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Öğe Adult Rhabdomyosarcoma: Clinical Features and Radiotherapy Outcomes-The Turkish Oncology Group (TOG) Bone and Soft Tissue Sarcoma Study Group(Kare Publ, 2018) Korkmaz Kirakli, Esra; Iribas, Ayca; Ergen, Arzu; Atalar, Banu; Adaoglu, Fulya; Onder Dincbas, Fazilet; Darendeliler, Emin; Anacak, Yavuz; Kamer, SerraOBJECTIVE Although rhabdomyosarcoma (RMS) is the most frequent soft tissue sarcoma diagnosed in childhood, it represents only 2%-5% of adult soft tissue sarcomas. The aim of the present study was to better understand the clinical characteristics, treatment approaches, and outcomes of patients with adult RMS who received radiotherapy (RT) as a component of their multidisciplinary management since there are scarce data on adult RMS due to its rarity. METHODS The medical records of patients with adult RMS who were >= 18 years old and treated with RT between January 1995 and August 2016 in four different radiation centers were evaluated in terms of clinical characteristics, treatment, and follow-up data retrospectively. RESULTS There were 28 patients. The median age at diagnosis was 28 (19-53) years. The most common site of involvement was the head and neck (25%), and parameningeal region involvement was prominent (92%) among them. In general, unfavorable site of involvement was markedly higher than favorable ones (82% vs. 18%). Alveolar and pleomorphic subtypes compromised 75% of the cases. Fifteen patients had surgery, 26 chemotherapy, 10 radical intent of RT, 9 adjuvant, 3 preoperative, and 6 palliative. The follow-up time was from 3 to 235 (median 18) months, disease-free survival was between 2 and 48 (median 12) months, and 5-year overall survival (OS) was 25% (median OS 20 (4-235) months). There were significant differences in terms of survival according to histopathological subtypes (p: 0.017), risk groups (p<0.001), Intergroup Rhabdomyosarcoma Study Group (IRSG) grouping and IRSG staging (p<0.001). CONCLUSION Adult RMS has unfavorable clinical presentation and worse outcome compared with pediatric RMS. Histopathological subtype and risk grouping to define the prognosis used in pediatric cases also might be valid in adult RMS.Öğe Adult Rhabdomyosarcoma: Clinical Features and Radiotherapy Outcomes—The Turkish Oncology Group (TOG) Bone and Soft Tissue Sarcoma Study Group(2018) Kıraklı, Esra Korkmaz; İribaş, Ayça; Ergen, Arzu; Atalar, Banu; Ağaoğlu, Fulya; Dınçbaş, Fazilet Önder; Anacak, YavuzOBJECTIVE Although rhabdomyosarcoma (RMS) is the most frequent soft tissue sarcoma diagnosed in childhood, it represents only 2%–5% of adult soft tissue sarcomas. the aim of the present study was to better understand the clinical characteristics, treatment approaches, and outcomes of patients with adult RMS who received radiotherapy (RT) as a component of their multidisciplinary management since there are scarce data on adult RMS due to its rarity. METHODS the medical records of patients with adult RMS who were ?18 years old and treated with RT between January 1995 and August 2016 in four different radiation centers were evaluated in terms of clinical characteristics, treatment, and follow-up data retrospectively. RESULTS There were 28 patients. the median age at diagnosis was 28 (19–53) years. the most common site of involvement was the head and neck (25%), and parameningeal region involvement was prominent (92%) among them. in general, unfavorable site of involvement was markedly higher than favorable ones (82% vs. 18%). Alveolar and pleomorphic subtypes compromised 75% of the cases. Fifteen patients had surgery, 26 chemotherapy, 10 radical intent of RT, 9 adjuvant, 3 preoperative, and 6 palliative. the follow-up time was from 3 to 235 (median 18) months, disease-free survival was between 2 and 48 (median 12) months, and 5-year overall survival (OS) was 25% (median OS 20 (4–235) months). There were significant differences in terms of survival according to histopathological subtypes (p: 0.017), risk groups (p<0.001), Intergroup Rhabdomyosarcoma Study Group (IRSG) grouping and IRSG staging (p<0.001). CONCLUSION Adult RMS has unfavorable clinical presentation and worse outcome compared with pediatric RMS. Histopathological subtype and risk grouping to define the prognosis used in pediatric cases also might be valid in adult RMS.