Tıp Fakültesi / Faculty of Medicine

Permanent URI for this collectionhttps://hdl.handle.net/11727/1403

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    Impact of adjuvant radiotherapy and mitotane on survival in localized adrenocortical carcinoma: A retrospective cohort study
    (Başkent Üniversitesi Tıp Fakültesi, 2025) Elmali, Aysenur; Guler, Ozan Cem; Ozyigit, Gokhan; Hurmuz, Pervin; Onal, Cem; 41399138
    Objectives: Adrenocortical carcinoma (ACC) is a rare, aggressive tumor with high recurrence rates after surgery. Although radiotherapy (RT) has historically been underutilized in ACC, modern RT techniques have renewed interest in its potential role for improving local control (LC). This study evaluated long-term outcomes and prognostic factors in high-risk localized ACC treated with adjuvant RT and mitotane. Methods: In this multicenter retrospective study, 23 patients with localized, high-risk ACC who underwent complete surgical resection followed by adjuvant RT between 2003 and 2023 were analyzed. All received mitotane, and 21.6% also received platinum-based chemotherapy. RT was delivered using image-guided IMRT or VMAT to a median dose of 50.4 Gy, targeting the tumor bed with or without regional lymphatics. Survival was estimated using the Kaplan-Meier method, and prognostic factors were assessed with Cox regression analyses. Results : At a median follow-up of 84.7 months, the 5-year LC, overall survival (OS), and disease-free survival (DFS) rates were 85.5%, 58.6%, and 45.6%. Locoregional recurrence occurred in two patients (8.6%), with isolated local failure in one (4.3%). Distant metastasis (DM) developed in 47.8% and was the predominant failure pattern. On univariable analysis, age > 55 years predicted worse OS and DFS, while female sex independently predicted inferior DFS. Treatment was well tolerated, with no grade >= 3 RT-related toxicities. Conclusions: Adjuvant RT achieves excellent LC with minimal toxicity in high-risk localized ACC. These exploratory findings, limited by small cohort size, retrospective design, and absence of a comparator group, warrant confirmation in larger prospective multicenter studies.
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    Comparison of Helical and TomoDirect Techniques with Simultaneous Integrated Boost in Early Breast Cancer Patients
    (REPORTS OF PRACTICAL ONCOLOGY AND RADIOTHERAPY, 2023) Onal, Cem; Bozca, Recep; Oymak, Ezgi; Guler, Ozan Cem
    Background: The aim of the study was to perform dosimetric comparisons of helical (H) and TomoDirect (TD) plans for whole-breast irradiation (WBI) with simultaneous integrated boost (SIB) in early-stage breast cancer patients undergoing breast conserving surgery.Materials and methods: Fifty patients, 25 with left-side and 25 with right-side tumors, were determined for a treatment planning system for a total dose of 50.4Gy in 1.8Gy per fraction to WBI, with a SIB of 2.3Gy per fraction delivered to the tumor bed. The planning target volume (PTV) doses and the conformity (CI) and homogeneity indices (HI) for PTV(breast )and PTVboost, as well as organ-at-risk (OAR) doses and treatment times, were compared between the H and TD plans.Results: All plans met the PTV coverage criteria for the H plan, except for mean V107 of PTVbreast for TD plan. The H plan yielded better homogeneity and conformity of dose distribution compared to the TD plan. The ipsilateral mean lung doses were not significantly different between the two plans. The TD plans is advantageous for mean doses to the heart, contralateral breast and lung, spinal cord, and esophagus than the H plans. In both the H and TD plans, the right-sided breast patients had lower heart dose parameters than the left-sided breast patients. The TD plan is superior to the H plan in sparing the contralateral breast and lung by decreasing low-dose volumes.Conclusions: While the OAR dose advantages of TD are appealing, shorter treatment times or improved dose homogeneity and conformity for target volume may be advantageous for H plan.