الفهرس 
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Abstract
Breast cancer is considered to be the most common type of malignancy in the female population, with about 2.3 million cases that accounts for 11.7% of newly diagnosed cancers.
Risk factors that lead to the disease can be non- modifiable factors such as old age, family history, female gender, certain races as Caucasians and genetic predisposition or modifiable factors as exposure to high level of estrogens and high-fat diet, obesity and breast feeding.
The burden of breast cancer patients is increasing. According to GLOBOCAN statistics in 2018 approximately 2.1 million women were diagnosed with breast cancer in that year, with 626,679 related deaths. According to the results of the National Population-Based Cancer Registry Program of Egypt, breast cancer represents 32% of all malignancies among females.
Genome-wide transcriptome studies have revealed that there exist a large number of non-coding ribonucleic acids (ncRNAs) with larger and more diverse role in biological processes than initially anticipated.
LncRNAs are mainly transcribed by RNA polymerase II (RNA PII) and are polyadenylated, spliced, and mostly localized in the nucleus.
They are viewed as fundamental regulators of transcription. Many lncRNAs have been characterized and several models of action have been proposed. LncRNAs are seen to be involved in gene regulation at the transcriptional level by functioning as signal, guide, decoy, or scaffold RNAs.
Several lncRNAs function as the structural scaffolds of membraneless subnuclear structures or nuclear bodies. Nuclear Enriched Abundant Transcript (NEAT-1) is a lncRNA that acts as an important architectural component of paraspeckle nuclear bodies.
Thus, the need to study the expression of lncRNA NEAT1 in breast cancer patients is important and crucial.
The present study aimed to evaluate the pattern of relative expression of long non-coding-RNA NEAT1 in breast cancer patients and its correlation with clinico-pathological criteria.
The study included 50 females having BC, where 58% of cases were above 50 years while 42% below 50 with a mean of 54 years, in which 80% of the cases were postmenopausal. 62% of BC cases showing no family history for breast cancer. 84% of the BC cases were multipara, 6% were nullipara while 10% have one child. 90% of the cases gave history of natural breastfeeding while only 10% were non lactating.
According to histopathological grading, 2 cases (4%) were grade 1, 39 cases (78%) were grade 2 and 9 cases (18%) were grade 3. 44% of the cases had left side breast cancer from which 18 cases had left modified radical mastectomy (MRM) and 4 cases had left conservative surgery, while 56% of the cases had right side breast cancer from which 26 cases had right MRM and only 2 cases had right conservative surgery.
According to hormonal profile, all cases were ER and PR positive. HER2 receptor was positive in 9 cases (18%) and negative in 41 cases (82%).29 patients had a molecular subtype luminal A, while 12 patients had a molecular subtype luminal B (HER 2 Negative) and 9 patients had a molecular subtype luminal B (HER2 Positive).
A statistically significant difference between breast cancer tissue and normal tissue was found regarding relative tissue expression level of NEAT-1 (p value of 0.027). There was no statistically significant difference in tissue NEAT-1 expression level among the studied variables: age, parity, lactation history, type of surgery, tumor grade, menopausal status, histopathological type, tumor size, lymph node metastasis, staging, HER2 receptors as well as molecular subtypes.
A receiver operating characteristics (ROC) curve analysis for NEAT-1 tissue expression level was done to differentiate between normal and tumor tissue. It showed an area under the curve (AUC) of 0.572. A cut-off value for the NEAT-1 tissue level of 1.44 was generated to discriminate between normal and tumor tissue, resulting in a diagnostic sensitivity of 50%, specificity of 90%, positive (PPV) and negative (NPV) predictive values of 83.3% and 64.3 %.