Öğe Association between the rates of synchronous and metachronous metastases: Anaylysis of SEER data(Ubm Medica, 2007) Anacak, Yavuz; Meyer, Jeff J.; Marks, Lawrence B.Patients with cancer are usually staged based on the presence of detectable regional and/or distant disease. However, staging is inexact and cM0 patients may have microscopic metastases (cM0pM1) that later cause relapse and death. Since the clinical tools used to stage patients are fairly similar for different tumors, the ratio of the rates of metachronous to synchronous metastases should be similar for different tumors (hypothesis #1). Improvements in diagnostic tools should have caused the ratio of metachronous-to-synchronous metastases to have decreased over time (hypothesis #2). Finally, the fraction of patients with either metachronous or synchronous metastases should have declined over time due to increased screening and earlier diagnoses (hypothesis #3). To test these hypotheses, Surveillance, Epidemiology, and End Results (SEER) data from 1973-1998 were analyzed for 19 solid tumors. A linear relationship was seen between the rates of metachronous and synchronous metastases, with modestly strong correlation coefficients, consistent with hypothesis #1. Over time, changes in staging methods have not significantly altered the ratio of metachronous/synchronous metastases, contrary to hypothesis #2. Also over time, a decrease in the number of patients with metastases was found, consistent with hypothesis #3. Therefore, the rate of anticipated metachronous metastases can be estimated from the rate of clinically evident metastases at presentation. Changes in screening/staging of disease over time may have reduced the overall fraction of patients with metastases.Öğe A BRIEF OVERVIEW TO PEDIATRIC GRAY ZONE LYMPHOMAS(Wiley, 2022) Ataseven, Eda; Ozek, Gulcihan; Ozsan, Nazan; Kamer, Serra; Anacak, Yavuz; Aksoylar, Serap; Kantar, Mehmet[No Abstract Available]Öğe Changes in radiotherapy practice during COVID-19 outbreak in Turkey: A report from the Turkish Society for Radiation Oncology(Elsevier Ireland Ltd, 2020) Anacak, Yavuz; Onal, Cem; Ozyigit, Gokhan; Agaoglu, Fulya; Akboru, Halil; Akyurek, Serap; Saglam, Esra Kaytan[No Abstract Available]Öğe Combining radiotherapy with immunotherapy(Marmara Univ, Fac Medicine, 2015) Anacak, Yavuz; Kamer, Serra; Sert, FatmaIt has long been known that radiation destroys the tumors by killing cells. However, immunotherapy is developing rapidly, combination of immunotherapy with chemotherapy and radiotherapy seems to be a viable option. Preclinical studies combining immunotherapy with radiotherapy resulted in promising data, where manipulating immune response enhances the effects of radiation. There are many ways of immunotherapy-radiotherapy combination, and the field is open for clinical research. This paper reviews the current situation on this topic.Öğe Current and projected gaps in the availability of radiotherapy in the Asia-Pacific region: a country income-group analysis(Elsevier Science Inc, 2024) Abu Awwad, Dania; Shafiq, Jesmin; Delaney, Geoffrey Paul; Anacak, Yavuz; Bray, Freddie; Flores, Jerickson Abbie; Gondhowiardjo, SoehartatiBackground Cancer incidence and mortality is increasing rapidly worldwide, with a higher cancer burden observed in the Asia-Pacific region than in other regions. To date, evidence-based modelling of radiotherapy demand has been based on stage data from high-income countries (HIC) that do not account for the later stage at presentation seen in many low-income and middle-income countries (LMICs). We aimed to estimate the current and projected demand and supply in megavoltage radiotherapy machines in the Asia-Pacific region, using a national