Effect of different doses of radiation on morphogical, mechanical and chemical properties of primary and permanent teeth-an in vitro study.

BACKGROUND: Radiotherapy, applied to the head and neck region, can cause radiation side effects such as reduction of saliva and radiation caries. The aim of this study was to perform an in vitro assessment of the effects of radiation therapy on the morphological, mechanical, and chemical properties of primary and permanent teeth. METHODS: One hundred four extracted human teeth (52 impacted wisdom teeth, 52 primary molar teeth) were used. The teeth were divided into two parts in the mesiodistal direction. Of the 98 teeth, the vestibular sections were used for the vickers analysis and lingual sections were used for the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) analysis. The teeth in the experimental group were fixed to wax models. Each model had an equal number of teeth (n = 7). The doses were applied to the teeth for 6 weeks; 5 week days and 2Gy daily. After the radiotherapy was conducted weekly, a wax model was taken from radiation reception. Along with the elemental contents (Na, K, Mg, P, and Ca) of the teeth, enamel and dentin microhardness was evaluated, and SEM analyzes were performed on 6 teeth. RESULTS: Radiation caused a decrease in microhardness of enamel and dentin (p < 0.05). In the elemental analysis by ICP-OES, it was observed that there were decreases in all elements after 60Gy compared to the control group (p < 0.05). In the experimental groups, amorphous structures were encountered in SEM images. CONCLUSIONS: Radiation has negative effects on the teeth structure and additional studies are needed in this regard. This study indicates that radiotherapy patients are at a higher risk for dental caries.

The impact of the field width on VMAT plan quality and the assessment of half field method.

PURPOSE: The goal of this work is to investigate the field width dependence of the volumetric modulated arc therapy (VMAT) plan quality and to propose a half field method to irradiate large volumes effectively with VMAT. MATERIALS AND METHODS: We compared four different VMAT methods; namely three full field (3ff), four full field (4ff), three half field (3hf), four half field (4hf). To evaluate the impact of the field width on VMAT plan quality, 12 different size PTVs were created in the virtual phantom and treatment plans generated for each PTV were compared. The effectiveness of our half field method was tested using computed tomography (CT) data of 10 nasopharyngeal carcinoma patients. RESULTS: In the virtual phantom study, organs at risk (OAR) mean dose, the maximum point dose, and Homogeneity Index (HI) were found to be field width dependent. Conformation Number (CN) was not significantly affected. In the clinical study, 4hf plans obtained statistically significant dose reduction at brainstem (P < 0.001), right parotid (P = 0.034), oral cavity (P < 0.001), larynx (P = 0.003), cochlea (P = 0.017), lips (P = 0.024), and Body-PTV (P = 0.04) compared to 4ff plans. CONCLUSION: Our results indicate that VMAT plan quality is dependent on the field width. Half field VMAT method, with the help of reduced field width, shows a clear advantage for the irradiation of large size targets compared to traditionally used full field VMAT plans.

The Effect of Prognostic Factors and Adjuvant Radiotherapy on Survival in Patients with High-Grade Early-Stage Endometrial Cancer: A Retrospective Clinical Study.

BACKGROUND This retrospective clinical study aimed to investigate the effect of prognostic factors and adjuvant radiotherapy in patients with high-grade early-stage endometrial cancer on overall survival (OS) and disease-free survival (DFS). MATERIAL AND METHODS The medical records of patients diagnosed with high-grade, early stage (I or II) endometrial adenocarcinoma who had received adjuvant radiotherapy after surgery were reviewed. RESULTS Seventy-nine patients included 39 patients (49.4%) with stage II endometrial cancer, 25 patients (31.6%) with histologic grade 3 tumors, and 47 patients (59.5%) with endometrial cancer showing lymphovascular space invasion (LVSI). There were 45 patients (57.0%) who received external pelvic radiotherapy with an average dose of 46.0 Gy (range, 11.2-50.4 Gy), and 34 patients (43.0%) received vaginal brachytherapy (VBT) with an average dose of 21.5 Gy (range, 10-36 Gy). Multivariate analysis showed that tumor stage (HR, 4.066; 95% CI, 1.227-13.467; p=0.022) and histologic grade (HR, 16.652; 95% CI, 4.430-62.589; p<0.001) were independent predictors for OS. Increased serum CA-125 levels (HR, 1.136; 95% CI, 0.995-1.653; p=0.047) and histologic grade (HR, 3.236; 95% CI, 1.107-15.156; p=0.015) were independent predictors for DFS. Adjuvant radiotherapy was not found to be significantly associated with improved OS (HR, 1.259; 95% CI, 0.518-3.058; p=0.612) or DFS (HR, 1.056; 95% CI, 0.994-1.123; p=0.078). CONCLUSIONS This retrospective study showed that in high-grade early-stage endometrial cancer treated with postoperative adjuvant radiotherapy, independent predictors for OS were tumor stage and grade. Adjuvant radiotherapy was not associated with improved OS or DFS.

