ONUR ALKAN

@suleymanyalcinsh.saglik.gov.tr

Department of Medical Oncology
Goztepe Prof. Dr. Suleyman Yalcin City Hospital

ONUR ALKAN


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RESEARCH, TEACHING, or OTHER INTERESTS

Oncology, Internal Medicine
7

Scopus Publications

Scopus Publications

  • Comment on “PARP-1 rs1136410 Polymorphism and Gastrointestinal Cancer Risk: A Meta-Analysis of Cancer-Type and Ethnic-Specific Associations”
    Onur ALKAN, Ismail NAZLI, Ahmet BASGOZE
    Medeniyet Medical Journal, 2026
  • Does Surgical Timing After Neoadjuvant Anti-HER2 Therapy Affect Pathological Complete Response and Survival in HER2-Positive Breast Cancer? A Multicenter Retrospective Cohort Study
    Zeliha Birsin, Onur Alkan, Hülya Odabaşı Bükün, İsmail Nazlı, Murat Günaltılı, Emir Çerme, Vali Aliyev, Selin Cebeci, Seda Jeral, Hamza Abbasov, Ebru Çiçek, Türkkan Evrensel, Çiğdem Papila, Berrin Papila, Ceyda Sönmez Wetherilt, Nebi Serkan Demirci, Özkan Alan
    Journal of Surgical Oncology, 2026
    Background The optimal timing of surgery after completion of neoadjuvant chemotherapy (NAC) remains uncertain, particularly for patients with HER2‐positive breast cancer receiving targeted therapy. Methods This multicenter retrospective study included 176 patients with early or locally advanced HER2‐positive breast cancer who underwent surgery following neoadjuvant chemotherapy combined with anti‐HER2 therapy between 2010 and 2025. The study was conducted using a previously established multicenter real‐world cohort (Birsin et al. 2025). This dataset has been used in prior analyses focusing on different endpoints; however, the current study addresses a distinct research question evaluating the impact of surgical timing after neoadjuvant therapy. Patients were categorized according to the interval between the last cycle of systemic therapy and surgery into three groups: < 4 weeks, 4–8 weeks, or > 8 weeks. The primary endpoint was pathological complete response (pCR), defined as ypT0/is ypN0. Secondary endpoints were disease‐free survival (DFS) and overall survival (OS). Results The median interval between completion of NAC and surgery was 8 weeks (range, 3–20 weeks). A pCR was achieved in 49% of patients. In multivariate analysis, hormone receptor negativity (OR = 2.56, p = 0.011), HER2 IHC 3+ status (OR = 0.27, p = 0.018), lower T stage (OR = 0.39, p = 0.026), and dual anti‐HER2 therapy (OR = 2.47, p = 0.021) were independent predictors of pCR; however, surgical timing (< 8 weeks vs. ≥ 8 weeks; < 4 vs. 4–8 weeks; and < 4 vs. > 8 weeks) did not significantly influence pCR ( p = 0.893, p = 0.171, p = 0.187). The estimated 5‐year DFS rates were 87.5%, 83.5%, and 80.8%, and the OS rates were 85.2%, 82.1%, and 89.7% for the < 4‐week, 4–8‐week, and > 8‐week groups, respectively. Neither DFS nor OS differed significantly among the groups (log‐rank p = 0.828 and p = 0.778, respectively). Conclusions In patients with early and locally advanced HER2‐positive breast cancer, the interval between completion of neoadjuvant chemotherapy combined with anti‐HER2 therapy and surgery did not affect pCR, DFS, or OS. Moderate delays in surgery beyond 8 weeks did not appear to adversely affect patient outcomes.
  • KELIM PSA as a Prognostic Biomarker in Castration-Resistant Prostate Cancer Treated with ARPI
    Fatih Atalah, Fatih Kuş, Aydın Acarbay, Akgün Karakök, Onur Alkan, İsmail Nazlı, Utku Özilice, Mehmet Beşiroğlu, Mahmut Gümüş
    Journal of Clinical Medicine, 2025
    Background/Objectives: Prostate cancer is a leading cause of cancer-related morbidity and mortality. While prostate-specific antigen (PSA) is crucial for monitoring, its static levels are limited in predicting outcomes precisely. The Kinetics of Elimination of PSA (KELIM PSA) has recently emerged as a dynamic biomarker of treatment response. This research sought to determine the predictive power of KELIM PSA in castration-resistant prostate cancer (CRPC) on androgen receptor pathway inhibitors (ARPI). Methods: This study retrospectively analyzed 98 CRPC patients treated with enzalutamide or abiraterone. The patients were categorized as either unfavorable (KELIM < 1) or favorable (KELIM ≥ 1). Demographic and clinical characteristics were