income-group adjusted model. Methods Novel LMIC radiotherapy demand and outcome models were created by adjusting previously developed models that used HIC cancer staging data. These models were applied to the cancer case mix (ie, the incidence of each different cancer) in each LMIC in the Asia-Pacific region to estimate the current and projected optimal radiotherapy utilisation rate (ie, the proportion of cancer cases that would require radiotherapy on the basis of guideline recommendations), and to estimate the number of megavoltage machines needed in each country to meet this demand. Information on the number of megavoltage machines available in each country was retrieved from the Directory of Radiotherapy Centres. Gaps were determined by comparing the projected number of megavoltage machines needed with the number of machines available in each region. Megavoltage machine numbers, local control, and overall survival benefits were compared with previous data from 2012 and projected data for 2040. Findings 57 countries within the Asia-Pacific region were included in the analysis with 9.48 million new cases of cancer in 2020, an increase of 2.66 million from 2012. Local control was 7.42% and overall survival was 3.05%. Across the Asia-Pacific overall, the current optimal radiotherapy utilisation rate is 49.10%, which means that 4.66 million people will need radiotherapy in 2020, an increase of 1.38 million (42%) from 2012. The number of megavoltage machines increased by 1261 (31%) between 2012 and 2020, but the demand for these machines increased by 3584 (42%). The Asia-Pacific region only has 43.9% of the megavoltage machines needed to meet demand, ranging from 9.9-40.5% in LMICs compared with 67.9% in HICs. 12 000 additional megavoltage machines will be needed to meet the projected demand for 2040. Interpretation The difference between supply and demand with regard to megavoltage machine availability has continued to widen in LMICs over the past decade and is projected to worsen by 2040. The data from this study can be used to provide evidence for the need to incorporate radiotherapy in national cancer control plans and to inform governments and policy makers within the Asia-Pacific region regarding the urgent need for investment in this sector. Copyright (c) 2024 Elsevier Ltd. All rights reserved.Öğe Daily subcutaneous amifostine administration during irradiation of pediatric head and neck cancers(Wiley-Liss, 2007) Anacak, Yavuz; Kamer, Serra; Haydaroglu, AyferFive pediatric patients with head and neck cancers were treated with radiotherapy. Subcutaneous injections of 200 mg flat dose amifostine were given 30 min prior to radiation fractions. A total of 129 amifostine injections were done. Grade 3 nausea occurred three times and emesis only once. Hypotension, hypocalcemia, or allergic reactions following injections were not recorded. No grade 3 or 4 mucosal or skin reactions occurred. After 16 months, all patients were alive and disease-free. There were no grade 3 or 4 side effects of radiotherapy on follow-up. Further studies with more patients are required to determine the role of amifostine in pediatric radiation oncology, but these data should contribute to the clinical spectrum of amifostine use in pediatric oncology.Öğe DEVELOPMENT OF CLINICAL GUIDELINES FOR THE TREATMENT OF LOW GRADE GLIOMAS IN LOWER AND LOWER MIDDLE INCOME COUNTRIES - A SIOP PODC INITIATIVE(Oxford Univ Press Inc, 2016) Hessissen, Laila; Amayiri, Nisreen; Mushtaq, Naureen; Sirachainan, Nongnuch; Anacak, Yavuz; Mitra, Dipayan; Figaji, Anthony; Schouten-van Meeteren, Antoinette; Sullivan, Michael; Davidson, Alan; Parkes, Jeannette; Bouffet, Eric; Bailey, SimonÖğe DIFFUSE PONTINE GLIOMAS OF THE CHILDHOOD: DOES TEMOZOLOMIDE IMPROVE SURVIVAL?