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    Gastric Cancer Surgery Before and During the COVID-19 Pandemic in Turkey: A Multicenter Comparison of Prognostic Factors, Mortality, and Survival
    (Mdpi, 2025) Dalda, Yasin; Akbulut, Sami; Ogut, Zeki; Yilmaz, Serkan; Sahin, Emrah; Dalda, Ozlem; Tuncer, Adem
    Background/Objectives: The COVID-19 pandemic disrupted global cancer care. This study compared gastric cancer surgical outcomes before and during the pandemic in Turkey. We also aimed to analyze the impact of the pandemic and factors on survival and mortality in gastric cancer patients. Materials and Methods: This retrospective, multicenter cohort study included 324 patients from three tertiary centers in Turkey who underwent gastric cancer surgery between January 2018 and December 2022. Patients were stratified into Pre-COVID-19 (n = 150) and COVID-19 Era (n = 174) groups. Comprehensive demographic, surgical, pathological, and survival data were analyzed. To identify factors independently associated with postoperative mortality, a multivariable logistic regression model was applied. For evaluating predictors of long-term survival, multivariable Cox proportional hazards regression analysis was conducted. Results: The median time from diagnosis to surgery was comparable between groups, while the time from surgery to pathology report was significantly prolonged during the pandemic (p = 0.012). Laparoscopic surgery (p = 0.040) and near-total gastrectomy (p = 0.025) were more frequently performed in the Pre-COVID-19 group. Although survival rates between groups were similar (p = 0.964), follow-up duration was significantly shorter in the COVID-19 Era (p < 0.001). Comparison between survivor and non-survivor groups showed that several variables were significantly associated with mortality, including larger tumor size (p < 0.001), greater number of metastatic lymph nodes (p < 0.001), elevated preoperative CEA (p = 0.001), CA 19-9 (p < 0.001), poor tumor differentiation (p = 0.002), signet ring cell histology (p = 0.003), lymphovascular invasion (p < 0.001), and perineural invasion (p < 0.001). Multivariable logistic regression identified total gastrectomy (OR: 2.14), T4 tumor stage (OR: 2.93), N3 nodal status (OR: 2.87), and lymphovascular invasion (OR: 2.87) as independent predictors of postoperative mortality. Cox regression analysis revealed that combined tumor location (HR: 1.73), total gastrectomy (HR: 1.56), lymphovascular invasion (HR: 2.63), T4 tumor stage (HR: 1.93), N3 nodal status (HR: 1.71), and distant metastasis (HR: 1.74) were independently associated with decreased overall survival. Conclusions: Although gastric cancer surgery continued during the COVID-19 pandemic, some delays in pathology reporting were observed; however, these did not significantly affect the timing of adjuvant therapy or patient outcomes. Importantly, pandemic timing was not identified as an independent risk factor for mortality in multivariable logistic regression analysis, nor for survival in multivariable Cox regression analysis. Instead, tumor burden and aggressiveness-specifically advanced stage, lymphovascular invasion, and total gastrectomy-remained the primary independent determinants of poor prognosis. While pandemic-related workflow delays occurred, institutional adaptability preserved oncologic outcomes.
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    Impact of the COVID-19 Pandemic on Colorectal Cancer Surgery: Surgical Outcomes and Tumor Characteristics in a Multicenter Retrospective Cohort
    (Mdpi, 2025) Sahin, Emrah; Akbulut, Sami; Ogut, Zeki; Yilmaz, Serkan; Dalda, Yasin; Tuncer, Adem; Kucukakcali, Zeynep
    Background: Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide. The COVID-19 pandemic disrupted healthcare systems globally, raising concerns about delays in CRC diagnosis and treatment, and their potential negative effects on surgical outcomes. However, the extent of this impact remains uncertain. Aim: To compare the clinical characteristics, treatment strategies, and outcomes of CRC patients between the Pre-COVID-19 and COVID-19 Era groups, and to identify independent predictors of metastasis and mortality. Methods: This retrospective multicenter study included 397 CRC patients who underwent surgical treatment between 1 July 2018, and 1 August 2021, at three tertiary medical centers. Patients were divided into two groups: Pre-COVID-19 (n = 213) and COVID-19 Era (n = 184). Demographic data, tumor characteristics, surgical approach, postoperative complications, and survival outcomes were analyzed. Logistic regression analysis was conducted to identify independent predictors of metastasis and mortality. Results: The median age was 64 years (95% CI: 63-66), with 59.2% being male. Compared to the Pre-COVID-19 group, patients in the COVID-19 Era had significantly larger tumors (p < 0.001), with a significantly higher total LN retrieved (p = 0.006), more advanced T-stage (p = 0.007), higher N2 lymph node involvement (p = 0.027), and poorer tumor differentiation (p = 0.030). Intestinal perforation was more frequent in the Pre-COVID-19 group (p = 0.042). Multivariate analysis revealed increased odds of mortality associated with the positive LN retrieved (OR: 1.14; p = 0.001), moderate tumor differentiation (OR: 2.99; p = 0.043), poor differentiation (OR: 4.57; p = 0.023), undifferentiated histology (OR: 6.95; p = 0.028), intestinal obstruction (OR: 2.67; p = 0.007), intestinal perforation (OR: 11.76; p < 0.001), and distant metastasis (OR: 2.86; p = 0.008). Regarding metastasis, elevated preoperative CEA (OR: 1.02; p = 0.002), lymph node involvement (OR: 4.87; p = 0.002), and perineural invasion (OR: 2.17; p = 0.033) were independently associated with increased odds of metastasis. Conclusions: Although overall survival did not differ significantly between groups, patients treated during the COVID-19 Era exhibited more advanced histopathological characteristics, including a higher proportion of T4 tumors, increased N2 lymph node involvement, and poorer differentiation grades. Despite no significant differences in postoperative complications between groups, it is noteworthy that preoperative intestinal perforation was less frequent in the COVID-19 Era cohort.
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    Investigation of the effect of oral and internal bisphosphonate use on bone density in the jaws in patients with osteoporosis in panoramic radiography
    (Elsevier Science Inc, 2023) Musulluoglu, Ferhat; Alan, Hilal; Yilmaz, Serkan
    Objectives: This study aims to quantitatively evaluate the effects of bisphosphonate use duration and route of administration on mandibular cortical and trabecular bone in postmenopausal women. Study design: Ninety postmenopausal women over the age of 50 were included in this study. Trabecular bone density was specified numerically by fractal dimension (FD) in the region of interest selected on the panoramic radiograph. The width of the mandibular cortical (MCW) bone under the mental foramen of the mandible was measured. Mann-Whitney U test was used for parameters that did not show a normal distribution. Spearman rho correlation test was used to determine the relationship between continuous measurement parameters. Results: It was observed that FD and MCW of dentate and edentate individuals using bisphosphonate were statistically significantly lower than those of healthy individuals (P < .05). There was no significant correlation was found between the duration of use of bisphosphonates and the fractal values obtained from the relevant regions of the mandible (P > .05). Conclusion: Fractal dimension was found to be lower in oral bisphosphonate use than in intravenous bisphosphonate use. The width of the mandibular cortical bone values was found to be lower in individuals using bisphosphonate than in healthy individuals. Fractal dimension and MCW may benefit clinicians as quantitative parameters in panoramic radiography in the diagnosis of osteoporosis.