compared, and survival outcomes were evaluated using Kaplan–Meier curves and Cox regression. Results: Of the cohort, 42 (42.9%) patients had favorable and 56 (57.1%) unfavorable KELIM values. The unfavorable group had a higher mortality rate (62.5% vs. 38.1%, p = 0.029). Univariate analysis showed that poor KELIM results increased mortality risk twofold (hazard ratio [HR]: 2.30, 95% confidence interval [CI]: 1.26–4.19, p = 0.006). In multivariable analysis, unfavorable KELIM remained independently associated with worse overall survival (HR: 2.09, 95% CI: 1.12–3.89, p = 0.020), together with second-line ARPI (HR: 3.19, 95% CI: 1.71–5.93, p < 0.001) and ADT + docetaxel during CSPC (HR: 2.14, 95% CI: 1.11–4.12, p = 0.022). Kaplan–Meier curves revealed that the unfavorable group had notably reduced overall survival and progression-free survival (log-rank p = 0.018). Conclusions: KELIM PSA is an independent predictor in ARPI-treated CRPC. By integrating PSA kinetics into prognostic models, risk stratification may be improved, and this may guide individualized treatment. Prospective multicenter validation is warranted.
  • Inflammatory and Nutritional Markers Predicting Pathological Complete Response to Neoadjuvant Therapy in HER2-Positive Breast Cancer: A Multicenter Real-World Study
    Zeliha Birsin, İsmail Nazlı, Onur Alkan, Hülya Odabaşı Bükün, Murat Günaltılı, Emir Çerme, Vali Aliyev, Selin Cebeci, Seda Jeral, Hamza Abbasov, Türkkan Evrensel, Çiğdem Papila, Berrin Papila, Ceyda Sönmez Wetherilt, Nebi Serkan Demirci, Özkan Alan
    Journal of Clinical Medicine, 2025
    Background: Pathological complete response (pCR) following neoadjuvant therapy (NAT) is a key surrogate marker for long-term outcomes in HER2-positive breast cancer. Identifying clinical and biological predictors of pCR, including systemic inflammatory and nutritional markers such as the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), neutrophil-to-albumin ratio (NAR), C-reactive protein-to-albumin ratio (CAR), systemic immune-inflammation index (SII), and prognostic nutritional index (PNI), may help refine treatment strategies and improve patient outcomes. Methods: We retrospectively analyzed 174 patients with stage II–III HER2-positive breast cancer who received neoadjuvant anti-HER2-based regimens at multiple centers between 2010 and 2025. Demographic, clinicopathological, and laboratory data were collected, and inflammatory and nutritional indices (NLR, PLR, LMR, NAR, CAR, SII, PNI) were calculated. Predictors of pCR were evaluated using univariate and multivariate logistic regression analyses. Results: Overall, 49% of patients achieved pCR. In multivariate analysis, independent predictors of pCR were hormone receptor negativity, smaller tumor size, HER2 IHC 3+ expression, dual HER2 blockade, and a higher prognostic nutritional index (PNI ≥ 55). In contrast, systemic inflammatory indices such as NLR, PLR, LMR, NAR, CAR, and SII were not significantly associated with pCR. Conclusions: This multicenter real-world study demonstrates that conventional inflammatory markers have limited predictive value, whereas the PNI emerges as a simple and practical biomarker reflecting nutritional and immune status. Integrating PNI with clinicopathological factors may enhance risk stratification and help guide individualized neoadjuvant treatment strategies in HER2-positive breast cancer.
  • Criteria for Hyperinflammation Developing in COVID-19: Analysis of 2 Cohorts From Different Periods of the Pandemic
    Shirkhan Amikishiyev, M. Guven Gunver, Murat Bektas, Sarvan Aghamuradov, Burak Ince, Nevzat Koca, Ege Sinan Torun, Numune Aliyeva, Selma Sari, Cigdem Cetin, Banu C. Yalcin‐Dulundu, Rabia Deniz, Fatih Kemik, Besim Fazil Agargun, Ubeyde Ayse Gulseren, Beliz Besisik, Onur Alkan, Ceren Bagriacik, Yavuz B. Tor, Naci Senkal, Yunus Catma, Gorkem Durak, Sevim Mese, Ali Agacfidan, Murat Kose, Mustafa Erelel, A. Atahan Cagatay, Serap Simsek‐Yavuz, Sevgi Kalayoglu‐Besisik, Figen Esen, Ahmet Gül
    Arthritis and Rheumatology, 2023