(Wiley Periodicals, Inc, 2012) Anacak, Yavuz; Oniz, Haldun; Kantar, Mehmet; Kadioglu, Bengu; Kara, Gulsen; Kamer, Serra; Vergin, Canan; Cetingul, NazanÖğe Ege Üniversitesi Hastanesi çocukluk çağı tümörlerinde epidemiyoloji ve sağ kalım özellikleri(2019) Ataseven, Eda; Kantar, Mehmet; Anacak, Yavuz; Kamer, Serra; Ertan, Yeşim; Caner, Ayşe; Çetingül, NazanAmaç: Her yıl Dünyada 0-19 yaş arası yaklaşık 300.000 olgu kanser tanısı almaktadır. Gelişmiş ve gelişmekte olan ülkelerde çocukluk çağı kanserlerinin dağılımı ve sağ kalım hızlarında belirgin farklılık bildirilmektedir. Bu çalışmada amacımız merkezimizde kayıtlı olan çocukluk çağı kanser olgularının epidemiyolojik özelliklerini ve sağ kalım hızlarını değerlendirmektir. Gereç ve Yöntem: Merkezimizde 1992-2017 tarihleri arasında 0-19 yaş arasında kanser tanısı alan 4602 hastanın verileri Ege Üniversitesi Kanserle Savaş ve Araştırma Merkezi kayıtları kullanılarak geriye dönük olarak değerlendirildi. Yaşa, cinsiyete, yıllara göre tümör dağılımları ve genel sağ kalım hızları değerlendirildi. Bulgular: Olguların %55,3’ü erkek, %44,7’si kız ve erkek/kız oranı 1,23/1 idi. Olguların ortalama tanı yaşı 5,6 yıl idi. Merkezimizde en sık lösemi (%25,6), ikinci sıklıkta santral sinir sistemi tümörleri (%23,4), üçüncü sıklıkta ise lenfomalar (%14,2) görülmekteydi. Olguların ortalama izlem süresi 41,4 ay (0-316 ay) idi. Tüm olgular için beş yıllık genel sağ kalım hızı %74 saptandı. Sonuç: Merkezimizdeki kanser tiplerinin dağılımı ve genel sağ kalım hızları literatür ile benzerdir. Ülkemiz verileri ile karşılaştırıldığında genel sağ kalım hızlarımızın daha iyi olduğu görülmüştür. Bu sonuçlar sağ kalım hızlarının bölgeden bölgeye değiştiğini, bu değişimde hasta ve hasta yakınının farkındalık düzeyinin, gerekli tedaviye ulaşabilme imkanının ve multidisipliner merkezlerin varlığının önemini düşündürmektedir.Öğe THE ESSENTIAL ROLE OF RADIOTHERAPY IN THE TREATMENT OF MERKEL CELL CARCINOMA: A STUDY FROM THE RARE CANCER NETWORK(Elsevier Science Inc, 2011) Ghadjar, Pirus; Kaanders, Johannes H.; Poortmans, Philipp; Zaucha, Renata; Krengli, Marco; Lagrange, Jean L.; Ozsoy, Orhan; Nguyen, Tan D.; Miralbell, Raymond; Baize, Adele; Boujelbene, Noureddine; Collen, Timothy; Scandolaro, Luciano; Untereiner, Michel; Goldberg, Hadassah; Pesce, Gianfranco A.; Anacak, Yavuz; Friedrich, Esther E.; Aebersold, Daniel M.; Beer, Karl T.Purpose: To evaluate the role of postoperative radiotherapy (RT) in Merkel cell carcinoma (MCC). Methods and Materials: A retrospective multicenter study was performed in 180 patients with MCC treated between February 1988 and September 2009. Patients who had had surgery alone were compared with patients who received surgery and postoperative RT or radical RT. Local relapse-free survival (LRFS), regional relapse-free survival (RRFS), and distant metastasis-free survival (DMFS) rates were assessed together with disease-free survival (DFS), cancer-specific survival (CSS), and overall survival (OS) rates. Results: Seventy-nine patients were male and 101 patients were female, and the median age was 73 years old (range, 38-93 years). The majority of patients had localized disease (n = 146), and the remaining patients had regional lymph node metastasis (n = 34). Forty-nine patients underwent surgery for the primary tumor without postoperative RT to the primary site; the other 131 patients received surgery for the primary tumor, followed by postoperative RT (n = 118) or a biopsy of the primary tumor followed by radical RT (n = 13). Median follow-up was 5 years (range, 0.2-16.5 years). Patients in the RT group had improved LRFS (93% vs. 64%; p < 0.001), RRFS (76% vs. 27%; p < 0.001), DMFS (70% vs. 42%; p = 0.01), DFS (59% vs. 4%; p < 0.001), and CSS (65% vs. 49%; p = 0.03) rates compared to patients who underwent surgery for the primary tumor alone; LRFS, RRFS, DMFS, and DFS rates remained significant with multivariable Cox regression analysis. However OS was not significantly improved by postoperative RT (56% vs. 46%; p = 0.2). Conclusions: After multivariable analysis, postoperative RT was associated with improved outcome and seems to be an important component in the multimodality treatment of MCC. (C) 2011 Elsevier Inc.