Postoperative Radiotherapy in Salivary Gland Carcinoma: A Single Institution Experience.

BACKGROUND: Salivary gland carcinoma are rare tumors and the main treatment is surgical. The addition of radiotherapy to surgery decreases locoregional relapses in high risk patients. Aim of our study is to retrospectively evaluate local control and survival and the factors affecting them in patients who received postoperative radiotherapy. MATERIALS AND METHODS: The medical records of 30 patients with salivary gland tumors operated on and referred to our clinic for adjuvant RT between January 2004 and June 2015 were retrospectively evaluated. RT was applied to the primary tumor or its lymphatics in a median dose of 60 Gy (48-66 Gy) in 1.8-2 Gy/fraction. The number of patients receiving concomitant chemotherapy was 8 (27%) and 22 (73%), respectively. RESULTS: The mean duration of follow-up was 47 months (range: 3-132 months). The mean duration between surgery and RT was 51 days and mean duration of RT was 43 days. Tumors were located in the parotid gland in 25 patients (83%), in the submandibular gland in four patients (14%), and in the sublingual gland in one patient (3%). Histopathologically, the most common tumor was adenoid cystic carcinoma (27%), followed by mucoepidermoid carcinoma (20%), and skin SCC metastatic to the parotid gland. Five-year overall survival (OS), five-year disease specific survival (DSS), and five-year disease free survival (DFS) were 50%, 50%, and 54%, respectively. Regional recurrence and distant organ metastasis developed in 5 (17%) and 9 (30%) patients, respectively. OS, DSS, and DFS were significantly decreased in patients with lymph node metastasis compared to the patients with no metastasis (p=0.002). DFS was better in Stage 1-2 patients compared to Stage 3-4 patients (p=0.019). OS and DFS were significantly in radiotherapy time in less than 45 days (p=0.01). A duration between surgery and radiotherapy of more than 42 days was associated with low DFS (p=0.042). No prognostic significance of age, gender, type of the salivary gland, T stage, tumor diameter, surgical margin, PNI, LVI, and extracapsular involvement was found among the other variables. CONCLUSION: Adjuvant RT is an efficacious and safe method of treatment in high risk patients operated on for salivary gland tumor.

Dosimetric comparison of helical tomotherapy, intensity-modulated radiation therapy, volumetric-modulated arc therapy, and 3-dimensional conformal therapy for the treatment of T1N0 glottic cancer.

Various radiotherapy planning methods for T1N0 laryngeal cancer have been proposed to decrease normal tissue toxicity. We compare helical tomotherapy (HT), linac-based intensity-modulated radiation therapy (IMRT), volumetric-modulated arc therapy (VMAT), and 3-D conformal radiotherapy (3D-CRT) techniques for T1N0 laryngeal cancer. Overall, 10 patients with T1N0 laryngeal cancer were selected and evaluated. Furthermore, 10 radiotherapy treatment plans have been created for all 10 patients, including HT, IMRT, VMAT, and 3D-CRT. IMRT, VMAT, and HT plans vs 3D-CRT plans consistently provided superior planning target volume (PTV) coverage. Similar target coverage was observed between the 3 IMRT modalities. Compared with 3D-CRT, IMRT, HT, and VMAT significantly reduced the mean dose to the carotid arteries. VMAT resulted in the lowest mean dose to the submandibular and thyroid glands. Compared with 3D-CRT, IMRT, HT, and VMAT significantly increased the maximum dose to the spinal cord It was observed that the 3 IMRT modalities studied showed superior target coverage with less variation between each plan in comparison with 3D-CRT. The 3D-CRT plans performed better at the Dmax of the spinal cord. Clinical investigation is warranted to determine if these treatment approaches would translate into a reduction in radiation therapy-induced toxicities.

Survival and prognostic factors in patients with brain metastasis: Single center experience.

