Caffeic Acid Phenethyl Ester Increases Radiosensitivity of Estrogen Receptor-Positive and -Negative Breast Cancer Cells by Prolonging Radiation-Induced DNA Damage / 한국유방암학회지

PURPOSE: Breast cancer is an important cause of death among women. The development of radioresistance in breast cancer leads to recurrence after radiotherapy. Caffeic acid phenethyl ester (CAPE), a polyphenolic compound of honeybee propolis, is known to have anticancer properties. In this study, we examined whether CAPE enhanced the radiation sensitivity of MDA-MB-231 (estrogen receptor-negative) and T47D (estrogen receptor-positive) cell lines. METHODS: The cytotoxic effect of CAPE on MDA-MB-231 and T47D breast cancer cells was evaluated by performing an 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. To assess clonogenic ability, MDA-MB-231 and T47D cells were treated with CAPE (1 µM) for 72 hours before irradiation, and then, a colony assay was performed. A comet assay was used to determine the number of DNA strand breaks at four different times. RESULTS: CAPE decreased the viability of both cell lines in a dose- and time-dependent manner. In the clonogenic assay, pretreatment of cells with CAPE before irradiation significantly reduced the surviving fraction of MDA-MB-231 cells at doses of 6 and 8 Gy. A reduction in the surviving fraction of T47D cells was observed relative to MDA-MB-231 at lower doses of radiation. Additionally, CAPE maintained radiation-induced DNA damage in T47D cells for a longer period than in MDA-MB-231 cells. CONCLUSION: Our results indicate that CAPE impairs DNA damage repair immediately after irradiation. The induction of radiosensitivity by CAPE in radioresistant breast cancer cells may be caused by prolonged DNA damage.

High-dose-rate 192Ir brachytherapy dose verification: a phantom study

The high-dose-rate [HDR] brachytherapy might be an effective tool for palliation of dysphagia. Because of some concerns about adverse effects due to absorbed radiation dose, it is important to estimate absorbed dose in risky organs during this treatment. This study aimed to measure the absorbed dose in the parotid, thyroid, and submandibular gland, eye, trachea, spinal cord, and manubrium of sternum in brachytherapy in an anthropomorphic phantom. To measure radiation dose, eye, parotid, thyroid, and submandibular gland, spine, and sternum, an anthropomorphic phantom was considered with applicators to set thermoluminescence dosimeters [TLDs]. A specific target volume of about 23 cm3 in the upper thoracic esophagus was considered as target, and phantom planned computed tomography [CT] for HDR brachytherapy, then with a micro-Selectron HDR [192Ir] remote after-loading unit. Absorbed doses were measured with calibrated TLDs and were expressed in centi-Gray [cGy]. In regions far from target [>/= 16 cm] such as submandibular, parotid and thyroid glands, mean measured dose ranged from 1.65 to 5.5 cGy. In closer regions [

Evaluation of organs at risk's dose in external radiotherapy of brain tumors

Radiotherapy plays an important role in the management of most malignant and many benign primary central nervous system [CNS] tumors. Radiotherapy affects both tumor cells and uninvolved normal cells; so, it is important to estimate absorbed dose to organs at risk in this kind of treatment. The aim of this study was to determine the absorbed dose to chiasma, lens, optic nerve, retina, parotid, thyroid and submandibular gland in frontal lobe brain tumors radiotherapy based on treatment planning system [TPS] calculation and direct measurement on the phantom. A head and neck phantom was constructed using natural human bone and combination of paraffin wax and Sodium Chloride [NaCl] as tissue-equivalent material. Six cylinders were made of phantom material which had cavities to insert Thermoluminescent Dosimeters [TLDs] at several depths in order to measure absorbed dose to chiasma, lens, optic nerve, retina, parotid, thyroid and submandibular gland. Three routine conventional plans associated with tumors of this region and a new purposed technique were performed on the phantom and dose distribution and absorbed dose to critical organs were compared using treatment planning system [TPS] calculation and direct measurement on the phantom. Absorbed doses were measured with calibrated TLDs and are expressed in centigray [cGy]. In all techniques absorbed dose to all organs except the lenses were at their tolerance dose levels and in the new purposed technique, absorbed dose to chiasma was significantly reduced. Our findings showed differences in the range of 1-5% in all techniques between TPS calculation and direct measurements for all organs except submandibular glands and thyroid. Because submandibular glands and thyroid are far from primary radiation field, TLD reading in these regions although small but differs from TPS calculation which shows very smaller doses. This might be due to scattered radiation which is not well considered in the TPS. In the new technique, because the chiasma is out of the radiation field, absorbed dose was reduced significantly

Dosimetry of Esophageal radiotherapy: a phantom study

Esophageal cancer is the eighth most ordinary cancer and the sixth most common cancer between the males and ninth for females in the world; its major and effective treatment is external radiotherapy. This type of cancer can be found in different areas of esophagus including cervical, upper, middle and lower esophagus. In this treatment, healthy tissues such as the trachea, spine and sternum and even thyroid receive dose and it is important that the absorbed doses by these organs be in their tolerance dose levels. We measured the surface and depth doses in an anthropomorphic phantom using thermoluminescent dosimeters. To do so, a target volume was considered in the phantom as a primary esophageal tumor with margins of 5 cm in the distal and proximal, and 3 cm in lateral. Phantom was CT planned and treatment was performed according to patient treatment. The considered measurement locations were Eye, right and left Parotid, left and right Submandibular, left and right Thyroid, Trachea, Manubrium of Sternum and Spine. Our results show that in places located further to primary beam such as Thyroid [phase one], Trachea, Spine and Sternum, the difference between dose from TPS and TLD measurements is observed. In organs which have placed within scattered radiation, the difference is insignificant [P-value>/=0.05], although some differences might cause by TLD limitations. In conclusion, the TPS calculated and TL measured doses distinguish significantly at the spine [depth], trachea [depth] and manubrium of sternum especially in phase 1 which might be due to the calculation algorithm used by the planning system which is reliable in homogeneous medium, but TL measurements were performed in the heterogeneous anthropomorphic phantom