Öğe Evaluation of Dose Distribution in Field Junction Area and Risk Organs for Supine and Prone Treatment Techniques in Craniospinal Irradiation(Kare Publ, 2021) Unlenen, Onur; Kamer, Serra; Olacak, Nezahat; Koylu, Murat; Olacak, Ibrahim; Anacak, Yavuz; Yalman, DenizOBJECTIVE The aim of this study is to investigate dose distributions in junction regions and organs at risk in asymmetric collimation techniques and divergence matching techniques used in craniospinal treatments. METHODS In the anthropomorphic phantom, the junction area and organ at risk doses were determined for eight different craniospinal irradiation (CSI) techniques with the help of thermoluminescent dosimeter (TLD) and treatment planning system (TPS). These techniques differ in terms of the parameters of the table being angled/un-angled, using block/multi-leaf collimator, and being in supine/prone position. RESULTS There was no statistically significant difference between TPS and TLD doses of all techniques. The lowest doses of cribriform plate are 1.82 Gy in PM, and 1.84 Gy in PAM. The lowest dose in lenses is 0.19 Gy in PB. The lowest dose of thyroid is 1.27 Gy in PB and highest dose of PAM is 1.35 Gy. Average small intestine dose of 1.92 Gy in non-table angle decreases to 1.08 Gy with table angle. The highest kidney doses are 0.14 Gy in SM. Ovaries take an average dose of 0.09 Gy in non-table angled and average of 0.13 Gy in table-angled techniques. CONCLUSION It has been determined that CSI technique in supine without table angle and protected with special blocks, is superior to other techniques due to its better dose homogeneity in treatment volume, providing immobilization in daily use and ease of application.Öğe Evre I seminom tanılı 79 vakanın postoperatif radyoterapi sonuçları.(2002) Özsaran, Zeynep; Anacak, Yavuz; Yalman, Deniz; Korkmaz, Elif; Akcay, C. Akay; Haydaroğlu, Ayfer…Öğe Evre-3 küçük hücreli dışı akciğer kanserlerinde eksternal radyoterapi ile kombine endobronşial HDR brakiterapi(Ege Üniversitesi, 1994) Anacak, Yavuz; Haydaroğlu, AyferÖZET Endobronşial brakiterapinin ileri evre nonmetastatik küçük hücreli dışı akciğer kanserlerinde lokal kontrola ve sağkalma olan etkisini araştırmak amacıyla 20 olguya eksternal radyoterapi ile kombine brakiterapi uygulanmıştır. Olgulann tümü Evre IHA ve IIIB olup, 60 Gy (30x2Gy) eksternal radyoterapi ve 15 Gy (3x5Gy) endobronşial brakiterapi ile tedavi edilmişlerdir. Tedavi sonrası değerlendirmede semptomlarda %45-90 arasında palyasyon sağlanmış ve olgulann %57.8 ' inde tedaviye tam yanıt, %73.5'inde ise tam + kısmi yanıt alınmıştır. Tedavinin sağkalıma yaptığı etkiyi değerlendirmek için henüz erken olmasına rağmen 6 aylık sağkalım %73.1 olarak bulunmuştur. Hasta yaşı ve kaynak aktivitesi ile tedavi yanıtı arasında istatistiksel yönden anlamlı bir farklılık görülmezken, Evre-IIIA olguların Evre-IIIB olgulara göre anlamlı olarak daha iyi yanıt verdiği saptanmıştır. Tedavi sırasında ve sonrasında önemli bir komplikasyon görülmemiştirÖğe Flow Cytometric Analysis of Depletion and Recovery Kinetics of T Cell Subsets in Rats After Total-Body-Irradiation: Footprints of Treg-Augmented Immunosuppression(Kare Publ, 2018) Korkmaz Kirakli, Esra; Anacak, Yavuz; Haydaroglu, AyferOBJECTIVE Total-body-irradiation (TBI) causes significant immunosuppression, but different lymphocyte subsets have various radiosensitivities. Regulatory T (Treg) cells, which are crucial for self-tolerance and are potent suppressors of antitumor immunity are found to be resistant to radiotherapy (RT) compared with T helper (Th) cells and Cytotoxic-T lymphocytes (CTL) in both in-vivo and in-vitro studies, but the data on this subject is relatively scarce. Besides, recent developments in the context of combination of immunotherapy with RT compelled us to revisit the concept of radiation-induced quantitative and functional changes in lymphocyte subsets by flow cytometry using animal models with the aim of transitioning the findings to clinical studies. METHODS Twenty-three Swiss albino rats were exposed to TBI at a single fraction of 5 Gy. Immediately prior