Radiobiological Effects of Intra Operative Radiotherapy

دوازدهمين كنگره بين المللي سرطان پستان

4 الي 6 اسفند 1395، تهران - ايران

Presentation Type: Speech
Abstract: Breast cancer is the most common cause of malignant disease in women worldwide. During One decade local therapeutic strategies have changed from radical surgery, i.e. Mastectomy of The involved breast, to a multimodality treatment, consisting of breast conserving surgery, Followed by whole breast irradiation. Pathological analyses revealed that the greatest subclinical tumor cell density (90%) is confined to an area of 4 cm surrounding the macroscopic tumor border. Therefore, the tumor bed itself represents a region with the highest probability of local tumor recurrences in a dimension of about 65-80% of all events. In respect to the fact that the probability of tumor control is a directly exponential function of the applied dose, retrospective clinical trials showed a lower local recurrence rate if the dose is escalated by adding a `Boost`, defined as a limited irradiation to the former tumor bed. By these experimental approaches, we tried to answer two clinical/biological questions: First, first, does intraoperative radiotherapy have an immediate effect on the local tumor? Second what is the effect of intraoperative radiotherapy after 24 hours? For answering these 2 main questions we used 2 newest techniques in biology: next generation sequencing for genome study and Quantification of proteins by iTRAQ. Breast tumor (T), margin of tumor before IORT (MB), margin of tumor immediately after IORT (MAi) and margin of tumor 24 hours after IORT (MA24h) tissues were collected by the surgeons from the Khatam Hospital. The obtained surgical specimens were immediately placed in liquid nitrogen, and transferred to laboratory for RNA and protein extraction by Trizol protocol. RNA was quantified by using Nanodrop1 and the Agilent 2100 Bioanalyzer. Then, 1 µg of total RNA was used for rRNA depletion using RiboZero (Illumina) and stranded RNA-seq libraries were constructed using a TruSeq Stranded Total RNA Library Prep Kit (Illumina,). Then 2×100 paired-end sequencing was performed on an Illumina HiSeq 2500 (Illumina) at the Science for Life Laboratory. The insert sized ranged from approximately 50 to 300 bp. Protein was quantified by using Bradford quantitative method and sample integrity detected by polyacrylamide gel electrophoresis. The applications of these technologies is data preprocessing, differential gene expression analysis, alternative splicing analysis, variants detection and allele-specific expression, pathway analysis, co-expression network analysis, and applications combining various experimental procedures beyond the achievements that have been made.We use RNA-Seq and iTRAQ technologies for differential gene and protein expression analysis between samples before and after of IORT. Genes and protein interest in this study are: intrinsic pathway of apoptosis, extrinsic pathway of apoptosis, related to necrosis, Genes and protein related to angiogenesis, Genes related to EMT, Genes related to tumor suppressor, Oncogenes, Genes related to inflammation initiation, Genes related to HLA antigens, Genes related to stimulation of cytokine and chemokine production, Genes related to inflammation receptors, Genes and protein related to tumor metastasis, Genes and protein related to cell invasion, Genes and protein related to radiotherapy resistance.