LINE-1 METHYLATION IN BLOOD AND TISSUES OF PATIENTS WITH BREAST CANCER.

Methylation is an epigenetic alteration proved to be involved in many disease processes including cancer. This change affects mainly gene promoters and repetitive sequences in genome. Long Interspersed Nuclear Element-1 (LINE-1) is a family of retrotransposons - repetitive elements that modify gene activity and can themselves be targeted by epigenetic mechanisms. LINE-1 methylation level is a surrogate marker for global methylation. In many conditions this parameter is found to be altered not only in affected cell groups, but also throughout other tissues. The aim of our study was to compare LINE-1 methylation pattern in DNA extracted from blood of the patients with benign and malignant breast tissue. In addition, we investigated correlation of LINE-1 methylation in blood and tissues of same patients and relationship of all variables with histopathologic and phenotypic characteristics of tumors. Patients with biopsy-proved ductal invasive carcinoma of breast and no preoperative chemo/radiotherapy were chosen for the study group. Another pool of patients with various benign breast lesions represented controls. Blood samples from both group members were collected preoperatively. Tumor tissue sections were processed for pathology report and part of remaining tissue was used for methylation study. LINE-1 methylation level was quantified using ELISA-based assay. It was analyzed in combination with histologic and phenotypic tumor parameters and compared between different tissues and different study groups. LINE-1 was found to be significantly hypomethylated in breast cancer tissue compared to blood. Blood samples of patients with malignant tumors showed slightly lower methylation level, than samples obtained from control group members. Lymphovascular invasion was the only aggressiveness-determining factor that was found to be at least weakly correlated with LINE-1 hypomethylation in blood. We can conclude, that global hypomethylation measured by LINE-1 methylation level is significant in tumor tissue. But there is no significant difference between LINE-1 methylation levels in blood of patients with benign and malignant breast tumors; therefor LINE-1 hypomethylation in blood cannot be used as a marker for early tumor detection. Neither is it valid for determination of tumor behavior.

ONCOPLASTIC SURGERY OF MULTICENTRIC (MULTIFOCAL) BREAST CANCER (CASE REPORT).

The multicentric/multifocal form of breast cancer has been considered as relative contraindicationfor breast conserving surgery. According to the results of the studies conducted in the last century, the local recurrence rate of the disease after breast conserving surgeries of multicentric/multifocal breast cancer exceeds 40%. Thus these data were considered as main argument for mastectomy advocates, as non-alternative surgical treatment in these cases. Wide clinical application of oncoplastic surgical techniques gave us possibilities to resolve dilemma: excise tumor - containing quadrant with achieving clear margins and satisfactory cosmetic outcome, without increasing risk of disease-related complications. In cases of multicentricity/ multicocality of breast cancer, total axillary lymphadenectomy might be avoided when size of tumor is less than 2 cm and there are no signs of malignant involvement of axillary lymph nodes; In case of clinically negative axillary lymph nodes - sentinel lymph node biopsy might be the standard option. Of course, adjuvant treatment should be planned in accordance with the principles of personalized medicine, based on the results of multidisciplinary review and taking into consideration modern advanced guidelines and recommendations.

[Efficiency of lymphatic mapping by intradermal injection of vital blue dye for sentinel node identification in T1-2 N0-1 M0 stage breast cancer patients].

The lymphatic mapping and sentinel lymphadenectomy procedure is a highly accurate method of axillary staging in breast cancer. Because no other method accurately predicts axillary node status without complete axillary dissection, this technique has a potential to become the standard method of axillary staging for breast cancer in near future. The aim of the study was to evaluate efficiency of lymphatic mapping by intradermal injection of vital blue dye for sentinel node identification in T(1-2) N(0-1) M(0) stage breast cancer patients. The sentinel lymph node biopsy with total axillary dissection was performed in 36 patients. The efficiency of lymphatic mapping by intradermal injection of vital blue dye (identification rate) was 97,2%, specificity--100% and the false-negative rate was 2,8%.

[Sentinel nodes identification efficacy prognostic criteria in breast cancer].

The sentinel node concept assumes that a malignancy that metastasizes by the lymphatic route will initially travel to one or a few lymph node(s). Although a tumor may disseminate to other nodes, it will remain in the sentinel node, and therefore the status of the entire basin is predicted by the sentinel node. The sentinel lymph node biopsy with total axillary dissection was performed on 99 patients. The identification rate was 69,7%, specificity 62,6%, and the false-negative rate was 7,1%. The impact of some prognostic factors on efficacy of visualization was also investigated. It was shown that the age of patients, stage of disease, localization of primary tumor, and method of injection of methylene blue were important prognostic factors for effective identification of sentinel lymph nodes in breast cancer patients.