to irradiation, at time points of 1 day and 7 and 14 days post-TBI, flow cytometric analyses were performed. RESULTS There has been statistically significant decrease in all T lymphocyte subsets at 1, 7 and 14 days post-TBI. The decrease in Th subset was more pronounced compared to CTL. Baseline CD4+/CD8+ ratio was 0.85 which significantly decreased to 0.29 1 day post-TBI, then increased steadily in subsequent measurements and reached near normal. The number of Treg cells markedly declined to 6.5% of baseline value one day after TBI, and then steadily increased during the follow-up. By the end of 14 days, it reached half of its baseline value. CONCLUSION Radiation-induced immunosuppression may be explained not only by the decrease in lymphocyte cell number but also by the relative increase in Treg cell number because the higher regenerative capacity may present an additional role.Öğe Flow Cytometric Analysis of Depletion and Recovery Kinetics of T Cell Subsets in Rats After Total-BodyIrradiation: Footprints of Treg-Augmented Immunosuppression(2018) Kıraklı, Esra Korkmaz; Anacak, Yavuz; Haydaroğlu, AyferOBJECTIVE Total-body-irradiation (TBI) causes significant immunosuppression, but different lymphocyte subsets have various radiosensitivities. Regulatory T (Treg) cells, which are crucial for self-tolerance and are potent suppressors of antitumor immunity are found to be resistant to radiotherapy (RT) compared with T helper (Th) cells and Cytotoxic-T lymphocytes (CTL) in both in-vivo and in-vitro studies, but the data on this subject is relatively scarce. Besides, recent developments in the context of combination of immunotherapy with RT compelled us to revisit the concept of radiation-induced quantitative and functional changes in lymphocyte subsets by flow cytometry using animal models with the aim of transitioning the findings to clinical studies. METHODS Twenty-three Swiss albino rats were exposed to TBI at a single fraction of 5 Gy. Immediately prior to irradiation, at time points of 1 day and 7 and 14 days post-TBI, flow cytometric analyses were performed. RESULTS There has been statistically significant decrease in all T lymphocyte subsets at 1, 7 and 14 days post-TBI. the decrease in Th subset was more pronounced compared to CTL. Baseline CD4+/CD8+ ratio was 0.85 which significantly decreased to 0.29 1 day post-TBI, then increased steadily in subsequent measurements and reached near normal. the number of Treg cells markedly declined to 6.5% of baseline value one day after TBI, and then steadily increased during the follow-up. By the end of 14 days, it reached half of its baseline value. CONCLUSION Radiation-induced immunosuppression may be explained not only by the decrease in lymphocyte cell number but also by the relative increase in Treg cell number because the higher regenerative capacity may present an additional role.Öğe Flow Cytometric Analysis of Depletion and Recovery Kinetics of T Cell Subsets in Rats After Total-BodyIrradiation: Footprints of Treg-Augmented Immunosuppression(2018) Kıraklı, Esra Korkmaz; Anacak, Yavuz; Haydaroğlu, AyferOBJECTIVE Total-body-irradiation (TBI) causes significant immunosuppression, but different lymphocyte subsets have various radiosensitivities. Regulatory T (Treg) cells, which are crucial for self-tolerance and are potent suppressors of antitumor immunity are found to be resistant to radiotherapy (RT) compared with T helper (Th) cells and Cytotoxic-T lymphocytes (CTL) in both in-vivo and in-vitro studies, but the data on this subject is relatively scarce. Besides, recent developments in the context of combination of immunotherapy with RT compelled us to revisit the concept of radiation-induced quantitative and functional changes in lymphocyte subsets by flow cytometry using animal models with the aim of transitioning the findings to clinical studies. METHODS Twenty-three Swiss albino rats were exposed to TBI at a single fraction of 5 Gy. Immediately prior to irradiation, at time points of 1 day and 7 and 14 days post-TBI, flow