating DNA by real time PCR and CA 15.3 by ELISA kit.
Our study revealed that, the mean values of plasma ALU-247, ALU-115 as well as DNA integrity were significantly higher in breast cancer patients as compared to control groups.This may be attribute to the following different hypotheses including: active libration by the tumor itself, connection to the events of necrosis, apoptosis, autophagia, rupture of tumor cells and circulation of micrometastases.
from this study, ALU-247, ALU-115 and DNA integrity showed a trend that increased with breast cancer stages and this may be due to the DNA released from malignant tumors into the blood stream is enhanced by lymph vascular invasion (LVI) because direct lymphatic or blood flow through the tumors enables dissemination of viable tumor cells and enhances diffusion of DNA released from dead tumor cells into the bloodstream.
CA 15.3 level in breast cancer patients as well as in each stage of breast cancer was significantly increased. This may be due to the overexpression of gene MUC1 which encoded CA 15.3 and may be related to tumor burden or implied the presence of malignant disease.
Our results showed a relation between circulating cfDNA (ALU-247 and ALU-115) and stage as well as metastasis at the beginning of the study. Suggesting that tumour-derived DNA could be transferred from one cell to another via the phagocytosis of apoptotic bodies and is stable over time, suggesting that tumour-derived DNA plays a possible role in the development of metastasis
In this study DNA integrity was correlated to HER2 and breast cancer stage. The amplification of HER2 can serve as a predictive factor in breast cancer. So this correlation may be attributed to potentiation of tumor cell motility, protease secretion and invasion, and also modulation of cell-cycle checkpoint function, DNA repair, and apoptotic responses.
CA 15.3 was associated with tumor size, stage as well as metastasis at the beginning of the study. This is logical, since it is considered that tumor marker reflects the number of malignant cells as well as their access to the circulation.
By ROC curve analysis, it found that the values of plasma ALU-247, ALU-115, DNA integrity and plasma CA 15.3 were diagnostic markers. CA 15.3 was superior to DNA integrity followed by ALU-247 and ALU-115 for prediction of breast cancer patients.
Another ROC curve analysis was used to evaluate the prognostic performance of plasma ALU-247, ALU-115, DNA integrity and plasma CA 15.3 before surgery to predict metastasis. The present study revealed that both plasma ALU-247 and ALU-115 are good in identifying patients who developed metastasis from those didn’t have metastasis in breast cancer.
No statistically significant difference in DFS and OS were found between patients with elevated levels plasma ALU-247, ALU-115, DNA integrity and plasma CA 15.3 with those of lower levels by means of log-rank test (Kaplan-Meier curves).
from the study we conclude that:
1- Plasma ALU-247, ALU-115, DNA integrity and plasma CA 15.3 are diagnostic marker for breast cancer, and CA 15.3 was superior to DNA integrity followed by ALU-247 and ALU-115.
2- Both ALU-247 and ALU-115 is seemed to be a preoperative prognostic markers for breast cancer.
Recommendations:
Further studies are recommended by using large number of samples and long follow-up duration to indicate:
1. The definite prognostic effect of DNA integrity and CA 15.3 preoperatively.
2- The correlation of cfDNA, DNA integrity and CA 15.3 with DFS and OS in breast cancer patients.