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    A New Perspective on the Effectiveness of FDG PET/CT in Predicting KRAS Mutation in Colon Cancer Cases
    (Mary Ann Liebert, Inc, 2024) Tamer, Fatih; Yararbas, Ulkem
    Aim: The main aim of this study was to evaluate the effectiveness of 18F-fluorodeoxyglucose (18FDG) positron emission tomography/computerized tomography (PET/CT) parameters in predicting the Kristen rat sarcoma viral oncogene(KRAS) mutation status of patients with colon cancer.Materials and Methods: Between April 2013 and December 2020, 79 patients who were diagnosed with colon cancer by colonoscopy underwent staging 18FDG PET/CT with this diagnosis and met all the inclusion criteria were included in this study. Clinical and prognostic features and also imaging (18FDG PET/CT and magnetic resonance imaging) reports of the patients were collected and analyzed retrospectively.Results: KRAS mutation was seen in 32 of patients (40.5%). No significant difference was observed between KRAS mutant and wild-type patients in terms of clinical features (tumor location, findings regarding metastasis, T stage, and tumor differentiation grade in patients who underwent surgery) and overall survival. Progression-free survival was significantly shorter in KRAS mutant patients (p = 0.018). Primary tumor standardized uptake value (SUVmean) was significantly higher in KRAS mutant cases in the whole group (p = 0.024) and in patients in whom KRAS analysis was performed only in the primary lesion (p = 0.036). The cutoff value for predicting KRAS mutation status was 7.01 g/mL (area under the curve [AUC]: 0.650, confidence interval [CI] 95%, 0.56-0.74).Conclusions: When colon and rectal cancer cases were evaluated separately, the primary tumor SUVmean value was significantly higher in KRAS mutant colon cancer cases. However, its effectiveness in predicting KRAS mutation status was low, similar to other parameters in the literature.
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    Alterations in 18F-FDG Uptake Patterns may Limit Cross-sectional Evaluation of Adrenal Adenomas Using Single 18F-FDG PET/CT Imaging
    (Galenos Publ House, 2023) Tamer, Fatih; Yararbas, Ulkem
    Adrenal adenomas are observed in up to 7% of the population and are predominantly non-functional, increased 18F-fluorodeoxyglucose (FDG) uptake is seen in only a small portion of them on F-18-FDG positron emission tomography/computed tomography (PET/CT) imaging. In this report, we present the sequential(18)F-FDG PET/CT imaging findings of 2 patients with radiologically or pathologically confirmed adrenal adenomas who had severely altered F-18-FDG uptake patterns in adrenal lesions in different imaging studies of the same patient. In light of these findings, we wanted to highlight that evaluating adrenal adenomas as cross-sectional with semi-quantitative PET/CT parameters obtained from single imaging may cause misinterpretation.
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    Incidental Meningioma With Altered PSMA Expression After Systemic Hormone Therapy and Local Radiotherapy Detected by 68Ga-PSMA PET/CT
    (Lippincott Williams & Wilkins, 2023) Tamer, Fatih; Omur, Ozgur
    A 59-year-old man underwent radical prostatectomy for adenocarcinoma in 2009. Because of the progression of PSA levels, a Ga-68-PSMA PET/CT scan was performed in January 2020. A suspicious uptake was detected in the left cerebellar hemisphere, and there was no evidence of distant metastatic disease other than recurrent malignancy in the prostatectomy bed. MRI revealed a meningioma located in the left cerebellopontine angle. Although PSMA uptake of the lesion increased in the first imaging after hormone therapy, partial regression was noted after radiotherapy applied to this region.
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    Long-term Intense 18F-FDG Uptake by the Homeostatic Matrix- associated Inflammatory Response May Mimic Malignancy Recurrence
    (Galenos Publ House, 2023) Tamer, Fatih; Yazici, Bulent; Oral, Aylin; Akgun, Aysegul
    A 70-year-old man underwent right upper lobectomy for lung adenocarcinoma. During the operation, hemostatic matrix (as known Floseal (R)) was used to prevent pulmonary laceration-associated bleeding. When F-18-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography was performed for staging after surgery, intense F-18-FDG uptake was observed in the cicatricial fibrotic tissue in the operation area, and no significant change was observed in that area during the 4-year follow-up. Because it remained stable for several years without treatment, this finding was thought to be due to a foreign body reaction caused by the homeostatic material.
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    The real-world outcomes of Lutetium-177 PSMA-617 radioligand therapy in metastatic castration-resistant prostate cancer: Turkish Oncology Group multicenter study
    (John Wiley and Sons Inc, 2024) Almuradova, Elvina; Seyyar, Mustafa; Arak, Hacı; Tamer, Fatih; Kefeli, Umut; Koca, Sinan; Sen, Erdem
    Metastatic castration-resistant prostate cancer (mCRPC) remains a challenging condition to treat despite recent advancements. This retrospective study aimed to assess the activity and tolerability of Lutetium-177 (Lu-177) PSMA-617 radioligand therapy (RLT) in mCRPC patients across multiple cancer centers in Turkey. The study included 165 patients who received at least one cycle of Lu-177 PSMA-617 RLT, with the majority having bone metastases and undergone prior treatments. Prostate-specific antigen (PSA) levels were assessed before each treatment cycle, and the biochemical response was evaluated in accordance with the Prostate Cancer Work Group 3 Criteria. The PSA decline of ?50% was classified as a response, while an increase of ?25% in PSA levels was indicative of progressive disease. Neither response nor progression was considered as stable disease. The Lu-177 PSMA-617 RLT led to a significant PSA response, with 50.6% of patients achieving a >50% decrease in PSA levels. Median overall survival (OS) and progression-free survival were 13.5 and 8.2 months, respectively. Patients receiving Lu-177 PSMA-617 RLT in combination with androgen receptor pathway inhibitors (ARPIs) had a higher OS compared to those receiving Lu-177 PSMA-617 RLT alone (18.2 vs 12.3 months, P =.265). The treatment was generally well-tolerated, with manageable side effects such as anemia and thrombocytopenia. This study provides real-world evidence supporting the effectiveness and safety of Lu-177 PSMA-617 RLT in mCRPC patients, particularly when used in combination with ARPIs. These findings contribute to the growing body of evidence on the potential benefits of PSMA-targeted therapies in advanced prostate cancer. © 2023 UICC.