cytometric analyses were performed. RESULTS There has been statistically significant decrease in all T lymphocyte subsets at 1, 7 and 14 days post-TBI. The decrease in Th subset was more pronounced compared to CTL. Baseline CD4+/CD8+ ratio was 0.85 which significantly decreased to 0.29 1 day post-TBI, then increased steadily in subsequent measurements and reached near normal. The number of Treg cells markedly declined to 6.5% of baseline value one day after TBI, and then steadily increased during the follow-up. By the end of 14 days, it reached half of its baseline value. CONCLUSION Radiation-induced immunosuppression may be explained not only by the decrease in lymphocyte cell number but also by the relative increase in Treg cell number because the higher regenerative capacity may present an additional role.Öğe Gastric and non gastric marginal zone B cell lymphoma of Mucosa Assocıated Lymphoıd Tissue a single center experience(2007) Vural, F; Ocakcı, Serkan; Dubova, Senem; Soyer, Nur; Saydam, Güray; Cagırgan, S; Anacak, Yavuz…Öğe The interaction of ionizing radiation and silicone medical implants: Evaluation of the effects on radiotherapy dose distribution and alteration in the physical properties of the silicone(Pergamon-Elsevier Science Ltd, 2023) Hoca, Sinan; Olacak, Nezahat; Anacak, YavuzSilicone prostheses are implanted inside the human body for medical aesthetics and reconstructive reasons. The presence of a silicone prosthesis around the radiotherapy volume may alter radiotherapy dose distribution and cause overdose and underdose areas in the target volumes and organs at risk. The interaction of silicone with radiation may be two-sided since high dose radiation may cause alteration of the physical and chemical prop-erties of silicone which further contributes to changes in the dose distribution. The aim of this study was to evaluate the changes in radiation dose distribution caused by silicone and the effects of irradiation on silicone elastomer prostheses. A special set-up was prepared in the water phantom to obtain depth dose and profile data for non-irradiated silicone blocks prior to the irradiation schedule. Entrance and exit doses between silicone and water medium were measured using thermoluminescence dosimetry (TLD). Hardness tests on silicone blocks were performed by using Tronic Shore A Durometer device and density tests were performed by using Scaltec density determination instrument. Irradiation of the silicone was performed using a linear accelerator with 6 MV and 10 MV photon energies, 2 Gy daily fractions in 5 weeks were delivered to a total dose of 50 Gy. After the completion of 5 weeks schedule depth doses, profile measurements, entrance-exit doses and density-hardness tests were repeated. The non-irradiated silicone blocks affected the depth dose distribution in the water phantom to a maximum dose reduction of 1.5% for 6 MV and 1.6% for 10 MV. After the 5 weeks of irradiation, depth dose reduction increased to 2.5% for 6 MV and 2.0% for 10 MV. Silicone blocks affected the dose profile as well: maximum dose difference was 2.7% for 6 MV and 2.4% for 10 MV for non-irradiated silicone, 2.6% for 6 MV, and 2% for 10 MV after 50 Gy. However, these changes in depth dose and profile data in non-irradiated and irradiated silicone were not significant. There was up to an 8% dose decrease in exit doses beyond the silicone with the use of a single direct irradiation field, which is expected to be reduced with multi-field radiotherapy. The physical properties of the non-irradiated and irradiated silicone measured by hardness and density tests were similar. The only physical difference we noted was the discoloration of silicone to a yellowish color. According to our results silicone elastomer prostheses did not have significant effects on dose distribution after 50 Gy irradiation, and radiation doses used for radiotherapy did not alter the physical properties of silicone blocks except for discoloration.
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