PURPOSE: The purpose of this study was to evaluate the clinical status, prognostic factors and treatment modalities affecting survival in patients with brain metastasis. We aimed to evaluate the whole brain radiation therapy (WBRT) outcomes of patients with brain metastasis in our center. METHODS: Clinical data of 315 patients referred to our center between 2004 and 2014 with metastatic brain cancers were collected and analysed for possible relationships between survival time, age, gender, Karnofsky performance status (KPS), recursive partitioning analysis (RPA), primary tumor, number of brain lesions, surgery, radiation therapy scheme, extracranial metastatic status and primary disease control status. RESULTS: The average patient age of onset was 58 years. The primary tumor site was lung (68%), breast (12%), melanoma (4%), colorectal (1.6%), sarcoma (1.3%) and unknown primary disease (4.4%). The rest of the patients had other primary sites. Eighty four (26.6%) patients had single brain metastasis, 71 (22.5%) had 2 or 3 lesions, and 159 (50.4%) patients had more than 3 lesions. Leptomeningeal involvement was seen in combination of paranchymal involvement in 11 (3.5%) patients. Fifty patients had undergone surgical resection. WBRT was delivered to all of the patients. Median overall survival was 6.7 months (95% CI, 5.80-7.74). Median overall survival of patients treated with combination of surgery and WBRT was significantly better compared with those treated with WBRT alone (13.5 vs 5.5 months, p=0.0001). One- and 2- year survival was 17 and 4.7%, respectively. CONCLUSIONS: The present study concludes that brain metastasis is common in cancer patients. The best overall survival was obtained by surgery+NBRT in good-condition patients. Treatment should be tailored on an individual basis to all these patients.

Combinatorial effect of zoledronic acid and irradiation on the prevention of DMBA-induced precancerogenic changes in the mammary tissues of rats.

BACKGROUND: At present, the rates of breast cancer are continuously increasing, with over a million new cases being diagnosed worldwide each year. Hence, the development of new breast cancer chemopreventive drugs with acceptable efficacy and toxicity that are suitable for use for a protracted period of time is urgently needed. The present study investigated the potential preventive effects of zoledronic acid [ZOL] and radiotherapy [RT], both alone and in combination, on precancerogenic changes on the breast tissues of females. MATERIALS AND METHODS: Wistar rats were treated with 7,12-dimethylbenz [a] anthracene [DMBA] at the acute phase. Fifty female rats were divided into seven groups: Control group [I]; ZOL, group [II]; RT, group [III]; DMBA, group [IV]; DMBA + RT, group [V]; DMBA + ZOL, group [VI]; and DMBA + ZOL + RT, group [VII]. RESULTS: The treatment of DMBA-exposed rats with ZOL and RT, both alone and in combination, successfully upregulates the transcriptional levels of Bax, caspase-3, caspase-9, p21, and BRCA 1 in mammary tissues, which may account for the elevated apoptotic activities observed and the eventual inhibition of tumor growth. The administration of RT and ZOL both alone and in combination was found to be effective for inhibiting the DMBA-induced precancerogenic changes on breast tissues and modulating the expression of apoptosis-associated proteins in the acute phase. CONCLUSIONS: The combination of RT and ZOL was more effective than either agent alone. Our results suggest that the administration of ZOL and irradiation in combination can offer maximal protection against DMBA-induced mammary precancerogenic changes.

Is helical tomotherapy-based intensity-modulated radiotherapy feasible and effective in bilateral synchronous breast cancer? A two-center experience.

PURPOSE: This study describes the early clinical results and dosimetric parameters of intensity-modulated radiation therapy (IMRT) using a tomotherapy device in patients with primary bilateral synchronous breast cancer (PSBBC). METHODS: Fourteen patients with bilateral breast cancer were treated with tomotherapy between January 2011 and October 2014. The treatment planning objectives were to cover 95% of the planning target volume using a 95% isodose, with a minimum dose of 90% and a maximum dose of 107%. The organs at risk (OAR), such as the lungs, heart, esophagus and spinal cord, were contoured. Acute toxicity was recorded during and after radiation therapy. RESULTS: The advantages included better treatment conformity with lower dosages to minimize the risk to susceptible organs, such as the lungs, heart and spinal cord. There was improved coverage of the planning target volume, including the regional nodes, without any field junction problems. The median homogeneity index was 0.13 and the median conformity index 1.32. The median V20, V15, V10 and V5 for the total lungs were 18.5, 23.3, 24.2 and 60%, respectively. Skin acute toxicity was grade 1 in 72% and grade 2 in 14% of the patients. Esophageal acute toxicity was grade 1 in 43% of the patients. CONCLUSION: Tomotherapy delivers treatment that is well-tolerated, with high homogeneity and coverage indexes and the capability to reduce the irradiation dose received by the lungs and heart in PSBBC patients. This technique is therefore feasible and safe for the treatment of bilateral breast cancer.