Browsing by Author "Guler, Ozan Cem"

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    Estimation of secondary cancer risk after radiotherapy in high-risk prostate cancer patients with pelvic irradiation
    (WILEY, 2020-01-01) Haciislamoglu, Emel; Gungor, Gorkem; Aydin, Gokhan; Canyilmaz, Emine; Guler, Ozan Cem; Zengin, Ahmet Yasar; Yenice, Kamil Mehmet
    We aimed to estimate the risk of secondary cancer after radiotherapy (RT) in high-risk prostate cancer (HRPC) patients with pelvic irradiation. Computed tomography data of five biopsy-proven HRPC patients were selected for this study. Two different planning target volumes (PTV(1)and PTV2) were contoured for each patient. The PTV(1)included the prostate, seminal vesicles, and pelvic lymphatics, while the PTV(2)included only the prostate and seminal vesicles. The prescribed dose was 54 Gy for the PTV(1)with a sequential boost (24 Gy for the PTV2). Intensity-modulated RT (IMRT) and volumetric modulated arc therapy (VMAT) techniques were used to generate treatment plans with 6 and 10 MV photon energies with the flattening filter (FF) or flattening filter-free (FFF) irradiation mode. The excess absolute risks (EARs) were calculated and compared for the bladder, rectum, pelvic bone, and soft tissue based on the linear-exponential, plateau, full mechanistic, and specific mechanistic sarcoma dose-response model. According to the models, all treatment plans resulted in similar risks of secondary bladder or rectal cancer and pelvic bone or soft tissue sarcoma except for the estimated risk of the bladder according to the full mechanistic model using IMRT((6MV
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    National Multi-Center Observational Retrospective Study to Understand Treatment Patterns and Outcomes for Stage III Non-Small Cell Lung Cancer Patients in Turkey: Turkish Society for Radiation Oncology Study, STONE Trial
    (AKAD DOKTORLAR YAYINEVI, 2022-01-01) Onal, Cem; Demiral, Ayse Nur; Atalar, Banu; Yalman, Deniz; Dagoglu, Nergiz; Hurmuz, Pervin; Erpolat, Petek; Akyurek, Serap; Gul, Sute Karabulut; Berber, Tanju; Guler, Ozan Cem; Umay, Cenk; Sert, Fatma; Karahacioglu, Eray; Birgi, Sumerya Duru; Yaprak, Gokhan; Saglam, Esra Kaytan
    This study investigated treatment patterns and outcomes in patients with inoperable stage III non-small cell lung cancer (NSCLC) treated with radiotherapy (RT) in Turkey. We included 492 patients with stage III NSCLC in this multi-center retrospective study. Pa-tient demographics, clinical characteristics, and clinical treatment patterns from the time of the initial diagnosis to disease progression were recorded. Additionally, the prognostic factors predicting overall survival (OS) and progression-free survival (PFS) were analyzed. For the initial treatment, 429 patients (89.2\%) received chemotherapy and RT, whereas 53 patients (10.8\%) were treated only with RT. The first disease progression occurred in 288 patients (58.4\%) at 9.3 months (median) after the initial treatment, and 64.6\% re-ceived treatment after first progression. The second disease progression occurred in 30 patients, and 20 patients (66.7\%) received treatment. Median OS and PFS were 27.0 months and 13.4 months, respectively. Age (p< 0.001), stage (p= 0.04), poor performance score (PS) (p= 0.03) and RT doses (p= 0.002) were independent predictors for OS and PFS in our multivariate analysis. Additional significant predictors for OS in the multivariate analysis were gender (p= 0.004), treatment period (0.02), and irradiation technique (p= 0.02). Disease progression occurred in nearly 58\% of the patients, and one-third of these patients remained untreated during the disease progression. These findings indicate a need for additional treatment options in patients with unresectable stage III NSCLC with high-risk features, namely older age, stage IIIB disease, poor PS, and lower RT doses.