    ObjectiveHyperinflammation (HI) that develops in week 2 of COVID‐19 contributes to a worse outcome. Because week 2 laboratory findings can be relatively mild, the available criteria for classification of hemophagocytic lymphohistiocytosis or macrophage activation syndrome are not helpful.MethodsOur study included a discovery cohort of patients from Turkey with symptomatic COVID‐19 who were followed up while hospitalized during the initial wave and a replication cohort of hospitalized patients from a later period, all of whom required oxygen support and received glucocorticoids. Diagnosis of HI was made by an expert panel; most patients with COVID‐19–associated HI (HIC) received tocilizumab or anakinra. Clinical and laboratory data from start day of treatment with tocilizumab or anakinra in HIC patients were compared with the data from day 5–6 in patients without HIC. Values maximizing the sensitivity and specificity of each parameter were calculated to determine criteria items.ResultsThe discovery cohort included 685 patients, and the replication cohort included 156 patients, with 150 and 61 patients receiving treatment for HI, respectively. Mortality rate in HI patients in the discovery cohort (23.3%) was higher than the rate in patients without HI (3.7%) and the rate in patients in the overall replication cohort (10.3%). The 12‐item criteria that we developed for HIC showed that a score of 35 provided 85.3% sensitivity and 81.7% specificity for identification of HIC. In the replication cohort, the same criteria resulted in 90.0% sensitivity for HIC; however, lower specificity values were observed because of the inclusion of milder cases of HIC responding only to glucocorticoids.ConclusionThe use of the 12‐item criteria for HIC can better define patients with HIC with reasonable sensitivity and specificity and enables an earlier treatment start.image
  • High levels of circulating il-6 and il-8 signature can predict covid-19 severity
    Didem Ozgür, Murat Karamese, Alpay Medetalibeyoglu, Onur Alkan, Naci Senkal, Emin Ediz Tutuncu
    Jundishapur Journal of Microbiology, 2021
    Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may trigger a cytokine storm, which is characterized by uncontrolled overproduction of proinflammatory cytokines. Objectives: We aimed to investigate the association between circulating levels of inflammatory cytokines and severity of coronavirus disease 2019 (COVID-19). Methods: This cross-sectional study included 46 severe and 32 mildly symptomatic COVID-19 patients. The serum levels of cytokines and chemokines were determined using the Bio-Plex ProTM Human Cytokine Screening Panel. Results: Out of a total of 78 patients with confirmed COVID-19, 54 (69.2%) were males, and 24 (30.8%) were females. The mean age was 43.1 ± 13.3 and 58.2 ± 15 in mild and severe patients, respectively. Severe patients were characterized by significant laboratory abnormalities, such as increased WBC (P = 0.002) and neutrophil counts (P = 0.001), higher levels of ALT (P = 0.03), AST (P = 0.002), LDH (P < 0.001), urea (P = 0.013), ferritin (P < 0.001), D-dimer (P = 0.042), CRP (P < 0.001), and decreased lymphocyte (P < 0.001) and platelet (P = 0.045) counts. The levels of IL-6, IL-8, IL-13, TNF-α, IFN-γ, MIP-1β, and MCP-1 increased in the severe group compared to the mild group. However, significant differences were observed only for IL-6 (P < 0.001) and IL-8 (P < 0.001) levels. Conclusions: Serum IL-6 and IL-8 levels can be used as potential prognostic biomarkers of disease severity in COVID-19 patients.
  • Myelomatous Pleural Effusion: A Rare Involvement in Myeloma
    Onur Alkan, Tarik Onur Tiryaki, Sevgi Kalayoglu-Besisik
    Journal of Medical Cases, 2020
    Extramedullary disease (EMD) incidence is between 7% and 18% in multiple myeloma. Overall survival of patients who develop EMD is significantly shorter than that of patients without EMD. Malignant myelomatous pleural effusions (MPEs) are rarely observed, occurring in less than 1% of cases. The diagnosis of MPE was confirmed by the detection of myeloma cells in the pleural fluid using flow cytometric analyses. We present a case of a 67-year-old male patient with IgG-kappa myelom. After a few line treatment regimens, he was admitted to hospital with back pain and blurred consciousness, and pleural effusion was detected. Pleural fluid analysis showed malignant plasma cells. It is a rare presentation of multiple myeloma, but important in diagnosis.